Post by: Whatlol on November 11, 2010, 11:10:34 am
How did you guys find it?
Post by: sajib_mostofa on November 11, 2010, 11:12:07 am
Post by: Sheen on November 11, 2010, 11:12:29 am
btw why isn't there a Chemistry board?
Post by: Whatlol on November 11, 2010, 11:13:22 am
it was pretty easy i'd say...
btw why isn't there a Chemistry board?
i was asking myself that too... )= dunno hopefully there will be one up soon?
long
there were a few questions but i didnt really think it took long to do them??
Post by: becca92 on November 11, 2010, 11:14:12 am
Post by: Whatlol on November 11, 2010, 11:14:47 am
Too easy for my liking, now the cutoff will be extremely high :(
yea thats what i was thinking
Post by: _henwee on November 11, 2010, 11:19:22 am
Why was oxygen pumped at a high pressure?
I totally guessed that. >.<"
Post by: Whatlol on November 11, 2010, 11:19:48 am
Some explaining questions were blah...
Why was oxygen pumped at a high pressure?
I totally guessed that. >.<"
yea id rather not share what i wrote because its laughable
Post by: jayna on November 11, 2010, 11:20:31 am
longI thought it finished at 10.30 caused me to rush like a mofo. Skipped the one mark q's. THen when it was 10.30 im like "Why is examiner giving us advantage??" *FACEPALM* iTS 10.45 retard :uglystupid2:
Went back filled in all the answers in. :) And corrected incorrect ans :D
Exam was unfortunately easy. If i studied i would of got a v. high mark.
Post by: Studyinghard on November 11, 2010, 11:20:41 am
Post by: Studyinghard on November 11, 2010, 11:21:58 am
Post by: jayna on November 11, 2010, 11:22:23 am
I wrote for that oxygen question that the solid nature of the benzoic acid need a high pressure for the reaction to occur quickly otherwise it would be too slow. yeh i know, wtf right?I wrote so reaction rate is increased...or sum shit
Post by: curious111 on November 11, 2010, 11:22:48 am
WHAT THE HELL WAS 16? did people get C or D? the reduction equation questiosn
I got C for that.
Post by: jayna on November 11, 2010, 11:23:38 am
SAMEWHAT THE HELL WAS 16? did people get C or D? the reduction equation questiosn
I got C for that.
Post by: meefz on November 11, 2010, 11:23:49 am
WHAT THE HELL WAS 16? did people get C or D? the reduction equation questiosn
I got C for that.
Same here.
Post by: Studyinghard on November 11, 2010, 11:25:14 am
Post by: samiira on November 11, 2010, 11:25:36 am
Some explaining questions were blah...
i wrote the biggest bullcrap for many of the questions.. i didnt like the exam.. thought it was weird.. mayb coz the stuff i concentrated on wasnt really there.. :/
Post by: brandonio on November 11, 2010, 11:26:01 am
Post by: Studyinghard on November 11, 2010, 11:26:51 am
4) A
5) B
Post by: sajib_mostofa on November 11, 2010, 11:27:11 am
Post by: Dawson on November 11, 2010, 11:27:55 am
Post by: samiira on November 11, 2010, 11:28:19 am
was q3 MC - D -it affects none of them
4) A
5) B
das wat i got for q3 aswell
Post by: Xavier1234 on November 11, 2010, 11:28:25 am
was q3 MC - D -it affects none of them
4) A
5) B
yeah thats what i put in. this is the graph question where volume was decreased yeah?
Post by: Xavier1234 on November 11, 2010, 11:29:17 am
Post by: sajib_mostofa on November 11, 2010, 11:29:36 am
Post by: Xavier1234 on November 11, 2010, 11:30:05 am
Was Q3 MCQ the effect of the volume change on concentration or the rate?
yep.
Post by: Studyinghard on November 11, 2010, 11:30:14 am
was q3 MC - D -it affects none of them
4) A
5) B
yeah thats what i put in. this is the graph question where volume was decreased yeah?
yes, that was the question.
What about the concentration fraction question. Did anyone get D it was where the fraction was 1/3
Post by: Studyinghard on November 11, 2010, 11:30:53 am
Was Q3 MCQ the effect of the volume change on concentration or the rate?
No, 3 was effect of volume change on enthalpy values and such.
Post by: curious111 on November 11, 2010, 11:31:32 am
was q3 MC - D -it affects none of them
4) A
5) B
yeah thats what i put in. this is the graph question where volume was decreased yeah?
yes, that was the question.
What about the concentration fraction question. Did anyone get D it was where the fraction was 1/3
Yeah that question was D because the ratio was 3:1, the others were either 1:1 or 2:1
Post by: sajib_mostofa on November 11, 2010, 11:33:38 am
Post by: curious111 on November 11, 2010, 11:34:37 am
For Q4, what did the poisoning of the catalyst do to the rate of reaction?
I put C for that (that the rate stayed constant). Not sure though. :S
EDIT: Argh this is wrong. Stupid mistake :(
Post by: 10weid on November 11, 2010, 11:35:18 am
Post by: andy456 on November 11, 2010, 11:35:49 am
For Q4, what did the poisoning of the catalyst do to the rate of reaction?A
it essentially removed the catalyst so the rate would drop but then remain constant
Post by: samiira on November 11, 2010, 11:36:10 am
can sum1 please make a chem thread?yeh i reckon
Post by: Xavier1234 on November 11, 2010, 11:37:00 am
For Q4, what did the poisoning of the catalyst do to the rate of reaction?
I put C for that (that the rate stayed constant). Not sure though. :S
isnt it like saying K is not affected by catalysts hence C concentration is constant? thats what i put in.
Post by: Studyinghard on November 11, 2010, 11:38:02 am
For Q4, what did the poisoning of the catalyst do to the rate of reaction?
I put C for that (that the rate stayed constant). Not sure though. :S
isnt it like saying K is not affected by catalysts hence C concentration is constant? thats what i put in.
Rate question is question 4, Q 5 is the concentration question. However we are not arguing for this whether the K has changed we are going the speed of the concentration change which is why I got 4) A and 5)B
Post by: Whatlol on November 11, 2010, 11:38:22 am
Post by: Xavier1234 on November 11, 2010, 11:39:45 am
I said 4 a and 5 c )=
same lol. hooray for chem as 10%
Post by: Studyinghard on November 11, 2010, 11:41:09 am
I said 4 a and 5 c )=
same lol. hooray for chem as 10%
oh crap, i see how 5 is C now because I thought B because I felt it was asking the concentration after the catalyst was added was it not?
Post by: andy456 on November 11, 2010, 11:41:45 am
I think 5 is C because catalysts only effect the rate of reaction... nothing else... so it says the system is already at equlibrium so if you remove the catalyst only the rate will change meaning concentration will remain constant. therefore 5 C
Post by: Whatlol on November 11, 2010, 11:41:58 am
I said 4 a and 5 c )=
same lol. hooray for chem as 10%
oh crap, i see how 5 is C now because I thought B because I felt it was asking the concentration after the catalyst was added was it not?
it was at equilibrium, so the equilibrium positions shouldnt be affected by the poisoning of the catalyst
Post by: sajib_mostofa on November 11, 2010, 11:42:46 am
I said 4 a and 5 c )=
same lol. hooray for chem as 10%
oh crap, i see how 5 is C now because I thought B because I felt it was asking the concentration after the catalyst was added was it not?
Catalyst doesnt have any effect on concentration. It only affects that rate of reaction.
Post by: jayna on November 11, 2010, 11:43:32 am
Post by: samiira on November 11, 2010, 11:43:42 am
thats what i thought aswellI said 4 a and 5 c )=
same lol. hooray for chem as 10%
oh crap, i see how 5 is C now because I thought B because I felt it was asking the concentration after the catalyst was added was it not?
Catalyst doesnt have any effect on concentration. It only affects that rate of reaction.
Post by: Studyinghard on November 11, 2010, 11:44:19 am
What did people get for 7 and 8
Post by: Xavier1234 on November 11, 2010, 11:44:38 am
Post by: andy456 on November 11, 2010, 11:45:15 am
touche, i see it. its C7 D, 8 A
What did people get for 7 and 8
EDIT: put in wrong letters.... duuuuuuuuuuuuuhhhhh
Post by: sajib_mostofa on November 11, 2010, 11:46:02 am
Post by: mostafa1002 on November 11, 2010, 11:46:16 am
Post by: Studyinghard on November 11, 2010, 11:46:27 am
touche, i see it. its C7 A, 8 B
What did people get for 7 and 8
I got 7) D =/
Post by: Studyinghard on November 11, 2010, 11:46:43 am
How bout Q 11?
11 is B, almost sure of this.
Post by: curious111 on November 11, 2010, 11:47:12 am
How bout Q 11?
It was B (More reactant molecules than Product) because product yield increased with increasing pressure
Post by: andy456 on November 11, 2010, 11:47:38 am
Sorry i made a mistake.... edited my original posttouche, i see it. its C7 A, 8 B
What did people get for 7 and 8
I got 7) D =/
7 d 8 a
Post by: Studyinghard on November 11, 2010, 11:47:56 am
Post by: sajib_mostofa on November 11, 2010, 11:48:01 am
Post by: sajib_mostofa on November 11, 2010, 11:48:29 am
What did people get for 19? Did we get A?
Yeah
Post by: Whatlol on November 11, 2010, 11:48:59 am
How can you tell that there wasn't the same amount of mole on each side?
cause yeild increases with pressure, therefore higher particle concentration in reactants
Post by: _henwee on November 11, 2010, 11:49:06 am
Sorry i made a mistake.... edited my original posttouche, i see it. its C
What did people get for 7 and 8
7 A, 8 B
I got 7) D =/
7 d 8 a
You scared the crap out of me.
