Post by: magnum on November 12, 2009, 12:41:31 pm
How did everyone find the Unit 4 exam? ???
Post by: kenny17 on November 12, 2009, 12:43:04 pm
Post by: angelboykevin on November 12, 2009, 12:46:41 pm
Post by: TheJosh on November 12, 2009, 12:48:42 pm
lol,, never ever ever ever did so good for chem!!!^^
true dat 8-)
Post by: tommyk221 on November 12, 2009, 12:50:51 pm
easier than unit 3
agreed, easier than unit 3.
Post by: Squida on November 12, 2009, 12:51:48 pm
Post by: kdgamz on November 12, 2009, 12:52:07 pm
easier than unit 3
it had to be easier than the midyear
Post by: THem on November 12, 2009, 12:53:15 pm
lol chem doesn't deserve a board
Coz chems super fkn boring
Post by: crappy on November 12, 2009, 12:57:32 pm
Post by: angelboykevin on November 12, 2009, 12:58:38 pm
lol chem doesn't deserve a board
Coz chems super fkn boring
lol totally agree!!!
Post by: lukeperry91 on November 12, 2009, 12:58:47 pm
Post by: herzy on November 12, 2009, 01:13:28 pm
anyone have a copy of the blank one, or of solutions?
Post by: Cheeseball on November 12, 2009, 01:17:30 pm
The one in brackets is question 10. I check with a friend who also wrote his answers on the data book and we had different answers for q10 but I can't remember what he had. The rest were the same
Post by: /0 on November 12, 2009, 01:18:42 pm
My multiple choice:
ADCADDABBBDCAAACABDD
Post by: johnbpj on November 12, 2009, 01:22:06 pm
1A, 2D, 3C, 4A, 5C, 6D, 7A, 8D, 9B, 10D, 11D, 12D, 13D, 14A, 15A, 16D, 17A, 18B, 19D, 20D
Post by: gil.fish on November 12, 2009, 01:22:58 pm
Post by: TheJosh on November 12, 2009, 01:26:49 pm
Does anyone have the exam solutions? 8-)
*Looks for TT and waits* 8-)
Post by: phuiii on November 12, 2009, 01:46:56 pm
Didn't manage to finish the battery question, but got everything else done.
OMG how good was the "unchanged" with the 6 boxes=6 marks OMG so easy.
And the production of the chemical.
Gah the Biofuel one kinda threw me off though
Post by: TheJosh on November 12, 2009, 01:48:00 pm
Post by: /0 on November 12, 2009, 01:50:12 pm
(equation is
Post by: mystikal on November 12, 2009, 01:51:01 pm
Post by: Over9000 on November 12, 2009, 01:52:40 pm
Wait, maybe thats an understatement.
Post by: Cheeseball on November 12, 2009, 01:53:29 pm
I just said sugar cane, which it essentially glucose anyway but I don't think an equation was necessary.
Post by: mystikal on November 12, 2009, 01:55:21 pm
Post by: TrueTears on November 12, 2009, 02:00:20 pm
LOL not for chem! I'm not confident with chem :(Does anyone have the exam solutions? 8-)
*Looks for TT and waits* 8-)
Post by: dylanru on November 12, 2009, 02:01:18 pm
I also said ethanol for my biofuel.same here
I just said sugar cane, which it essentially glucose anyway
Post by: TheJosh on November 12, 2009, 02:01:38 pm
LOL not for chem! I'm not confident with chem :(Does anyone have the exam solutions? 8-)
*Looks for TT and waits* 8-)
i guess youll only get 50 then...
Post by: TheJosh on November 12, 2009, 02:02:17 pm
Post by: dylanru on November 12, 2009, 02:03:56 pm
Post by: homghomg1 on November 12, 2009, 02:05:46 pm
That exam was much easier than I expected, considering the midyear was torture.I got lower, higher higher for first row
Didn't manage to finish the battery question, but got everything else done.
OMG how good was the "unchanged" with the 6 boxes=6 marks OMG so easy.
And the production of the chemical.
Gah the Biofuel one kinda threw me off though
and higher higher unchanged for second row
Post by: /0 on November 12, 2009, 02:06:13 pm
That exam was much easier than I expected, considering the midyear was torture.I got lower, higher higher for first row
Didn't manage to finish the battery question, but got everything else done.
OMG how good was the "unchanged" with the 6 boxes=6 marks OMG so easy.
And the production of the chemical.
Gah the Biofuel one kinda threw me off though
and higher higher unchanged for second row
high five!
Post by: rajah21 on November 12, 2009, 02:08:46 pm
+1 :DThat exam was much easier than I expected, considering the midyear was torture.I got lower, higher higher for first row
Didn't manage to finish the battery question, but got everything else done.
OMG how good was the "unchanged" with the 6 boxes=6 marks OMG so easy.
And the production of the chemical.
Gah the Biofuel one kinda threw me off though
and higher higher unchanged for second row
high five!
Post by: /0 on November 12, 2009, 02:10:50 pm
Post by: TrueTears on November 12, 2009, 02:11:49 pm
Did anyone get a copy of the exam? I tried to get one off the examiner but he was having none of itI tried, but the examiners for physics and chem are gay ass, won't let me get a copy ffs.
They were much nicer for spesh and methods.