Post by: mostafa1002 on November 11, 2010, 11:49:34 am
Post by: Linkage1992 on November 11, 2010, 11:49:39 am
Post by: kristian92 on November 11, 2010, 11:50:03 am
Post by: Studyinghard on November 11, 2010, 11:50:21 am
Sorry i made a mistake.... edited my original posttouche, i see it. its C
What did people get for 7 and 8
7 A, 8 B
I got 7) D =/
7 d 8 a
You scared the crap out of me.
dw me too haha
Okay all the ambiguous MC out of the way. What did people get for 3)ii
What happens if ammonia is low or high? i was just like wtf?
Post by: mirra250 on November 11, 2010, 11:50:43 am
What did people get for 19? Did we get A?I did D.. only because it was the last answer I cancelled out. I swear they are all wrong!!
Post by: andy456 on November 11, 2010, 11:51:02 am
i got 19 C reactants are not stored in a fuel cell....I concur.... this one tripped me up because before the exam i read the fuel cells need reactants to be continuously pumped into the system
Post by: mirra250 on November 11, 2010, 11:51:39 am
i know wtf! i just did that if it's too low a greater proportion of CO will be released, and if too high a greater proportion of NH3 will be releasedSorry i made a mistake.... edited my original posttouche, i see it. its C
What did people get for 7 and 8
7 A, 8 B
I got 7) D =/
7 d 8 a
You scared the crap out of me.
dw me too haha
Okay all the ambiguous MC out of the way. What did people get for 3)ii
What happens if ammonia is low or high? i was just like wtf?
Post by: Xavier1234 on November 11, 2010, 11:51:57 am
Post by: andy456 on November 11, 2010, 11:52:28 am
Same that question was shit....i know wtf! i just did that if it's too low a greater proportion of CO will be released, and if too high a greater proportion of NH3 will be releasedSorry i made a mistake.... edited my original posttouche, i see it. its C
What did people get for 7 and 8
7 A, 8 B
I got 7) D =/
7 d 8 a
You scared the crap out of me.
dw me too haha
Okay all the ambiguous MC out of the way. What did people get for 3)ii
What happens if ammonia is low or high? i was just like wtf?
Post by: _henwee on November 11, 2010, 11:52:41 am
i got 19 C reactants are not stored in a fuel cell....I concur.... this one tripped me up because before the exam i read the fuel cells need reactants to be continuously pumped into the system
Yayyer. =]
I thought so when I read that.
Post by: happycat on November 11, 2010, 11:52:55 am
Post by: Blackrat on November 11, 2010, 11:53:07 am
I said 4 a and 5 c )=
I got that.
For Q7 i said C, cause it had the most particles
and for Q8 i said A
Q 11, B
but... oh god I hope I'm right :-\
and Q3 I said D, but i guessed that one
Post by: mirra250 on November 11, 2010, 11:53:17 am
i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
Post by: Studyinghard on November 11, 2010, 11:53:20 am
Post by: Whatlol on November 11, 2010, 11:53:57 am
Post by: sajib_mostofa on November 11, 2010, 11:54:17 am
i know wtf! i just did that if it's too low a greater proportion of CO will be released, and if too high a greater proportion of NH3 will be releasedSorry i made a mistake.... edited my original posttouche, i see it. its C
What did people get for 7 and 8
7 A, 8 B
I got 7) D =/
7 d 8 a
You scared the crap out of me.
dw me too haha
Okay all the ambiguous MC out of the way. What did people get for 3)ii
What happens if ammonia is low or high? i was just like wtf?
You have more nitrogen oxide released then you have nitrogen and water if ammonia is low. The reverse happens when ammonia is high.
Post by: mostafa1002 on November 11, 2010, 11:54:31 am
pretty sure 19 was A.
reactants are not stored in a fuel cell....they have to be continuously supplied...
Post by: happycat on November 11, 2010, 11:54:41 am
pretty sure 19 was A.I think so to
Post by: Xavier1234 on November 11, 2010, 11:55:10 am
I thought it was easy. Did the M/C section quicker than I expected. I got stumped on a few of those S/A question though
same boat. what did people get for the correct E naught crap
Post by: mostafa1002 on November 11, 2010, 11:55:16 am
i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
NO...they go form the reductant to the anode...then then go to the cathode from the anode...
Post by: happycat on November 11, 2010, 11:55:51 am
Some explaining questions were blah...I said something like to get the reaction going, don't know if that's correct though
Why was oxygen pumped at a high pressure?
I totally guessed that. >.<"
Post by: curious111 on November 11, 2010, 11:55:57 am
I thought it was easy. Did the M/C section quicker than I expected. I got stumped on a few of those S/A question though
same boat. what did people get for the correct E naught crap
The only one that could be determined i thought was that the silver half cell was +0.22V
Post by: petethehorse on November 11, 2010, 11:57:05 am
Post by: andy456 on November 11, 2010, 11:57:25 am
I thought it was easy. Did the M/C section quicker than I expected. I got stumped on a few of those S/A question though
same boat. what did people get for the correct E naught crap
The only one that could be determined i thought was that the silver half cell was +0.22V
Booooo yeah, thats what i got too....
Post by: mirra250 on November 11, 2010, 11:58:25 am
oh wow! i see what you mean... that is SO ambiguous though! If they meant that they would/should have put "and then to the cathode" after.i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
NO...they go form the reductant to the anode...then then go to the cathode from the anode...
I believe they will accept all answers - it is way too ambiguous
Post by: Studyinghard on November 11, 2010, 11:58:47 am
i thought it was pretty good. but everyone is saying they got C for 16 (on like the first page of this) but i thought it was D becasue the charges looked to be balanced? anyone?
i was in the same boat, had no clue between C and D. then wrote C on one side of my rubber and D on another, ( this has worked for me before ) , and it landed on C and apparentally its the right answer :D
Post by: curious111 on November 11, 2010, 11:58:56 am
i thought it was pretty good. but everyone is saying they got C for 16 (on like the first page of this) but i thought it was D becasue the charges looked to be balanced? anyone?
The charges were balanced in answer C
Post by: mirra250 on November 11, 2010, 11:59:06 am
i thought it was pretty good. but everyone is saying they got C for 16 (on like the first page of this) but i thought it was D becasue the charges looked to be balanced? anyone?yes charges were balanced, but the Oxygen atoms were not. So C was the answer
Post by: Xavier1234 on November 11, 2010, 11:59:12 am
I thought it was easy. Did the M/C section quicker than I expected. I got stumped on a few of those S/A question though
same boat. what did people get for the correct E naught crap
The only one that could be determined i thought was that the silver half cell was +0.22V
really? fml i did Cd+. 2 marks down the drain lol. i cant care less about the exam right now
Post by: happycat on November 11, 2010, 11:59:20 am
I thought that one where you had the student doing online research and making predictions was wtf I was stumped at the one. And damn I didn't have enough time for that write the coefficients in the ammonia or whatever it was question.Some explaining questions were blah...
i wrote the biggest bullcrap for many of the questions.. i didnt like the exam.. thought it was weird.. mayb coz the stuff i concentrated on wasnt really there.. :/
Post by: happycat on November 11, 2010, 12:00:12 pm
was q3 MC - D -it affects none of themYay goodee I got that one :)
4) A
5) B
Post by: Studyinghard on November 11, 2010, 12:00:31 pm
Post by: sajib_mostofa on November 11, 2010, 12:01:04 pm
WHICH ONE IS MORE SUSTAINABLE? Natural gas or biochemical fuel crap? i said biochemical fuel
Same. Is it renewable?
Post by: Whatlol on November 11, 2010, 12:01:20 pm
WHICH ONE IS MORE SUSTAINABLE? Natural gas or biochemical fuel crap? i said biochemical fuel
yea i said the biomass, because it can be renewed within a suitible time frame.
Post by: Studyinghard on November 11, 2010, 12:01:32 pm
I thought that one where you had the student doing online research and making predictions was wtf I was stumped at the one. And damn I didn't have enough time for that write the coefficients in the ammonia or whatever it was question.Some explaining questions were blah...
i wrote the biggest bullcrap for many of the questions.. i didnt like the exam.. thought it was weird.. mayb coz the stuff i concentrated on wasnt really there.. :/
i found that easy, the two reasons were because the concentration wasnt 1 M and 25 degrees ( which is what you need for electrochemical series) It wasnt 1M because he used a liquid electrolyte therefore high concentration and 190 degrees
Post by: Xavier1234 on November 11, 2010, 12:01:39 pm
WHICH ONE IS MORE SUSTAINABLE? Natural gas or biochemical fuel crap? i said biochemical fuel
yeah. biochem coz natural gas is non-renewable. whilst biochem can be from your crap, my crap, cow crap, whoevers crap
Post by: jayna on November 11, 2010, 12:01:46 pm
HOW? Aren't the reactants for a fuel cell fed into the cell. Ie (O2 is pumped into the fuel cell?) Its not stored in the cell...pretty sure 19 was A.I think so to
BTW i put c for q 19
Post by: Duck on November 11, 2010, 12:01:55 pm
Post by: lisafaustina on November 11, 2010, 12:02:30 pm
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Post by: happycat on November 11, 2010, 12:02:33 pm
Rate woul've changed as a result of the catalyst being poisoned so your wrong dude sorryFor Q4, what did the poisoning of the catalyst do to the rate of reaction?
I put C for that (that the rate stayed constant). Not sure though. :S
EDIT: Argh this is wrong. Stupid mistake :(
Post by: crayolé on November 11, 2010, 12:03:12 pm
Post by: Studyinghard on November 11, 2010, 12:03:21 pm
Post by: lisafaustina on November 11, 2010, 12:04:03 pm
Post by: curious111 on November 11, 2010, 12:04:20 pm
isnt 18) B ?? ??
Yeah it is, the water would stil react. The additional equation was just a red herring
Post by: siddajay92 on November 11, 2010, 12:04:33 pm
WHAT THE HELL WAS 16? did people get C or D? the reduction equation questiosn
I got C for that.
Same here.
I'm pretty sure it is D..
Post by: jayna on November 11, 2010, 12:04:37 pm
for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.Doesnt stored imply it remains inside the fuel cell for some time?
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Post by: Xavier1234 on November 11, 2010, 12:04:55 pm
Rate woul've changed as a result of the catalyst being poisoned so your wrong dude sorryFor Q4, what did the poisoning of the catalyst do to the rate of reaction?
I put C for that (that the rate stayed constant). Not sure though. :S
EDIT: Argh this is wrong. Stupid mistake :(
the question referred to concentration not rate :)
Post by: mirra250 on November 11, 2010, 12:05:48 pm
for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Post by: happycat on November 11, 2010, 12:06:19 pm
Silly question, but what was the exam out of? I forgot to look >.<I think it was out of 82 or something like that don't remember now to much daydreaming
Post by: curious111 on November 11, 2010, 12:06:33 pm
WHAT THE HELL WAS 16? did people get C or D? the reduction equation questiosn
I got C for that.
Same here.
I'm pretty sure it is D..
Answer D has two Oxygens on the reactant side, and three on the product side
Post by: Studyinghard on November 11, 2010, 12:06:38 pm
for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
I agree, for a second i thought THIS was the mistake on the exam everyone was talking about, but the actual mistake (electrons not having their charge) didnt even make a difference.
Post by: jayna on November 11, 2010, 12:07:31 pm
THis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Post by: Studyinghard on November 11, 2010, 12:08:30 pm
THis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
Post by: jake on November 11, 2010, 12:09:01 pm
Post by: jayna on November 11, 2010, 12:09:50 pm
Oxidation occurs at the anode. The chemical undergoing oxidation isnt the anode, the electrode that extracts the electrons is the anode.THis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
SAme thought process as jake ^. :)
Post by: andy456 on November 11, 2010, 12:10:05 pm
Electrons go from the reductant... (the chemical) to the anodeTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
after which they move to the cathode.... thatll be a hard question that very few get right i think
Post by: Studyinghard on November 11, 2010, 12:10:33 pm
Post by: Xavier1234 on November 11, 2010, 12:10:44 pm
THis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
Post by: siddajay92 on November 11, 2010, 12:11:11 pm
I thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
Post by: curious111 on November 11, 2010, 12:11:23 pm
Had to be pretty savvy to get that right without guessing
Post by: mirra250 on November 11, 2010, 12:11:28 pm
technically they do yes but it is way too ambiguous because they made it sound like the electrons end at the anode, whereas they end at the cathode. Im 99% sure they'll give a mark for all answers to this questionTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Post by: jayna on November 11, 2010, 12:11:48 pm
Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
Post by: happycat on November 11, 2010, 12:12:05 pm
WHICH ONE IS MORE SUSTAINABLE? Natural gas or biochemical fuel crap? i said biochemical fuelThat's what I wrote and also said why it was so because of it being considered carbon neutral since plants take in co2 through photosynthesis. Question wanted reason for it as well so 2 marks.
Post by: bomb on November 11, 2010, 12:12:20 pm
Post by: andy456 on November 11, 2010, 12:12:25 pm
yepI thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
Post by: ghadz7 on November 11, 2010, 12:12:56 pm
technically they do yes but it is way too ambiguous because they made it sound like the electrons end at the anode, whereas they end at the cathode. Im 99% sure they'll give a mark for all answers to this questionTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Pretty sure they will mark all answers wrong, they don't want anyone to get full marks :P
Post by: Xavier1234 on November 11, 2010, 12:13:06 pm
I thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
yeah decrease all.
Post by: Studyinghard on November 11, 2010, 12:13:11 pm
Post by: lisafaustina on November 11, 2010, 12:13:17 pm
Post by: sajib_mostofa on November 11, 2010, 12:13:34 pm
so with that poisoned catalyst question, the firrst graph had a dropped line than it goes horizontally forward... and the second one just remains constant yeh?
Correct
Post by: vexx on November 11, 2010, 12:14:08 pm
but yep, i'd say quite a fair paper - nothing too tricky really, some questions were quite stupid.
what did people put for the why the affect of changing ammonia (too high and too low) on the composition of products?
80/82 according to my chem teacheer :D
well done :)
Post by: Blakhitman on November 11, 2010, 12:14:50 pm
Did we all say that the CF would increase?
Yea, same amount used, less delta T so higher C.F
from c.f=E/delta T
Post by: Xavier1234 on November 11, 2010, 12:15:02 pm
Did we all say that the CF would increase?
is this the insulation? if it is, then yeah because the change in T is smaller as more heat is lost in environment
Post by: bomb on November 11, 2010, 12:15:29 pm
I thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
yeah decrease all.
Huh? my chem teacher said both concentrations would have to = 10^-14.....
So one goes up while the other goes down?
that was quite easy, i really need to see mao's solutions when he does it to see what stupids mistakes i may have made.
but yep, i'd say quite a fair paper - nothing too tricky really, some questions were quite stupid.
what did people put for the why the affect of changing ammonia (too high and too low) on the composition of products?80/82 according to my chem teacheer :D
well done :)
Thanks :) I studied SO hard.
Too high means toxic ammonia gets into the atmosphere, too low means NO gets into the atmosphere.
Post by: sajib_mostofa on November 11, 2010, 12:15:34 pm
I thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
yeah decrease all.
The concentration of H+ decreases but OH- increases doesnt it?
Post by: siddajay92 on November 11, 2010, 12:15:47 pm
Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
um the reductant is the anode.... so it's clearly not C
Post by: Studyinghard on November 11, 2010, 12:15:59 pm
Vex for that question i wrote if the ammonia is too low (becomes limiting) then some of the NO escapes into the atmosphere and if its too high then all NO is converted therefore no toxic fumes.
Im looking at minimum 76/82 :) max 78/82
Post by: jayna on November 11, 2010, 12:17:04 pm
Reductant isnt the anode. The anode is the rod.Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
um the reductant is the anode.... so it's clearly not C
Meh who cares anyway. CHems over its just one mark. Leet Mao figure it out.
Post by: happycat on November 11, 2010, 12:17:23 pm
I said decrease [H+] and increase [OH] seeing that initial conc. of H+ would've been higherI thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
so diluting would reduce conc. H+ but increase OH but probably wrong though
Post by: andy456 on November 11, 2010, 12:17:56 pm
The reductant is the ion that causes reduction while the anode is an electrode..Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
um the reductant is the anode.... so it's clearly not C
Post by: Xavier1234 on November 11, 2010, 12:18:02 pm
Bomb what did your teacher say for 19 MC
Vex for that question i wrote if the ammonia is too low (becomes limiting) then some of the NO escapes into the atmosphere and if its too high then all NO is converted therefore no toxic fumes.
Im looking at minimum 76/82 :) max 78/82
your reasoning on the stupid NH3 qstn sounds logical. you could be right
Post by: mirra250 on November 11, 2010, 12:18:20 pm
I thought the exam was fairly easy, except a few questions.agreed! OH- increases, H+ decreases
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
yeah decrease all.
The concentration of H+ decreases but OH- increases doesnt it?
Post by: _henwee on November 11, 2010, 12:19:07 pm
I said decrease [H+] and increase [OH] seeing that initial conc. of H+ would've been higherI thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
so diluting would reduce conc. H+ but increase OH
When I read that question first - Where the hell do OH ions come from?
Post by: Studyinghard on November 11, 2010, 12:19:22 pm
I thought the exam was fairly easy, except a few questions.agreed! OH- increases, H+ decreases
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
yeah decrease all.
The concentration of H+ decreases but OH- increases doesnt it?
I did the other way around, I did H+ increases and OH- decreases. I guess thats completely wrong :P
Post by: doter on November 11, 2010, 12:19:51 pm
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
Post by: 98.40_for_sure on November 11, 2010, 12:19:57 pm
1. D
2. C
3. D
4. A
5. C
6. A
7. D
8. A
9. B
10. D
11. B
12. C
13. C
14. B
15. D
16. C
17. B
18. B
19. C
20. D
Post by: slothpomba on November 11, 2010, 12:20:10 pm
so with that poisoned catalyst question, the firrst graph had a dropped line than it goes horizontally forward... and the second one just remains constant yeh?Correct
Like this.
(http://i51.tinypic.com/2jd4pz.png)
(http://i56.tinypic.com/34ngtv4.png)
Post by: Linkage1992 on November 11, 2010, 12:20:20 pm
Post by: sajib_mostofa on November 11, 2010, 12:20:42 pm
so with that poisoned catalyst question, the firrst graph had a dropped line than it goes horizontally forward... and the second one just remains constant yeh?Correct
Like this.
(http://i51.tinypic.com/2jd4pz.png)
(http://i56.tinypic.com/34ngtv4.png)
Yep
Post by: Studyinghard on November 11, 2010, 12:21:03 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
I dont think you will get the full marks probably 1/2 .
Post by: Xavier1234 on November 11, 2010, 12:21:29 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
Post by: happycat on November 11, 2010, 12:22:21 pm
OH would've come from the water that was used to dilute solutionI said decrease [H+] and increase [OH] seeing that initial conc. of H+ would've been higherI thought the exam was fairly easy, except a few questions.
How did you guys find it?
What about that multi about diluting HCL... decrease both [H+] and [OH] ?
so diluting would reduce conc. H+ but increase OH
When I read that question first - Where the hell do OH ions come from?
Post by: 98.40_for_sure on November 11, 2010, 12:22:33 pm
Post by: Studyinghard on November 11, 2010, 12:22:36 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
I dont think so because the data given was given for a reason to quote them. The temperature and concentration was higher.
Post by: Xavier1234 on November 11, 2010, 12:22:56 pm
so with that poisoned catalyst question, the firrst graph had a dropped line than it goes horizontally forward... and the second one just remains constant yeh?Correct
Like this.