Post by: Over9000 on November 12, 2009, 02:13:16 pm
Did anyone get a copy of the exam? I tried to get one off the examiner but he was having none of itHe sed get it from a chem teacher, didnt you go and get it?
Post by: /0 on November 12, 2009, 02:14:03 pm
Did anyone get a copy of the exam? I tried to get one off the examiner but he was having none of itHe sed get it from a chem teacher, didnt you go and get it?
nah couldn't find my chem teacher
Post by: homghomg1 on November 12, 2009, 02:14:51 pm
I think it was quite accessible and a LOT shorter than unit 3
My multiple choice:
ADCADDABBBDCAAACABDD
yeah i got the same as you :)
except for the last question OMG
easiest MC, the one about the electrolysis of lithium, i think i wrote down the wrong letter on my answer sheet by accident
either that, or i copied it onto my data booklet incorrectly
im hoping the latter...
Post by: Over9000 on November 12, 2009, 02:14:56 pm
That damn JJJJJJJJJJJJJDid anyone get a copy of the exam? I tried to get one off the examiner but he was having none of itHe sed get it from a chem teacher, didnt you go and get it?
nah couldn't find my chem teacher
Post by: tommyk221 on November 12, 2009, 02:17:54 pm
I think it was quite accessible and a LOT shorter than unit 3
My multiple choice:
ADCADDABBBDCAAACABDD
yeah i got the same as you :)
except for the last question OMG
easiest MC, the one about the electrolysis of lithium, i think i wrote down the wrong letter on my answer sheet by accident
either that, or i copied it onto my data booklet incorrectly
im hoping the latter...
Yeah same MC. Goooood :)
Post by: NE2000 on November 12, 2009, 02:22:00 pm
It was easier than midyears, but this stresses me out as silly mistakes count more. Took it pretty slow though to avoid them first time around.
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
Post by: avram_grant on November 12, 2009, 02:23:34 pm
Can anyone post the paper, if not the solutions?
It was easier than midyears, but this stresses me out as silly mistakes count more. Took it pretty slow though to avoid them first time around.
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
Yeh, i wrote the equation for it and said iron would be preferentially oxidise since lower e0 value
Post by: avram_grant on November 12, 2009, 02:24:28 pm
Post by: Cheeseball on November 12, 2009, 02:24:54 pm
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
I wrote the equation of Iron being oxidised with the E0 value to show it is a stronger reductant and hence will react in preference
Post by: avram_grant on November 12, 2009, 02:25:44 pm
Post by: homghomg1 on November 12, 2009, 02:26:42 pm
Can anyone post the paper, if not the solutions?hmm, it said iron as the B electrode if i recall correctly
It was easier than midyears, but this stresses me out as silly mistakes count more. Took it pretty slow though to avoid them first time around.
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
which means
So i wrote an overall reaction of iron reacting with
Post by: argentum on November 12, 2009, 02:27:18 pm
For some reason it has to be verified, so wont be a minute guys!
Post by: avram_grant on November 12, 2009, 02:28:06 pm
Can anyone post the paper, if not the solutions?hmm, it said iron as the B electrode if i recall correctly
It was easier than midyears, but this stresses me out as silly mistakes count more. Took it pretty slow though to avoid them first time around.
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
which means/
cell
So i wrote an overall reaction of iron reacting with
I think you had to combien iron with the VO2+ equation since VO2+ would be reduced
Post by: Ilovemathsmeth on November 12, 2009, 02:28:06 pm
Post by: /0 on November 12, 2009, 02:28:20 pm
If it said electrode B then .. shit i need the exam paper can't remember
Post by: homghomg1 on November 12, 2009, 02:28:24 pm
in which case you'd be correct
hope i didn't misread
Post by: simpak on November 12, 2009, 02:28:36 pm
Can anyone post the paper, if not the solutions?hmm, it said iron as the B electrode if i recall correctly
It was easier than midyears, but this stresses me out as silly mistakes count more. Took it pretty slow though to avoid them first time around.
For the one where it's like, write an overall equation to show why not to use iron, did ppl just write iron reacting with the
which means
So i wrote an overall reaction of iron reacting with
+1
Post by: rajah21 on November 12, 2009, 02:29:18 pm
what did you guys get for the last q?
From memory, something like 1.48 A? Not sure if that's correct, though.
Post by: TheJosh on November 12, 2009, 02:29:30 pm
what did you guys get for the last q?
1.4something Amps ^^ yeah 1.48A
Post by: argentum on November 12, 2009, 02:29:50 pm
Enjoy guys =D, I admit its a lil crappy though
Post by: methodsboy on November 12, 2009, 02:29:56 pm
Post by: methodsboy on November 12, 2009, 02:30:25 pm
got 1.47 A --> same thing anywaywhat did you guys get for the last q?
1.4something Amps ^^ yeah 1.48A
did anyone get 21.0kJ for the calorimeter?
Post by: dylanru on November 12, 2009, 02:30:38 pm
wait, i can't remember now, maybe it said electrode AIt said negative electrode or something like that
in which case you'd be correct
hope i didn't misread
[EDIT] - electrode B
Post by: tommyk221 on November 12, 2009, 02:34:23 pm
umm for the biofuel..I put biodesial. is that still correcT?
Yep
Post by: TheJosh on November 12, 2009, 02:34:41 pm
got 1.47 A --> same thing anywaywhat did you guys get for the last q?
1.4something Amps ^^ yeah 1.48A
did anyone get 21.0kJ for the calorimeter?
i did
Post by: homghomg1 on November 12, 2009, 02:35:55 pm
Post by: /0 on November 12, 2009, 02:36:04 pm
Post by: Ilovemathsmeth on November 12, 2009, 02:36:37 pm
Post by: methodsboy on November 12, 2009, 02:37:50 pm
I said biodiesel too! I'm not sure what the raw material is though :( Would methanol be incorrect?OMG I said methanol as well!!!!!!!!!!!!!
ur prob right since u go to MGGS
From unit 3 : biodesial : fatty acid + methanol yeah?
Post by: rajah21 on November 12, 2009, 02:38:09 pm
Post by: /0 on November 12, 2009, 02:38:38 pm
What was the reason for the reaction between H2 and Cu2+ not occuring?
The electrochemical series only predicts if reactions happen, it doesn't predict the rate at which they happen. It was probably a very slow reaction
Post by: methodsboy on November 12, 2009, 02:38:50 pm
What was the reason for the reaction between H2 and Cu2+ not occuring?i said conditions were diff to standard conditions
Post by: simpak on November 12, 2009, 02:39:04 pm
umm for the biofuel..I put biodesial. is that still correcT?
Yep
But, the one they gave you is a biodiesel.
I had biodiesel and then I changed it at the last minute because the thing they gave you was oneeeeeee.
So unsure if it'll be accepted.
Post by: simpak on November 12, 2009, 02:39:42 pm
What was the reason for the reaction between H2 and Cu2+ not occuring?i said conditions were diff to standard conditions
I said reaction rate occurred too slowly for it to be observed.
It's either what is above, that, or the activation energy was not met.
Those were your options.
Post by: NE2000 on November 12, 2009, 02:41:38 pm
I think biodiesel would be ok, they said other than methyl palmitate, they didn't want you to just write methyl palmitate, although I should've thought about that before writing it. omg fail.
Post by: simpak on November 12, 2009, 02:42:59 pm
Argh...yeah electrode B. The way I was thinking was that iron would react instead of V2+ or whatever so I gave the equation of it reacting preferentially. Didn't think about the fact that the real problem is it reacts with something in the compartment itself! omg silly errors
I think biodiesel would be ok, they said other than methyl palmitate, they didn't want you to just write methyl palmitate, although I should've thought about that before writing it. omg fail.
Yeah I think that this is true, because I think a lot of people would have chosen biodiesel.
But the reason I realised, was that I thought maybe, they wanted me to use a specific chemical.
So I went to the data book to find a raw material fatty acid.
And I was like "OMG THAT'S THE ONE THEY'VE GIVEN US, CHANGE TO ETHANOL NOW!"
Post by: TrueTears on November 12, 2009, 02:43:51 pm
Post by: NE2000 on November 12, 2009, 02:44:42 pm
Argh...yeah electrode B. The way I was thinking was that iron would react instead of V2+ or whatever so I gave the equation of it reacting preferentially. Didn't think about the fact that the real problem is it reacts with something in the compartment itself! omg silly errors
I think biodiesel would be ok, they said other than methyl palmitate, they didn't want you to just write methyl palmitate, although I should've thought about that before writing it. omg fail.
Yeah I think that this is true, because I think a lot of people would have chosen biodiesel.
But the reason I realised, was that I thought maybe, they wanted me to use a specific chemical.
So I went to the data book to find a raw material fatty acid.
And I was like "OMG THAT'S THE ONE THEY'VE GIVEN US, CHANGE TO ETHANOL NOW!"
Anyway the thing about using up food stocks still applies (as they get the fatty acids off plant materials)
Post by: /0 on November 12, 2009, 02:44:49 pm
Cool exam.
(http://s3-llnw-screenshots.wegame.com/5-0663891325055718/0663891325055718_l.png)
Post by: NE2000 on November 12, 2009, 02:45:37 pm
Post by: homghomg1 on November 12, 2009, 02:46:54 pm
Q2) c) iii) mass of NH4NO3 = 3.6 g
Q3) c) ii) 0.815 mol of dimethyl blah blah iii) 1.97 mol of methanol originally
Q4) a) 3.39 kJ/C b) 21.0 kJ c) energy released is 1.07 * 10^4 kJ/mol of methyl palmitate d) - 2.14 * 10^4 kJ/mol (of reaction)
Post by: /0 on November 12, 2009, 02:48:22 pm
some of my answers which i wrote down:
Q2) c) iii) mass of NH4NO3 = 3.6 g
Q3) c) ii) 0.815 mol of dimethyl blah blah iii) 1.97 mol of methanol originally
Q4) a) 3.39 kJ/C b) 21.0 kJ c) energy released is 1.07 * 10^4 kJ/mol of methyl palmitate d) - 2.14 * 10^4 kJ/mol (of reaction)
agreed except perhaps you meant 0.815M methanol in q3 c) :P
Post by: NE2000 on November 12, 2009, 02:50:01 pm
some of my answers which i wrote down:
Q2) c) iii) mass of NH4NO3 = 3.6 g
Q3) c) ii) 0.815 mol of dimethyl blah blah iii) 1.97 mol of methanol originally
Q4) a) 3.39 kJ/C b) 21.0 kJ c) energy released is 1.07 * 10^4 kJ/mol of methyl palmitate d) - 2.14 * 10^4 kJ/mol (of reaction)
agreed except perhaps you meant 0.815M methanol in q3 c) :P
Agreed with those as well
Post by: NE2000 on November 12, 2009, 02:54:21 pm
for the way in which they differ I think I put something about fuel cells generally not made to electrolyze the reactants ala a secondary galvanic cells. Continuous flow of reactants was an option but something about the pump turned me away from that.