(http://i51.tinypic.com/2jd4pz.png)
(http://i56.tinypic.com/34ngtv4.png)
thats the way :)
Post by: mirra250 on November 11, 2010, 12:23:30 pm
The reductant is the ion that causes reduction while the anode is an electrode..
[/quote]
NO not necessarily. What if the anode is reactive, IE Fe (s)? This is the reductant AND the anode. VCAA MADE A MISTAKE FOR THE 20TH TIME
Post by: Xavier1234 on November 11, 2010, 12:23:52 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
I dont think so because the data given was given for a reason to quote them. The temperature and concentration was higher.
lol sorry i dont remember the question on top of my head so could be the otherway round.
Post by: jayna on November 11, 2010, 12:23:58 pm
With dilution, the concentration of everything decreases. The pH may be higher, yes, but that is due to a lessened concentration of H+, not due to an increased concentration of OH-.I thought [OH-] is just like perceived anyway. DOesnt really exist. Given by formula (10^-14/[H3O+]) if Conc H30+ decreases. then OH- has to increase according to that formula... lol i dont really know, this is how i worked out the answer. probably wrong anyway.
Post by: Studyinghard on November 11, 2010, 12:24:27 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
I dont think so because the data given was given for a reason to quote them. The temperature and concentration was higher.
lol sorry i dont remember the question on top of my head so could be the otherway round.
exam is here ;)
http://vcenotes.com/forum/index.php/topic,32267.15.html
Post by: Blakhitman on November 11, 2010, 12:24:57 pm
CALL OF DUTYYYYYYYYYYYYYYYYYYYYYYYYYY TIME
Post by: happycat on November 11, 2010, 12:25:42 pm
Damn, I woul've lost marks to both of those M/C Q'sso with that poisoned catalyst question, the firrst graph had a dropped line than it goes horizontally forward... and the second one just remains constant yeh?Correct
Like this.
(http://i51.tinypic.com/2jd4pz.png)
(http://i56.tinypic.com/34ngtv4.png)
thats the way :)
Post by: Xavier1234 on November 11, 2010, 12:26:22 pm
arghhh why am I here!!!!!!
CALL OF DUTYYYYYYYYYYYYYYYYYYYYYYYYYY TIME
+1000000000000000000000000000000!! COD time. 50% of teenage pregnancy fell because of that. lol
Post by: happycat on November 11, 2010, 12:26:50 pm
arghhh why am I here!!!!!!lol, this has been my final exam for the year
CALL OF DUTYYYYYYYYYYYYYYYYYYYYYYYYYY TIME
Post by: kenhung123 on November 11, 2010, 12:27:01 pm
Its not concentration, the electrolyte was not a solution. Aqueous solution is a standard condition.Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
Post by: JenH12 on November 11, 2010, 12:27:26 pm
Most are probably wrong :(
1. D
2. C
3. D
4. A
5. C
6. A
7. D
8. A
9. B
10. D
11. B
12. C
13. C
14. B
15. D
16. C
17. B
18. B
19. C
20. D
I got the same except 18 and 19
Post by: doter on November 11, 2010, 12:28:27 pm
Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
I dont think so because the data given was given for a reason to quote them. The temperature and concentration was higher.
lol sorry i dont remember the question on top of my head so could be the otherway round.
Damn it, I looked at the page for ages, to find the change can't believe I missed it. :(
Post by: Studyinghard on November 11, 2010, 12:29:49 pm
Its not concentration, the electrolyte was not a solution. Aqueous solution is a standard condition.Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
but you can mention concentration because the concentration of a liquid electrolyte would be high.
Post by: jayna on November 11, 2010, 12:30:03 pm
NO not necessarily. What if the anode is reactive, IE Fe (s)? This is the reductant AND the anode. VCAA MADE A MISTAKE FOR THE 20TH TIME
The reductant is the ion that causes reduction while the anode is an electrode..
[/quote]
TRUE DAT. DARN VCAA. KILL EM ALL
Post by: andy456 on November 11, 2010, 12:31:21 pm
i said the liquid thingy could donate protons which may interfere with the reaction, wrong????Its not concentration, the electrolyte was not a solution. Aqueous solution is a standard condition.Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
but you can mention concentration because the concentration of a liquid electrolyte would be high.
Post by: vexx on November 11, 2010, 12:33:05 pm
Most are probably wrong :(
1. D
2. C
3. D
4. A
5. C
6. A
7. D
8. A
9. B
10. D
11. B
12. C
13. C
14. B
15. D
16. C
17. B
18. B
19. C
20. D
I got the same except 18 and 19
19 is A, i'd say you may have gotten 19/20
i said 8 is B, which people are tending to disagree with, so i guess we will wait and see what Mao thinks.
Post by: 3Xamz on November 11, 2010, 12:33:29 pm
Post by: Studyinghard on November 11, 2010, 12:33:52 pm
Most are probably wrong :(
1. D
2. C
3. D
4. A
5. C
6. A
7. D
8. A
9. B
10. D
11. B
12. C
13. C
14. B
15. D
16. C
17. B
18. B
19. C
20. D
I got the same except 18 and 19
19 is A, i'd say you may have gotten 19/20
i said 8 is C, which people are tending to disagree with, so i guess we will wait and see what Mao thinks.
I also said 8) C but again I fear its wrong :(
Post by: mustafa on November 11, 2010, 12:34:44 pm
For that dilution question the [H+] decreases and the [OH-] OBViOusly INCREASES.
There is à higher concentration of OH Ions in Water than in Acid. Hence à dilution will increase OH conc.
Pls correct me i am wrong
Post by: curious111 on November 11, 2010, 12:35:15 pm
EDIT: i think i meant 3.74% lol, memory is a bit hazy
Post by: Xavier1234 on November 11, 2010, 12:35:30 pm
Its not concentration, the electrolyte was not a solution. Aqueous solution is a standard condition.Hey guys for that last question part a, about the voltage not being the same
If I wrote that the temp is higher and the concentration was different, but then made up a new concentration and temp will I get any marks, I didn't notice that the temp change was to 1900 degrees.
since the voltage is lower, then the system was not in standard conditions. i.e. lower M, pressure, temp, etc. as long as the concentration and temp you made up is lower, then you can get marks for it
but you can mention concentration because the concentration of a liquid electrolyte would be high.
the actual V is lower than predicted V, so shouldnt it be less than standard conds?
Post by: jayna on November 11, 2010, 12:35:54 pm
Does anyone else remember getting 3.84% as the percentage ionisation for the lactic acid thing?Yeah .
Post by: vexx on November 11, 2010, 12:36:01 pm
if you dilute a solution, the concentration of H+ is going to decrease as the HCl increases in pH, and while that happens, the concentration of OH- increases.
Post by: drdr on November 11, 2010, 12:36:37 pm
Does anyone else remember getting 3.84% as the percentage ionisation for the lactic acid thing?
I got around that, i think 3.79% (i THINK), but it was probably dependent on whether we rounded or carried over our calculations from the previous step
Post by: vexx on November 11, 2010, 12:37:21 pm
Does anyone else remember getting 3.84% as the percentage ionisation for the lactic acid thing?
I got around that, i think 3.79% (i THINK), but it was probably dependent on whether we rounded or carried over our calculations from the previous step
yeah i also got around 3.79%
Post by: 3Xamz on November 11, 2010, 12:37:52 pm
ahh sorry, i meant to say i did B
if you dilute a solution, the concentration of H+ is going to decrease as the HCl increases in pH, and while that happens, the concentration of OH- increases.
Hence the pH would increase, since the concentration of H+ is now lower.
Gah, sorry Vexx misread your post.
Post by: Blakhitman on November 11, 2010, 12:38:15 pm
Post by: mirra250 on November 11, 2010, 12:38:45 pm
Ummmmm, guys seriosuly....so true!! Q8 = B
For that dilution question the [H+] decreases and the [OH-] OBViOusly INCREASES.
There is à higher concentration of OH Ions in Water than in Acid. Hence à dilution will increase OH conc.
Pls correct me i am wrong
Post by: 98.40_for_sure on November 11, 2010, 12:38:50 pm
Ummmmm, guys seriosuly....
For that dilution question the [H+] decreases and the [OH-] OBViOusly INCREASES.
There is à higher concentration of OH Ions in Water than in Acid. Hence à dilution will increase OH conc.
Pls correct me i am wrong
My reasoning is that the shift cannot fully compensate for the initial dilution?
but imo a bit ambiguous. "the effect" could also refer to the change AFTER dilution or OF dilution. shit ass vcaa -_-
Post by: Shark 774 on November 11, 2010, 12:39:48 pm
i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
Post by: Studyinghard on November 11, 2010, 12:40:19 pm
I dont think the calculation questions were that much of a problem.
Xavier I'm pretty sure it wasnt lower than SC because the temperature used was 190 degrees ( 165 above SC)
Post by: Shark 774 on November 11, 2010, 12:40:41 pm
Ummmmm, guys seriosuly....
For that dilution question the [H+] decreases and the [OH-] OBViOusly INCREASES.
There is à higher concentration of OH Ions in Water than in Acid. Hence à dilution will increase OH conc.
Pls correct me i am wrong
My reasoning is that the shift cannot fully compensate for the initial dilution?
Yes I agree, only a partial change. Everything is still more diluted so everything decreases in concentration.
Post by: lil_stace on November 11, 2010, 12:42:16 pm
Does anyone else remember getting 3.84% as the percentage ionisation for the lactic acid thing?
I got around that, i think 3.79% (i THINK), but it was probably dependent on whether we rounded or carried over our calculations from the previous step
yeah i also got around 3.79%
i got 3.84% i think it varies on the rounding you use, i didn't round it till the end, so don't worry either way you should get full marks for it
Post by: Linkage1992 on November 11, 2010, 12:42:58 pm
Post by: Xavier1234 on November 11, 2010, 12:43:23 pm
I got this 3.79 figure i think aswell.