Recycle the heat energy to reaction 1
And the oxidation reaction was that of water going to O2, 4H+ etc?
Post by: TrueTears on November 12, 2009, 02:55:00 pm
Post by: NE2000 on November 12, 2009, 02:55:55 pm
Funny I can't remember anything from that exam =S
I couldn't until I saw the exam again lol. I think I went into relax mode a couple of hours too early, creating my own problems with silly mistakes
Post by: TheJosh on November 12, 2009, 02:56:50 pm
for the way in which they differ I think I put something about fuel cells generally not made to electrolyze the reactants ala a secondary galvanic cells. Continuous flow of reactants was an option but something about the pump turned me away from that.
i said you cant recharge fuel cells they just require continuous supply of reactant in order to maintain electricity production
Post by: Ilovemathsmeth on November 12, 2009, 03:06:10 pm
Post by: ScyLLa on November 12, 2009, 03:10:43 pm
I also said ethanol for my biofuel.
I just said sugar cane, which it essentially glucose anyway but I don't think an equation was necessary.
OMFG..... i cant believe it. i put that answer thinking why i even bother doing chem. LOL
it was honestly the most random thing that came to my head.
Post by: TheJosh on November 12, 2009, 03:12:15 pm
I also said ethanol for my biofuel.
I just said sugar cane, which it essentially glucose anyway but I don't think an equation was necessary.
OMFG..... i cant believe it. i put that answer thinking why i even bother doing chem. LOL
it was honestly the most random thing that came to my head.
The Chem gods bestowed their knowledge unto you :angel:
Post by: btuned on November 12, 2009, 03:14:59 pm
some of my answers which i wrote down:Same here! I was thinking the values of H were too alrge to be a combustion of a biodiesel. But then again.. it's an exam after all, bullshit values might sometimes be the right one
Q2) c) iii) mass of NH4NO3 = 3.6 g
Q3) c) ii) 0.815 mol of dimethyl blah blah iii) 1.97 mol of methanol originally
Q4) a) 3.39 kJ/C b) 21.0 kJ c) energy released is 1.07 * 10^4 kJ/mol of methyl palmitate d) - 2.14 * 10^4 kJ/mol (of reaction)
Post by: /0 on November 12, 2009, 03:20:14 pm
Post by: ron09 on November 12, 2009, 03:21:10 pm
for short answer... i got these
1)a H202 + 2Ag+ -> O2 + 2H+ + 2Ag (I used Ag as an example to make and overall eqn to demonstrate H2O2 acting as reductant)
1)b I wasn't sure..i said no electrodes so Cu can't form solid.. not sure though.
2)a ii Start at 60, go up to 120 and then down to 85
2)b i NH4+ + H20 <-/-> NH3 + H3O+
2)b ii Diluted, Fwd reaction is favoured
2)b iii Equal to
2)c i Ka= ([NH3][H3O+])/([NH4+])
2)c ii 9.12x10^-6 M
2)c iii 3.56g
3)a K=([H2O][CH3OCH3])/([CH3OH]^2)
3)b K=0.174
3)c i 0.017 mol/L
3)c ii 0.815 mol
3)c iii 1.969 mol
4)a CF=3385 J/C
4)b 20.955kJ
4)c 10695KJ
4)d H=-21390 kJ/mol
4)e I chose ethanol from the anaerobic decomposition of biomass; disadvantage is that it produces CO2 (greenhouse gas)
4)f High efficiency; Harmful nuclear waste produced
5)a A=+ B=-
5)b VO2
5)c VO + H2O + V -> VO2 + 2H + V
5)d Fuel cells typically have electrodes that act as catalysts; this cell doesn't.
5)e Iron is oxidised preferentially over vanadium.
6)a LHH, UHU
6)b Heat can be used to drive reaction 1 (its endothermic)
6)c Chose Sulfuric Acid; i Reuse excess H2SO4 to create Oleum (not sure whether this will suffice! but couldn't think of anything else) ii Corrosive; iii Dehydrating agent and used in production of fertilizers (super phosphate).
7)a SO4^2- -> SO4 + 2e- (not sure)
7)b 1.48A
Not fully sure on the correctness of everything..but I found the exam fairly straightfwd.
Post by: homghomg1 on November 12, 2009, 03:30:37 pm
for MC i got 1)ACCADDABBB 11)DCAAACABBD
for short answer... i got these
1)a H202 + 2Ag+ -> O2 + 2H+ + 2Ag (I used Ag as an example to make and overall eqn to demonstrate H2O2 acting as reductant)
1)b I wasn't sure..i said no electrodes so Cu can't form solid.. not sure though.
2)a ii Start at 60, go up to 120 and then down to 85
2)b i NH4+ + H20 <-/-> NH3 + H3O+
2)b ii Diluted, Fwd reaction is favoured
2)b iii Equal to
2)c i Ka= ([NH3][H3O+])/([NH4+])
2)c ii 9.12x10^-6 M
2)c iii 3.56g
3)a K=([H2O][CH3OCH3])/([CH3OH]^2)
3)b K=0.174
3)c i 0.017 mol/L
3)c ii 0.815 mol
3)c iii 1.969 mol
4)a CF=3385 J/C
4)b 20.955kJ
4)c 10695KJ
4)d H=-21390 kJ/mol
4)e I chose ethanol from the anaerobic decomposition of biomass; disadvantage is that it produces CO2 (greenhouse gas)
4)f High efficiency; Harmful nuclear waste produced
5)a A=+ B=-
5)b VO2
5)c VO + H2O + V -> VO2 + 2H + V
5)d Fuel cells typically have electrodes that act as catalysts; this cell doesn't.
5)e Iron is oxidised preferentially over vanadium.
6)a LHH, UHU
6)b Heat can be used to drive reaction 1 (its endothermic)
6)c Chose Sulfuric Acid; i Reuse excess H2SO4 to create Oleum (not sure whether this will suffice! but couldn't think of anything else) ii Corrosive; iii Dehydrating agent and used in production of fertilizers (super phosphate).
7)a SO4^2- -> SO4 + 2e- (not sure)
7)b 1.48A
Not fully sure on the correctness of everything..but I found the exam fairly straightfwd.
2 b) ii) was removal of products. if it was dilution, the rate of backward and foward reaction would have suddenly dropped for both. this was only seen for backwards rate though, which indicates products have been removed (lower concentration of products = less collisions = lower backwards rate)
since there are now less products, there is a net reaction foward, and over time the rate of reaction foward GRADUALLY decreases, while the backwards rate GRADUALLY increases, as is demonstrated by the graph
for 5) d) i said that fuel cells usually have gaseous reactants, but in this cell the reactants are ions in an aqueous solution
for 1) b) i said conditions may not have been standard (25 degrees and 1.0 M concentration of Cu2+), as is required for predictions made by electrochemical series to be correct
but i think the safer answer is to say the electrochemical series does not predict rate of reaction; hence there may have been a very slow rate
Post by: Cheeseball on November 12, 2009, 03:30:51 pm
for MC i got 1)ADCADDABBB 11)DCAAACABDD
for short answer... i got these
1)a H202 + 2Ag+ -> O2 + 2H+ + 2Ag (I used Ag as an example to make and overall eqn to demonstrate H2O2 acting as reductant)
1)b Rate is too slow
2)a ii Start at 60, go up to 120 and then down to 85
2)b i NH4+ + H20 <-/-> NH3 + H3O+
2)b ii Removal of products
2)b iii Equal to
2)c i Ka= ([NH3][H3O+])/([NH4+])
2)c ii 9.12x10^-6 M
2)c iii 3.56g
3)a K=([H2O][CH3OCH3])/([CH3OH]^2)
3)b K=0.174
3)c i 0.017 mol/L
3)c ii 0.815 mol
3)c iii 1.969 mol
4)a CF=3385 J/C
4)b 20.955kJ
4)c 10695KJ
4)d H=-21390 kJ/mol
4)e I chose ethanol from the anaerobic decomposition of biomass; disadvantage is that it produces CO2 (greenhouse gas)
4)f High efficiency; Harmful nuclear waste produced
5)a A=+ B=-
5)b VO2
5)c VO + H2O + V -> VO2 + 2H + V
5)d Fuel cells typically have electrodes that act as catalysts; this cell doesn't.
5)e Iron is oxidised preferentially over vanadium.
6)a LHH, HHU
6)b Heat can be used to drive reaction 1 (its endothermic)
6)c Chose Sulfuric Acid; reuse unreacted reactants (its equilibrium so there will be some) ii Corrosive; iii Dehydrating agent and used in production of fertilizers (super phosphate).
7)a some h2o reaction (not sure)
7)b 1.48A
Not fully sure on the correctness of everything..but I found the exam fairly straightfwd.
bolded text are changes
Post by: Ilovemathsmeth on November 12, 2009, 03:39:03 pm
Post by: ron09 on November 12, 2009, 03:40:36 pm
7)a was tricky..didnt think of water; 6)c again didn't think of it! lol; 2b ii Another oversight
with around 8 marks in total gone.. is it still possible for an A+?
Post by: /0 on November 12, 2009, 03:42:27 pm
For that 'removal of products' one, could you have said addition of products?
the forward and backward rates of the second equilibrium are lower than the first, so there must be less collisions and hence less particles overall :/
Post by: simpak on November 12, 2009, 03:46:00 pm
I think I lost an answer mark because my calc is shit, and for the Electrode B question (because I don't have time to download the pdf rn...)
Did it ask you to EXPLAIN why Fe couldn't be used as well as the half eq? Because if so I missed that bit, crap.
Post by: d0minicz on November 12, 2009, 03:47:00 pm
Thanks :) I feel good now that I didn't get that many wrong! lol
7)a was tricky..didnt think of water; 6)c again didn't think of it! lol; 2b ii Another oversight
with around 8 marks in total gone.. is it still possible for an A+?
i believe so
Post by: /0 on November 12, 2009, 03:47:35 pm
Yeah it's not addition of products.