I dont think the calculation questions were that much of a problem.
Xavier I'm pretty sure it wasnt lower than SC because the temperature used was 190 degrees ( 165 above SC)
oooo missed that. =S
Post by: Whatlol on November 11, 2010, 12:43:41 pm
3.74 ^
yup got this.
what did you get for volume of hydrogen? was it around 6.2 L
Post by: Xavier1234 on November 11, 2010, 12:43:58 pm
thank god. i thought my answer of 3.XX% was too low.
its a weak acid so its gonna be low :)
Post by: mirra250 on November 11, 2010, 12:44:03 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Post by: doter on November 11, 2010, 12:44:13 pm
Does anyone else remember getting 3.84% as the percentage ionisation for the lactic acid thing?
I got around that, i think 3.79% (i THINK), but it was probably dependent on whether we rounded or carried over our calculations from the previous step
yeah i also got around 3.79%
i got 3.84% i think it varies on the rounding you use, i didn't round it till the end, so don't worry either way you should get full marks for it
What!! Damn I got 0.0017% or something. Crap I've lost so much more marks then ive gotten :(
Post by: Xavier1234 on November 11, 2010, 12:44:27 pm
3.74 ^
yup got this.
what did you get for volume of hydrogen? was it around 6.2 L
i got 6.2L for H2 as well
Post by: sajib_mostofa on November 11, 2010, 12:44:32 pm
3.74 ^
yup got this.
what did you get for volume of hydrogen? was it around 6.2 L
Thats what I got as well
Post by: jimmy999 on November 11, 2010, 12:45:14 pm
Note: You always need to find a way to incorporate the term explosions into a Chemistry exam
Post by: Studyinghard on November 11, 2010, 12:45:17 pm
Post by: Studyinghard on November 11, 2010, 12:45:55 pm
In case this answer to the calorimeter question about oxygen being pumped to high pressure hasn't been stated yet, but if I did the exam, I would've written that the calorimeter is a bomb and is meant to act like a bomb. Hence the small container with benzoic acid needs to explode in a quick reaction. This happens best at high pressures and high oxygen concentrations.
Note: You always need to find a way to incorporate the term explosions into a Chemistry exam
i think I wrote that =/ I said the high pressures would increase the rate of reaction, good enough ?
Post by: Linkage1992 on November 11, 2010, 12:46:01 pm
thank god. i thought my answer of 3.XX% was too low.
its a weak acid so its gonna be low :)
i didn't notice that, and that's why i'm going to get like a low 30 ss. chem just doesn't come to me like math based subjects.
Post by: lisafaustina on November 11, 2010, 12:46:13 pm
Post by: 98.40_for_sure on November 11, 2010, 12:46:30 pm
i said the one with high pressure oxygen is so incomplete combustion cant happen lol fml
Post by: Shark 774 on November 11, 2010, 12:46:55 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
Post by: Studyinghard on November 11, 2010, 12:47:16 pm
Post by: 10weid on November 11, 2010, 12:47:38 pm
3.74 ^
yup got this.
what did you get for volume of hydrogen? was it around 6.2 L
i got 6.2L for H2 as well
+1
Post by: doter on November 11, 2010, 12:48:07 pm
Post by: andy456 on November 11, 2010, 12:48:58 pm
What was the prediction made by everyone in 2iv). I just said the prediction was the concentration of H+ and the ionised lactic acid would be the sameI said that because lactic acid was extremely weak we could use its initial conc in calculations despite it reacting to a small extent
Post by: 98.40_for_sure on November 11, 2010, 12:49:06 pm
Post by: Shark 774 on November 11, 2010, 12:49:12 pm
What was the prediction made by everyone in 2iv). I just said the prediction was the concentration of H+ and the ionised lactic acid would be the same
I said you assume that the number of moles of undissolved acid is the same as the number of moles of acid after it's been dissolved.
Post by: curious111 on November 11, 2010, 12:49:17 pm
What did u guys get for that lithium metal question, exploding with water. I had no idea
I said something about the reaction producing H2, and this could somehow cause an explosion. No idea TBH.
Post by: 10weid on November 11, 2010, 12:49:24 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
im fairly sure 19 is D, as recharging of fuel cells and recharging of secondary cells both result in the conversion of electrical energy to chemical energy?
Post by: mirra250 on November 11, 2010, 12:50:01 pm
none!! VCAA effed up :) All of the answers were wrong.No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
Post by: whyareyoureadingthis on November 11, 2010, 12:50:11 pm
I said that I assumed the lactic acid did not ionise to a great extent.What was the prediction made by everyone in 2iv). I just said the prediction was the concentration of H+ and the ionised lactic acid would be the sameI said that because lactic acid was extremely weak we could use its initial conc in calculations despite it reacting to a small extent
Post by: Studyinghard on November 11, 2010, 12:50:18 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
im fairly sure 19 is D, as recharging of fuel cells and recharging of secondary cells both result in the conversion of electrical energy to chemical energy?
fuel cells are non rechargeable
Post by: Shark 774 on November 11, 2010, 12:50:24 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
im fairly sure 19 is D, as recharging of fuel cells and recharging of secondary cells both result in the conversion of electrical energy to chemical energy?
But I thought the whole reason for a fuel cell was to not recharge...
Post by: sajib_mostofa on November 11, 2010, 12:50:28 pm
No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
im fairly sure 19 is D, as recharging of fuel cells and recharging of secondary cells both result in the conversion of electrical energy to chemical energy?
You can't recharge a fuel cell though
Post by: 10weid on November 11, 2010, 12:50:30 pm
What did u guys get for that lithium metal question, exploding with water. I had no idea
I said something about the reaction producing H2, and this could somehow cause an explosion. No idea TBH.
gas accumulates, potentially leading to explosion..was in STAV 10 practice exam..
Post by: Whatlol on November 11, 2010, 12:50:57 pm
Post by: jayna on November 11, 2010, 12:51:13 pm
Fuel cells are not recharged =\No they didnt say through. this is the exact answer (i have the exam):i got 19 C reactants are not stored in a fuel cell....C is untrue (just like all of the answers, they stuffed up).
C stated that the electrons went from the reductant to the anode. The electrons go to the CATHODE, never to the anode
I thought it said electrons flow from the reductant through the anode, which would be true because they have to flow through the anode and then the external circuit before they get to the cathode.
C. Electrons pass from the reductant to the anode as electricity is produced.
Ah ok, so what was the right answer?
im fairly sure 19 is D, as recharging of fuel cells and recharging of secondary cells both result in the conversion of electrical energy to chemical energy?
Post by: Studyinghard on November 11, 2010, 12:51:18 pm
I just said concentration of H30+ = concentration of lacitic acid ions or w/e
I hope this is right :D
Post by: mirra250 on November 11, 2010, 12:51:24 pm
It makes Li2O and H2 gas yeah? and h2 is highly combustible in air? hence BOOM?that's what i did! and i mentioned that it may be exothermic, so the energy released initiated the explosion of the h2 gas
Post by: 10weid on November 11, 2010, 12:51:54 pm
just because they are not recharged in practice, doesnt mean they cant be recharged..
Post by: Shark 774 on November 11, 2010, 12:51:57 pm
What did u guys get for that lithium metal question, exploding with water. I had no idea
I said something about the reaction producing H2, and this could somehow cause an explosion. No idea TBH.
gas accumulates, potentially leading to explosion..was in STAV 10 practice exam..
The gas combusts due to the heat released by the reaction is what I wrote.
Post by: Studyinghard on November 11, 2010, 12:52:27 pm
Post by: mirra250 on November 11, 2010, 12:53:02 pm
I just said concentration of H30+ = concentration of lacitic acid ions or w/ei said that all of the lactic acid dissolved in the water... simple but i hope correct?
Post by: qshyrn on November 11, 2010, 12:53:08 pm
GAS PRODUCED= HIGH PRESSURE = BATTERY BURSTSWhat did u guys get for that lithium metal question, exploding with water. I had no idea
I said something about the reaction producing H2, and this could somehow cause an explosion. No idea TBH.
gas accumulates, potentially leading to explosion..was in STAV 10 practice exam..
The gas combusts due to the heat released by the reaction is what I wrote.
Post by: Shark 774 on November 11, 2010, 12:53:21 pm
WHICH REACTANT WAS IN EXCESS QUESTION. the one where you mix urea and water. did everyone say water and reason because the reaction will completely occur with the urea
Yes I said to give a greater percentage conversion of urea to whatever the other one was.
Post by: Studyinghard on November 11, 2010, 12:53:27 pm
fuel cells CAN be recharged.... thus only D is correct...
just because they are not recharged in practice, doesnt mean they cant be recharged..
a new twist, i like it.
Post by: doter on November 11, 2010, 12:54:13 pm
WHICH REACTANT WAS IN EXCESS QUESTION. the one where you mix urea and water. did everyone say water and reason because the reaction will completely occur with the urea
Yeh I wrote water but u didn't have to give a reason, did you?
Post by: 98.40_for_sure on November 11, 2010, 12:54:27 pm
WHICH REACTANT WAS IN EXCESS QUESTION. the one where you mix urea and water. did everyone say water and reason because the reaction will completely occur with the urea
Water to ensure that all of the piss will react into products
Post by: Shark 774 on November 11, 2010, 12:55:03 pm
fuel cells CAN be recharged.... thus only D is correct...
just because they are not recharged in practice, doesnt mean they cant be recharged..
a new twist, i like it.
I hate it, stupid VCAA. A lot of the reasoning behind unit 4 is putting chemistry into practice in the real world/industries. Then they ask a question that is just possible, not practical. GRR! :(
Post by: mankay on November 11, 2010, 12:55:19 pm
I just said concentration of H30+ = concentration of lacitic acid ions or w/e
I hope this is right :D
Im fairly sure thats not an assumption, its a fact.