I think I lost an answer mark because my calc is shit, and for the Electrode B question (because I don't have time to download the pdf rn...)
Did it ask you to EXPLAIN why Fe couldn't be used as well as the half eq? Because if so I missed that bit, crap.
nope, 1 mark 1 equation :)
Post by: homghomg1 on November 12, 2009, 03:48:54 pm
Yeah it's not addition of products.It's a 1 mark question and it asks to write an equation which shows why iron isn't suitable, so you didn't have to explain in words i think
I think I lost an answer mark because my calc is shit, and for the Electrode B question (because I don't have time to download the pdf rn...)
Did it ask you to EXPLAIN why Fe couldn't be used as well as the half eq? Because if so I missed that bit, crap.
i wrote a short sentence just in case
Post by: ron09 on November 12, 2009, 03:49:20 pm
Post by: Cheeseball on November 12, 2009, 03:49:56 pm
It's only worth one mark and I got it wrong :( I wrote the iron oxidation half equation
Post by: kendraaaaa on November 12, 2009, 03:52:29 pm
Any else found that the MC took them longer than 20 minutes? Took me like 25 to almost 30. I got kind of panicky then! Haha
Post by: tommyk221 on November 12, 2009, 03:56:39 pm
So happy. Everything is looking good but I know I stuffed up the 'calculate the mass of NH3OH" or whatever question, I got like 0.0035 or something. But apart from that it's all good.
Any else found that the MC took them longer than 20 minutes? Took me like 25 to almost 30. I got kind of panicky then! Haha
Haha same I got something really small as well. Oh well.
And yeah MC took me a while, about 25 mins.
Post by: IntoTheNewWorld on November 12, 2009, 04:01:15 pm
So happy. Everything is looking good but I know I stuffed up the 'calculate the mass of NH3OH" or whatever question, I got like 0.0035 or something. But apart from that it's all good.
Any else found that the MC took them longer than 20 minutes? Took me like 25 to almost 30. I got kind of panicky then! Haha
Haha same I got something really small as well. Oh well.
And yeah MC took me a while, about 25 mins.
took me a while too, but I did short answer first.
Post by: Dark Horse on November 12, 2009, 04:01:32 pm
Post by: homghomg1 on November 12, 2009, 04:05:43 pm
For the question what will have the highest concnetration at the anode after recharge, wouldnt it be V2+? Please tell me it is :(yeah some people at my school got V2+
i thought it was veryyyy ambiguous
anode changes depending on whether it's discharging or recharging!
but in the end, it comes down to the fact that they say fully charged in bold
this means it can't be any more charged, and the only possibility is for discharge to occur, in which case electrode B is the anode, and V2+ is highest concentration
Post by: simpak on November 12, 2009, 04:07:44 pm
Thanks guys, that makes me feel better! In that case, should have only lost about two or three marks on long answer.
Still need to check MC.
Post by: /0 on November 12, 2009, 04:08:49 pm
If we arrange the equations so that the cell is recharging, isn't the anode electrode A?
Post by: simpak on November 12, 2009, 04:11:50 pm
I put VO with a charge of 2+
The second one.
Post by: /0 on November 12, 2009, 04:13:49 pm
Wait what do we think it is?
I put VO with a charge of 2+
The second one.
The question is equivalent to "As the cell recharges, which species eventually has the greatest concentration at the anode?"
If we arrange the equations so that the cell is recharging, isn't the anode electrode A?
If the anode is electrode A when the cell is recharging then the equation is
And from this I got
Post by: kev0 on November 12, 2009, 04:15:04 pm
Quote
2)a ii Start at 60, go up to 120 and then down to 85
Do you mean.
Start at 60, Go to 70 then down to 35?
Post by: kendraaaaa on November 12, 2009, 04:15:53 pm
Not sure though
Post by: Cheeseball on November 12, 2009, 04:16:10 pm
Quote2)a ii Start at 60, go up to 120 and then down to 85
Do you mean.
Start at 60, Go to 70 then down to 35?
It was endothermic
Post by: kendraaaaa on November 12, 2009, 04:17:16 pm
Quote2)a ii Start at 60, go up to 120 and then down to 85
Do you mean.
Start at 60, Go to 70 then down to 35?
It was endothermic
+1, OP is right.
Post by: /0 on November 12, 2009, 04:18:15 pm
Are you sure fully charged is the same as "as the cell recharges", I think this is a bit vague. Because it says in the question "when the cell is fully charged" which I interpreted that the reactant at the anode will have a higher concentration than the product. Which would be V2+
Not sure though
Ah I see what you mean... yes that is very ambiguous. Either equation could occur at the anode depending on whether it is charging or not.
Do you think they'll scrap the question?