I said that you assume the change in [lactic acid] is neglible
Post by: lisafaustina on November 11, 2010, 12:55:58 pm
Post by: _henwee on November 11, 2010, 12:56:02 pm
WHICH REACTANT WAS IN EXCESS QUESTION. the one where you mix urea and water. did everyone say water and reason because the reaction will completely occur with the urea
Water to ensure that all of the piss will react into products
Such a nice way to put it. ^^"
Post by: lisafaustina on November 11, 2010, 12:56:38 pm
Post by: whyareyoureadingthis on November 11, 2010, 12:56:46 pm
GAS PRODUCED= HIGH PRESSURE = BATTERY BURSTSThis.
2Li(s) + 2H2O(l) ---> 2LiOH(aq) + H2(g)
...or that's what I got anyway. Correct it if necessary.
Post by: andy456 on November 11, 2010, 12:57:54 pm
wrote the wrong equation
Post by: 10weid on November 11, 2010, 12:58:38 pm
I just said concentration of H30+ = concentration of lacitic acid ions or w/e
I hope this is right :D
Im fairly sure thats not an assumption, its a fact.
I said that you assume the change in [lactic acid] is neglible
i said the assumption is that all of the lactic acid dissolves in the solution...
Post by: kenhung123 on November 11, 2010, 01:00:08 pm
Post by: whyareyoureadingthis on November 11, 2010, 01:00:16 pm
Damn.... i stuffed up the lithium water question.........Don't take my answer as the right one necessarily... just what I got.
wrote the wrong equation
Post by: 98.40_for_sure on November 11, 2010, 01:00:50 pm
Post by: Studyinghard on November 11, 2010, 01:00:56 pm
Post by: 10weid on November 11, 2010, 01:02:03 pm
Does anyone remember their CF value. i got 12494.05 J/C-1
yeahhhh i got 12.5 KJ per C
Post by: andy456 on November 11, 2010, 01:02:39 pm
Does anyone remember their CF value. i got 12494.05 J/C-1yeah but that was the sig fig question so i put 12.5kJ/C-1
Post by: Studyinghard on November 11, 2010, 01:02:44 pm
Post by: qshyrn on November 11, 2010, 01:03:01 pm
Q5d
"Acceptable responses included:
• fuel cells are not rechargeable"
I DID THIS EXAM JUST BEFORE GOING IN, AND I BASED MY ANSWER ON THIS!!!!!!!!!!!!!
Post by: sajib_mostofa on November 11, 2010, 01:03:14 pm
nice and mass of lithium was 80.3 grams?Yeah
Post by: vexx on November 11, 2010, 01:03:21 pm
and my CF was same as your studyinghard, just in kj/c
Post by: scocliffe09 on November 11, 2010, 01:04:20 pm
AHEM... VCAA WOULD NOT WANNA LOOK BAD AFTER WHAT THEY WROTE LAST YEAR:Yes it has to be C I think. The electrons DO pass from reductant to anode, and THEN to the cathode.
Q5d
"Acceptable responses included:
• fuel cells are not rechargeable"
Also got 12.5kJ/C.
Post by: 10weid on November 11, 2010, 01:05:08 pm
coz none of the answers are right... i still maintain its D though, coz electrons always flow to the cathode :/
Post by: Studyinghard on November 11, 2010, 01:07:08 pm
Post by: curious111 on November 11, 2010, 01:07:25 pm
Post by: kenhung123 on November 11, 2010, 01:07:41 pm
Post by: mirra250 on November 11, 2010, 01:09:29 pm
Not necessarily. What is the reductant is Fe (s)? It would be the reductant AND the anode, so the electrons couldnt pass to itself!! Question 19 is wrong. Full stopAHEM... VCAA WOULD NOT WANNA LOOK BAD AFTER WHAT THEY WROTE LAST YEAR:Yes it has to be C I think. The electrons DO pass from reductant to anode, and THEN to the cathode.
Q5d
"Acceptable responses included:
• fuel cells are not rechargeable"
Also got 12.5kJ/C.
Post by: mustafa on November 11, 2010, 01:11:51 pm
Seriosly....
C is Most DEFINITELY wring. C States that electrines Flow from Anode to Anode.....
Thats doubly WRong...
Post by: doter on November 11, 2010, 01:13:29 pm
Does anyone remember their CF value. i got 12494.05 J/C-1yeah but that was the sig fig question so i put 12.5kJ/C-1
For this question, was it two or three sig figure? Cause I wasn't sure if the 25atm counted as sig figures?
Post by: Whatlol on November 11, 2010, 01:14:06 pm
didnt think the 25atm matters, since it wasnt used for calculationsDoes anyone remember their CF value. i got 12494.05 J/C-1yeah but that was the sig fig question so i put 12.5kJ/C-1
For this question, was it two or three sig figure? Cause I wasn't sure if the 25atm counted as sig figures?
Post by: 8039 on November 11, 2010, 01:15:02 pm
oh yeah i got 3.74% for the ionization now that i remember (well close enough)
and my CF was same as your studyinghard, just in kj/c
Oh shit I got 0.01% for the lactic acid question :(
Post by: mustafa on November 11, 2010, 01:15:51 pm
Post by: doter on November 11, 2010, 01:16:21 pm
I did mine to two sig figures. So it's wrong?didnt think the 25atm matters, since it wasnt used for calculationsDoes anyone remember their CF value. i got 12494.05 J/C-1yeah but that was the sig fig question so i put 12.5kJ/C-1
For this question, was it two or three sig figure? Cause I wasn't sure if the 25atm counted as sig figures?
Post by: will74 on November 11, 2010, 01:23:29 pm
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidised
Post by: jasoN- on November 11, 2010, 01:23:44 pm
at first i had 1.25 x 10^4, but i rounded the no. moles off too early and so changed it to this.
i got 80.3g for lithium
FML i got both the "poisioned catalyst" ones wrong, so trippy and was thinking too much.
and for the reactants have more particles than products, i did less but i changed it from the right answer!! :(
The very last question was so EASY!
Post by: stonecold on November 11, 2010, 01:24:27 pm
Q 19 was stupid....
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidised
This is what I though. The rest were all wrong...
Post by: mirra250 on November 11, 2010, 01:30:37 pm
Q 19 was stupid....And if solid iron were the reductant? This wouldnt happen as the iron would be the reductant AND the anode. Electrons cannot pass to itself. All answers are wrong
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidised
Post by: Studyinghard on November 11, 2010, 01:35:24 pm
Post by: andy456 on November 11, 2010, 01:36:47 pm
Q 19 was stupid....And if solid iron were the reductant? This wouldnt happen as the iron would be the reductant AND the anode. Electrons cannot pass to itself. All answers are wrong
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidised
no dont worry im wrong.... this is confusing me
Post by: chem-nerd on November 11, 2010, 01:39:01 pm
Not necessarily. What is the reductant is Fe (s)? It would be the reductant AND the anode, so the electrons couldnt pass to itself!! Question 19 is wrong. Full stop
Don't forget the context of this question. Can you give an example of a fuel cell or a rechargeable cell where the reductant and anode are both Fe(s)?
Post by: mirra250 on November 11, 2010, 01:39:10 pm
lol it's confusing you because none of the answers are right.Q 19 was stupid....reductant? This wouldnt happen as the iron would be the reductant AND the anode. Electrons cannot pass to itself. All answers are wrong
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidisedno aquous Fe would be the reductant and solid Fe would be the anode....chill im sure everyone struggled with the question...
no dont worry im wrong.... this is confusing me
Post by: mustafa on November 11, 2010, 01:39:27 pm
A could also be correct as a portion of reactants are within a fuel
cell. The pumping if additional reactants is only an extension to the cell.
It's A or D. Do Not Be STUPID and STUPIDLY argue the STUPID option C, which STUPIDLY states that STUPID electrons flow to the STUPID anode. Coz that is impossible.
Post by: stonecold on November 11, 2010, 01:40:32 pm
Q 19 was stupid....And if solid iron were the reductant? This wouldnt happen as the iron would be the reductant AND the anode. Electrons cannot pass to itself. All answers are wrong
But TECHNICALLY, electrons do flow from the reductant to the anode. As the reductant itself is oxidisedno aquous Fe would be the reductant and solid Fe would be the anode....chill im sure everyone struggled with the question...
no dont worry im wrong.... this is confusing me
Pretty confident that is 19 is C and there is no error.
Reductant is oxidised. Electrons are produced. The cant flow directly to the cathode. They go through the anode 1st.
D is plain wrong unfortunately. You can't recharge a fuel cell as the products escape. It is impossible.
Screwed up MC Q7. Pretty happy with everything else though. :)
Post by: mirra250 on November 11, 2010, 01:41:05 pm
no but that is beside the point. it theoretically could be done.Not necessarily. What is the reductant is Fe (s)? It would be the reductant AND the anode, so the electrons couldnt pass to itself!! Question 19 is wrong. Full stop
Don't forget the context of this question. Can you give an example of a fuel cell or a rechargeable cell where the reductant and anode are both Fe(s)?
Post by: 99.95Bitches on November 11, 2010, 01:41:47 pm
pretty sure 19 was A.I think so to
i am pretty sure it has to be D
because in one of the exams i did the fuel cell could be recharged.
and also ABC are all wrong becuase fuel cells require continous reactants
Post by: meefz on November 11, 2010, 01:42:18 pm
Post by: Studyinghard on November 11, 2010, 01:43:20 pm
Post by: meefz on November 11, 2010, 01:44:04 pm
Post by: mustafa on November 11, 2010, 01:44:30 pm
explain how on earth is it possible to have electrons flow to the anode????
Post by: happycat on November 11, 2010, 01:44:34 pm
nice and mass of lithium was 80.3 grams?I had that but I went by number of sig figs and said 80 grams since Li in data sheet was 6.9, 2 two sig figs which was the least number of them
Post by: darkphoenix on November 11, 2010, 01:44:41 pm
What did people get for the balanced complete combustion of benzoic acid???