Post by: roberem on November 12, 2009, 04:18:58 pm
What would be a HAZCHEM symbol for sulfuric acid?corrosive :)
Post by: /0 on November 12, 2009, 04:19:22 pm
What would be a HAZCHEM symbol for sulfuric acid?corrosive :)
cooool
Post by: homghomg1 on November 12, 2009, 04:19:40 pm
The question is equivalent to "As the cell recharges, which species eventually has the greatest concentration at the anode?"yeah that's where the ambiguity comes in
If we arrange the equations so that the cell is recharging, isn't the anode electrode A?
could be interpreted as the anode when the cell has JUST finished recharging, or could be interpreted as the anode when the cell is discharging, since it is fully charged and can't recharge any further
Post by: rajah21 on November 12, 2009, 04:21:14 pm
Post by: kendraaaaa on November 12, 2009, 04:23:57 pm
For 2)c iii (the mass of NH4NO3), how did you get 3.56g? I think I got something way smaller but I'm not sure how :S
I was confused with this question.
I found the concentration of NH4+ ions by using the pH value to find [H+] and used the Ka value from the booklet. Then I found the mole of NH4. Then to get the mass, do you use the molar value of NH4 or NH4NO3. Is my working correct though? Haha blargh
Post by: PepsiMax on November 12, 2009, 04:24:19 pm
According to my chem textbook -coooolWhat would be a HAZCHEM symbol for sulfuric acid?corrosive :)
Toxic
Corrosive
Oxidising
I chose oxidising because I remembered that sulfuric acid is a strong oxidising agent.
Post by: rajah21 on November 12, 2009, 04:25:47 pm
For 2)c iii (the mass of NH4NO3), how did you get 3.56g? I think I got something way smaller but I'm not sure how :S
I was confused with this question.
I found the concentration of NH4+ ions by using the pH value to find [H+] and used the Ka value from the booklet. Then I found the mole of NH4. Then to get the mass, do you use the molar value of NH4 or NH4NO3. Is my working correct though? Haha blargh
Ah crap. I think I found the mass of NH4+ because I used the same method as you but I didn't find the n(NH4NO3) in order to find the mass. Damn!
Post by: Cheeseball on November 12, 2009, 04:29:34 pm
According to my chem textbook -coooolWhat would be a HAZCHEM symbol for sulfuric acid?corrosive :)
Toxic
Corrosive
Oxidising
I chose oxidising because I remembered that sulfuric acid is a strong oxidising agent.
I chose oxidising and straight after the exam I was thinking I should've picked corrosive because it's the safe answer
Post by: btuned on November 12, 2009, 04:37:24 pm
Post by: gallinari on November 12, 2009, 04:41:16 pm
:S
Post by: Sardi on November 12, 2009, 04:41:44 pm
Post by: kendraaaaa on November 12, 2009, 04:43:52 pm
do we have a majority on the mulitple choice answers yet?
I used /0's answers which were on page one. I got 17/20 according to that, and the ones I got wrong were the ones I thought I would. So yeah, they seem pretty reliable.
For the question saying why won't Cu2+ react with H2, do you reckon it was valid to write: because the 2H+ can also react with the SO42- in an acid base reaction, thus decreasing the amount of H2 available for redox reaction with Cu2+??
:S
I think the safest answer would be to to say that the reaction rate may have been very slow hence no observations could be made.
Post by: Sardi on November 12, 2009, 04:46:06 pm
This board is like, 9 pages!!
Post by: Cheeseball on November 12, 2009, 04:49:01 pm
For the question saying why won't Cu2+ react with H2, do you reckon it was valid to write: because the 2H+ can also react with the SO42- in an acid base reaction, thus decreasing the amount of H2 available for redox reaction with Cu2+??
:S
Where the hell is the 2H+ coming from?
Post by: rajah21 on November 12, 2009, 04:49:08 pm
I think it was quite accessible and a LOT shorter than unit 3
My multiple choice:
ADCADDABBBDCAAACABDD
Post by: homghomg1 on November 12, 2009, 04:52:37 pm
Post by: PepsiMax on November 12, 2009, 04:54:12 pm
i know this is annoying :D, but does anyone have any indication of what a+ sacs in a good cohort, 67/73 and 73/76 for exam 1 and 2 is capable of gettinghttp://vcenotes.com/forum/index.php/topic,6688.0.html
Post by: btuned on November 12, 2009, 04:54:21 pm
i know this is annoying :D, but does anyone have any indication of what a+ sacs in a good cohort, 67/73 and 73/76 for exam 1 and 2 is capable of getting46? Lmao
Post by: Dark Horse on November 12, 2009, 04:54:45 pm
Post by: PepsiMax on November 12, 2009, 04:54:52 pm
Post by: Cheeseball on November 12, 2009, 04:57:58 pm
i know this is annoying :D, but does anyone have any indication of what a+ sacs in a good cohort, 67/73 and 73/76 for exam 1 and 2 is capable of getting46? Lmao
It's basing it off last years scores though. Remember this years midyear exam was a killer
Post by: tommyk221 on November 12, 2009, 05:02:36 pm
For 2)c iii (the mass of NH4NO3), how did you get 3.56g? I think I got something way smaller but I'm not sure how :S
I got a smaller answer as well. I have no idea where I went wrong. But I certainly did go wrong haha
Post by: bloodboy on November 12, 2009, 05:03:05 pm
Post by: tommyk221 on November 12, 2009, 05:04:56 pm
ADCADDABBBDCAAACABDD
Post by: rhjc.1991 on November 12, 2009, 05:09:35 pm
Post by: NE2000 on November 12, 2009, 05:10:35 pm
EDIT: MAKE SOME ROOM PEOPLE COZ I'M PART OF THE FURNITURE!!!!!!!!!!!!!!!!!!!!!