Fkn balancing too ages!! LOL
Hm i think overall it wasn't too bad, considering i barely studied for it (2 prac exams) and had around 6.5 hrs of sleep. I agree that some questions were weird though.
Post by: jasoN- on November 11, 2010, 01:44:54 pm
Post by: vexx on November 11, 2010, 01:44:58 pm
wait, wasnt the mole for oxygen 15?
yeah i got 15 too, since the right side had 34 Oxygens, where 4 were taken out by benzoic itself.
Post by: mustafa on November 11, 2010, 01:45:32 pm
Post by: andy456 on November 11, 2010, 01:45:39 pm
Christ, someone with brains plsIn Mao's topic he explained why he believed it was C... go and have a read of it and move on..........
explain how on earth is it possible to have electrons flow to the anode????
Post by: vexx on November 11, 2010, 01:46:39 pm
2C6H5COOH + 13O2 -> 12CO2 + 6H2O delta(H) = -6454
you missed a C, there are 7 carbons in benzoic acid, hence 14 are needed on the other side after doubling it
Post by: jasoN- on November 11, 2010, 01:47:15 pm
wait my delta H is still right yes?
Post by: meefz on November 11, 2010, 01:47:41 pm
Was i meant to use the 3227 or the 6454 in my calculations, cause i used 6454.
i think im wrong. :(
Post by: vexx on November 11, 2010, 01:47:55 pm
OH FUCK MY LFE!
you'll get 2/3 if you did correct states.
Post by: stonecold on November 11, 2010, 01:48:37 pm
Christ, someone with brains plsIn Mao's topic he explained why he believed it was C... go and have a read of it and move on..........
explain how on earth is it possible to have electrons flow to the anode????
because they have to go through the circuit, and can't go through the solution.
thought it was rather simple.
this q will save my ass for my dumb mistake on Q7... :D
Post by: andy456 on November 11, 2010, 01:49:24 pm
in the calculations i used the undoubled number... is that wrong??
Post by: stonecold on November 11, 2010, 01:49:41 pm
ok for the benxoic question i forgot to double the the delta H...
in the calculations i used the undoubled number... is that wrong??
no.
Post by: happycat on November 11, 2010, 01:49:47 pm
Post by: mirra250 on November 11, 2010, 01:50:26 pm
2C6H5COOH + 13O2 -> 12CO2 + 6H2O delta(H) = -6454wrong. you have 14 C on the left, 12 on the right.
The real equation is
2C6H5COOH + 15O2 -> 14CO2 + 6H2O delta(H) = -6454
Post by: stonecold on November 11, 2010, 01:50:47 pm
Was I supposed to say that mass of lithium was 80.3 or just 80 I went by least number of sig figs that was for litium in data sheet? Will I be penalised for not having correct number of sig figs?
I also put 80g. According to the exam report in 2008, you take into account sig figs of molar masses.
Post by: andy456 on November 11, 2010, 01:51:00 pm
So i had to multiply the n(benzoic) by 3227ok for the benxoic question i forgot to double the the delta H...
in the calculations i used the undoubled number... is that wrong??
no.
Post by: kenhung123 on November 11, 2010, 01:51:29 pm
Post by: happycat on November 11, 2010, 01:52:06 pm
Well thanx you :)Was I supposed to say that mass of lithium was 80.3 or just 80 I went by least number of sig figs that was for litium in data sheet? Will I be penalised for not having correct number of sig figs?I also put 80g. According to the exam report in 2008, you take into account sig figs of molar masses.
Post by: 98.40_for_sure on November 11, 2010, 01:52:21 pm
Post by: kenhung123 on November 11, 2010, 01:52:24 pm
Yea, however if you did ratios, you would have made 2 moles benzoic =double heat of combustionSo i had to multiply the n(benzoic) by 3227ok for the benxoic question i forgot to double the the delta H...
in the calculations i used the undoubled number... is that wrong??
no.
Post by: darkphoenix on November 11, 2010, 01:53:52 pm
You didn't have to double the Oxygens in that balancing did ya? i think i left it as 7.5
Yeah same here. I think you can do either, i remember in assessment reports in previous years they accepted both.
Post by: 8039 on November 11, 2010, 01:54:18 pm
What did people get for the balanced complete combustion of benzoic acid???
I got 2 mol
Post by: monicapham93 on November 11, 2010, 02:16:14 pm
ALTHOUGH i stupidly got that replace E values wrong
i thought i worked it out to be Cd = +.22V
but i was completely off track :(
Post by: garliczombie on November 11, 2010, 02:17:28 pm
Post by: Stroodle on November 11, 2010, 02:47:38 pm
Was I supposed to say that mass of lithium was 80.3 or just 80 I went by least number of sig figs that was for litium in data sheet? Will I be penalised for not having correct number of sig figs?
I also put 80g. According to the exam report in 2008, you take into account sig figs of molar masses.
Man that's annoying. In The Age, before the mid year, there was an article where the chief examiner said that molar mass sig figs shouldn't affect your answer's sig figs. So ever since then I've gone by this..
Post by: crunch 29 on November 11, 2010, 03:00:58 pm
AgCl.... = +0.22V ?
Post by: ghadz7 on November 11, 2010, 03:03:00 pm
Post by: stonecold on November 11, 2010, 03:04:05 pm
Post by: 8039 on November 11, 2010, 03:07:25 pm
what was the correct E naught value ?
AgCl.... = +0.22V ?
I was confused... in experiment 3 hydrogen acts as a reductant... but has a 0.00V so wtf
Post by: bubsy on November 11, 2010, 03:34:13 pm
This was my reasoning: Although the direction of electron through the wire is from anode to cathode, the anode is the site of oxidation, the loss of electrons from the reductant. These electrons are taken up by the anode (bad terminology :P) and are then conducted to the cathode. All of the others looked completely wrong to me.THis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
Post by: bubsy on November 11, 2010, 03:36:36 pm
I don't think the reductant has to be the anode. The anode could be an inert electrode and the reductant could be a species in the solution.Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:Dont think so Its clearly CTHis is what i think.for question 19 i said A beacuse the reactants ARE stored within the fuel cell regardless of whether it is pumped continuously. all the other possible answers were plain wrong...so yeah.they aren't stored. they are PUMPED IN - hence they were never originally stored in the cell. but i repeat, ALL ANSWERS WERE WRONG FOR Q19
hope i'm right.
i said biochemical was more sustainable cos its renewable?
Technically electrons do pass from the reductant to the anode though? Anode is just negative electrode?
Reductant (site of oxidation) is the anode. How the hell do electrons go from anode to anode.
LOL that post cracked me up. its A guys. :2funny:
um the reductant is the anode.... so it's clearly not C
Post by: bubsy on November 11, 2010, 03:40:42 pm
Post by: bubsy on November 11, 2010, 03:43:09 pm
Ummmmm, guys seriosuly....The concentrations of H+ and OH- in water are equal. So if the concentration of OH- increases due to the addition of water, it would make sense that H+ increased correspondingly as well. The degree of self ionisation of water is so negligible that I'm pretty sure the OH- decreases as well as the H+. idk, I could be wrong.
For that dilution question the [H+] decreases and the [OH-] OBViOusly INCREASES.
There is à higher concentration of OH Ions in Water than in Acid. Hence à dilution will increase OH conc.
Pls correct me i am wrong
Post by: brett011 on November 11, 2010, 03:57:01 pm
Post by: aznanthony on November 11, 2010, 04:05:32 pm
Post by: bubsy on November 11, 2010, 04:15:32 pm
Christ, someone with brains plsSeriously? Are you really going to get this agro over a one mark multiple choice question? If electrons flow from anode to cathode, they do so through the wire. The electrons don't materialise out of thin air (or thin water, given it was a solution). Oxidation is the loss of electrons and since the anode is the site of oxidation, it seems most sensible to me that the reductant, which is OXIDISED, donates its electrons TO the anode, which then passes it on to the cathode. This is my reasoning, fault it if you will but do so in a civil manner.
explain how on earth is it possible to have electrons flow to the anode????
I also think that it would be profoundly unfair of VCAA to explicitly state one year that fuel cells are not rechargeable and to then expect students to know that they are theoretically rechargeable and work this into a multiple choice question.
As for the situation with solid iron acting as the anode, I'm not entirely sure about the mechanics of this, but seeing as electrons are delocalised in metals anyway, I would simply assume that the production of electrons during oxidation would still be transmitted through the iron, even if it were itself being oxidised in the process.
I'm not particularly good at chemistry, so I chose the option that struck me as being the most logical.
Post by: bubsy on November 11, 2010, 04:16:50 pm
haha me too, i did six exams and had about 5 hours of sleep, but i also had two spoonfuls of instant coffee mixed with a teeny bit of hot water before my exam... it made me jittery,.What did people get for the balanced complete combustion of benzoic acid???
Fkn balancing too ages!! LOL
Hm i think overall it wasn't too bad, considering i barely studied for it (2 prac exams) and had around 6.5 hrs of sleep. I agree that some questions were weird though.
Post by: jasoN- on November 11, 2010, 04:18:26 pm
Post by: cama23 on November 11, 2010, 04:19:41 pm
Post by: m@tty on November 11, 2010, 04:24:34 pm
for question 8a) is it alright to say "fuel cells are only ~60-70% efficient, hence less voltage produced"
That's basically what I said. "In fuel cells there are energy losses to heat and other forms, thus reducing the voltage produced."
Post by: liv on November 11, 2010, 04:31:17 pm
haha me too, i did six exams and had about 5 hours of sleep, but i also had two spoonfuls of instant coffee mixed with a teeny bit of hot water before my exam... it made me jittery,.What did people get for the balanced complete combustion of benzoic acid???
Fkn balancing too ages!! LOL
Hm i think overall it wasn't too bad, considering i barely studied for it (2 prac exams) and had around 6.5 hrs of sleep. I agree that some questions were weird though.
i onbly had two hours of sleep last night...because my brain didn't want to switch off. it then took me ages this morning to understand what the questions were asking...
and then when it came to the balancing....bleurgh.
Post by: samiira on November 11, 2010, 04:32:42 pm
my sleep deprivation screwed me up too :/haha me too, i did six exams and had about 5 hours of sleep, but i also had two spoonfuls of instant coffee mixed with a teeny bit of hot water before my exam... it made me jittery,.What did people get for the balanced complete combustion of benzoic acid???
Fkn balancing too ages!! LOL
Hm i think overall it wasn't too bad, considering i barely studied for it (2 prac exams) and had around 6.5 hrs of sleep. I agree that some questions were weird though.
i onbly had two hours of sleep last night...because my brain didn't want to switch off. it then took me ages this morning to understand what the questions were asking...
and then when it came to the balancing....bleurgh.
Post by: happycat on November 11, 2010, 04:35:58 pm
Post by: meth lab future on November 12, 2010, 03:33:45 pm
Post by: stonecold on November 12, 2010, 03:41:49 pm
Im so peved at our person that like looked over us doing the exam, because on Q6 she said that the Eo values were wrong so we had to make them all negative, but it was just supposed to be the acutal electrons in the equations, grrrr so pissed coz know i got it wrong, they shouldnt be able to make marks wrong for that coz its not my fault, I wanna complain!!!!!
Look, there are numerous people who got fucked over by this. You should all get together, and go to VCAA and just not leave until they agree to give the marks or remove the question. Make a petition. Don't just winge on here. Make sure something is done about it. :)
Moreover, go to the newspaper and do to VCAA what that girl did to IGGS.
My mum works at the CBA and her branch was in an article yesterday because one of the customers had a sook about no miniutes silence, and one of the staff members told him that they could not stop working, so he threatened to go to the Herald Sun and quoted what she said, and they put it in an article ROFL.
If this rubbish can make the newspaper, then this, which is far more important, should easily be reported.
Nothing would thrill me more than to see an article in the newspaper listing out all of VCAA's stuff ups, including the dance exam in the chem exam data book, the missing MC answer sheets for several exams, and the electron debacle which happened yesterday.
Some media pressure might get them to clean up their act.
Post by: liv on November 12, 2010, 03:50:47 pm
+1Im so peved at our person that like looked over us doing the exam, because on Q6 she said that the Eo values were wrong so we had to make them all negative, but it was just supposed to be the acutal electrons in the equations, grrrr so pissed coz know i got it wrong, they shouldnt be able to make marks wrong for that coz its not my fault, I wanna complain!!!!!
Look, there are numerous people who got fucked over by this. You should all get together, and go to VCAA and just not leave until they agree to give the marks or remove the question. Make a petition. Don't just winge on here. Make sure something is done about it. :)
Moreover, go to the newspaper and do to VCAA what that girl did to IGGS.
My mum works at the CBA and her branch was in an article yesterday because one of the customers had a sook about no miniutes silence, and one of the staff members told him that they could not stop working, so he threatened to go to the Herald Sun and quoted what she said, and they put it in an article ROFL.
If this rubbish can make the newspaper, then this, which is far more important, should easily be reported.
Nothing would thrill me more than to see an article in the newspaper listing out all of VCAA's stuff ups, including the dance exam in the chem exam data book, the missing MC answer sheets for several exams, and the electron debacle which happened yesterday.
Some media pressure might get them to clean up their act.
Post by: stonecold on November 12, 2010, 03:54:45 pm
+1Im so peved at our person that like looked over us doing the exam, because on Q6 she said that the Eo values were wrong so we had to make them all negative, but it was just supposed to be the acutal electrons in the equations, grrrr so pissed coz know i got it wrong, they shouldnt be able to make marks wrong for that coz its not my fault, I wanna complain!!!!!
Look, there are numerous people who got fucked over by this. You should all get together, and go to VCAA and just not leave until they agree to give the marks or remove the question. Make a petition. Don't just winge on here. Make sure something is done about it. :)
Moreover, go to the newspaper and do to VCAA what that girl did to IGGS.
My mum works at the CBA and her branch was in an article yesterday because one of the customers had a sook about no miniutes silence, and one of the staff members told him that they could not stop working, so he threatened to go to the Herald Sun and quoted what she said, and they put it in an article ROFL.
If this rubbish can make the newspaper, then this, which is far more important, should easily be reported.
Nothing would thrill me more than to see an article in the newspaper listing out all of VCAA's stuff ups, including the dance exam in the chem exam data book, the missing MC answer sheets for several exams, and the electron debacle which happened yesterday.
Some media pressure might get them to clean up their act.
I am tempted to email them links to all these comments about people getting screwed over. They will report anything haha :)
Post by: happycat on November 12, 2010, 04:41:45 pm
This stupid thing about the e missing the -ve sign I'm so over it lets stop the winging about it, I didn't even notice. It's over now so we all need to chill out and get over it ;)+1Im so peved at our person that like looked over us doing the exam, because on Q6 she said that the Eo values were wrong so we had to make them all negative, but it was just supposed to be the acutal electrons in the equations, grrrr so pissed coz know i got it wrong, they shouldnt be able to make marks wrong for that coz its not my fault, I wanna complain!!!!!
Look, there are numerous people who got fucked over by this. You should all get together, and go to VCAA and just not leave until they agree to give the marks or remove the question. Make a petition. Don't just winge on here. Make sure something is done about it. :)
Moreover, go to the newspaper and do to VCAA what that girl did to IGGS.
My mum works at the CBA and her branch was in an article yesterday because one of the customers had a sook about no miniutes silence, and one of the staff members told him that they could not stop working, so he threatened to go to the Herald Sun and quoted what she said, and they put it in an article ROFL.
If this rubbish can make the newspaper, then this, which is far more important, should easily be reported.
Nothing would thrill me more than to see an article in the newspaper listing out all of VCAA's stuff ups, including the dance exam in the chem exam data book, the missing MC answer sheets for several exams, and the electron debacle which happened yesterday.
Some media pressure might get them to clean up their act.
I am tempted to email them links to all these comments about people getting screwed over. They will report anything haha :)
Post by: stonecold on November 12, 2010, 05:17:59 pm
This stupid thing about the e missing the -ve sign I'm so over it lets stop the winging about it, I didn't even notice. It's over now so we all need to chill out and get over it ;)+1Im so peved at our person that like looked over us doing the exam, because on Q6 she said that the Eo values were wrong so we had to make them all negative, but it was just supposed to be the acutal electrons in the equations, grrrr so pissed coz know i got it wrong, they shouldnt be able to make marks wrong for that coz its not my fault, I wanna complain!!!!!
Look, there are numerous people who got fucked over by this. You should all get together, and go to VCAA and just not leave until they agree to give the marks or remove the question. Make a petition. Don't just winge on here. Make sure something is done about it. :)
Moreover, go to the newspaper and do to VCAA what that girl did to IGGS.
My mum works at the CBA and her branch was in an article yesterday because one of the customers had a sook about no miniutes silence, and one of the staff members told him that they could not stop working, so he threatened to go to the Herald Sun and quoted what she said, and they put it in an article ROFL.
If this rubbish can make the newspaper, then this, which is far more important, should easily be reported.
Nothing would thrill me more than to see an article in the newspaper listing out all of VCAA's stuff ups, including the dance exam in the chem exam data book, the missing MC answer sheets for several exams, and the electron debacle which happened yesterday.
Some media pressure might get them to clean up their act.
I am tempted to email them links to all these comments about people getting screwed over. They will report anything haha :)
That is not the problem.
Some stupid exam supervisors gave students the wrong directive, and told them to change the E naught value, which was detrimental to their answer.
They work for VCAA, and have a lot to answer for.
Post by: happycat on November 12, 2010, 06:01:26 pm
Post by: m@tty on November 12, 2010, 06:07:33 pm
This could end up in the Herald Sun lol
Ohh nooo. No one will take it seriously if it does.. :(
Post by: stonecold on November 12, 2010, 06:44:04 pm
This could end up in the Herald Sun lol
Ohh nooo. No one will take it seriously if it does.. :(
true that!
a current affair is our highly reputable medium of choice to break this injustice to the public :P
Post by: Russ on November 12, 2010, 06:46:44 pm
It's a fairly standard thing to do when there are errors in papers
Post by: Studyinghard on November 12, 2010, 06:59:22 pm
Contact the VCAA and they'll either scrap the question or award marks for using the wrong E0 value.
It's a fairly standard thing to do when there are errors in papers
they will NEVER scrap the question.
Post by: m@tty on November 12, 2010, 07:50:04 pm
Post by: Whatlol on November 12, 2010, 07:51:17 pm
What I don't understand is what on earth you did if all of thevalues were negative?? I mean, you could only deduce that the E naught value of silver half cell was higher than that of the hydrogen half cell from the experimental results. (that is, it was positive)...
i was just like well the least negative one will be the one that reacted... even tho it doesnt make sense, and wrote -0.22 V for silver
Post by: m@tty on November 12, 2010, 08:00:21 pm
Post by: Whatlol on November 12, 2010, 08:01:48 pm
Oh okay. Haha, well I guess you had to do something.
yea :P
Post by: Davoo! on November 14, 2010, 01:37:27 pm
Wish I could say the same... :\ Lost probably 15-20 marks ahaha.
Post by: lisafaustina on November 14, 2010, 03:43:57 pm
Post by: happycat on November 14, 2010, 03:53:34 pm
Wow, seems it was a piss easy exam for everyone.I feel that I would've lost about that much. I did think it was easy though.
Wish I could say the same... :\ Lost probably 15-20 marks ahaha.