Post by: StringFever on November 12, 2009, 05:13:12 pm
Wondering what people said the "raw material" was for Biogas if you put that down as your response in the exam? :)
Post by: NE2000 on November 12, 2009, 05:15:05 pm
Post by: kendraaaaa on November 12, 2009, 05:15:17 pm
is the 1.0M solution of Cabr2 mean that br is twice as concentrated?
Don't think so. It just means that two Br- ions are required, but the concentration is still 1.0M which is standard conditions.
Post by: kev0 on November 12, 2009, 05:22:29 pm
Quote2)a ii Start at 60, go up to 120 and then down to 85
Do you mean.
Start at 60, Go to 70 then down to 35?
It was endothermic
+1, OP is right.
Oh my bad.
The PDF scans were kinda rough on the sign. I completely forgotten about the question :I
Post by: Hooligan on November 12, 2009, 05:35:39 pm
I said biodiesel too! I'm not sure what the raw material is though :( Would methanol be incorrect?OMG I said methanol as well!!!!!!!!!!!!!
ur prob right since u go to MGGS
From unit 3 : biodesial : fatty acid + methanol yeah?
Yes, however, the raw material for Biodiesal is vegetable oil. Not sure if you would be mark wrong though. :P
Post by: NE2000 on November 12, 2009, 05:38:43 pm
Post by: avram_grant on November 12, 2009, 05:59:27 pm
Post by: Dark Horse on November 12, 2009, 06:46:20 pm
Post by: Potter on November 12, 2009, 06:50:33 pm
is the 1.0M solution of Cabr2 mean that br is twice as concentrated?
Don't think so. It just means that two Br- ions are required, but the concentration is still 1.0M which is standard conditions.
I'd say it means there is 1 mol of Ca2+ ions and 2 mol of Br- ions.
Reason being.. If you have an ionic substance and dissolve it in water it breaks into it's cation/anion.
Since the ratio is 1:2. 2 mol of Br- will be in the solution.
Post by: furtheyboy on November 12, 2009, 06:52:30 pm
Shouldnt the answer be B. If you have a carbon electrode, then H2O would be oxidised, which would in turn produce O2, this would result in a big reaction with the Lithium metal?
Have I got this wrong?
Post by: Potter on November 12, 2009, 06:59:18 pm
for MC Q20:
Shouldnt the answer be B. If you have a carbon electrode, then H2O would be oxidised, which would in turn produce O2, this would result in a big reaction with the Lithium metal?
Have I got this wrong?
From my understanding, C electrodes are used cause they're chemically inert. Just like Pt but a cheaper alternative.
Also, if you chose B there's no H2O in the cell. Just molten LiCl
Post by: Hissy88 on November 12, 2009, 07:08:56 pm
Quote2)a ii Start at 60, go up to 120 and then down to 85
Do you mean.
Start at 60, Go to 70 then down to 35?
It was endothermic
+1, OP is right.
Oh my bad.
The PDF scans were kinda rough on the sign. I completely forgotten about the question :I
It doesn't go down because that means the enthalpy is -ve so energy is released, when it is really absorbed
Post by: kashmuq on November 12, 2009, 07:48:49 pm
Post by: kendraaaaa on November 12, 2009, 08:16:06 pm
is the 1.0M solution of Cabr2 mean that br is twice as concentrated?
Don't think so. It just means that two Br- ions are required, but the concentration is still 1.0M which is standard conditions.
I'd say it means there is 1 mol of Ca2+ ions and 2 mol of Br- ions.
Reason being.. If you have an ionic substance and dissolve it in water it breaks into it's cation/anion.
Since the ratio is 1:2. 2 mol of Br- will be in the solution.
That's irrelevant in this context I think, the option was simply to test whether or not you know that 1.0M was one of the standard conditions.
Post by: NE2000 on November 12, 2009, 08:38:15 pm
for MC Q20:
Shouldnt the answer be B. If you have a carbon electrode, then H2O would be oxidised, which would in turn produce O2, this would result in a big reaction with the Lithium metal?
Have I got this wrong?
Molten LiCl so no water. If you used iron, then that would be oxidized at the anode. And if allowed the Fe2+ would travel across to the cathode and be preferentially reduced. This results in electrolytic cell fail.
Post by: methodsboy on November 12, 2009, 08:42:28 pm
Post by: NE2000 on November 12, 2009, 08:43:56 pm
Post by: kendraaaaa on November 12, 2009, 08:46:39 pm
^^ so the correct answer was D?
Yah I put D. Because firstly you needed a molten electrolyte, and secondly you couldn't use iron as the electrode because a) it's more expensive than carbon and b) the products of electrolysis would undergo a vigorous spontaneous reduction as lithium is an extremely powerful reductant.
Post by: methodsboy on November 12, 2009, 08:47:04 pm
ok question 12. I spent two minutes on this cause i had a sudden mental blank.
postive to positive?
negative to negative?
(at first i though it was - to + and + to -; but then i thought that the power supply determines the electrode charge)
Post by: kendraaaaa on November 12, 2009, 08:47:57 pm
kewl.
ok question 12. I spent two minutes on this cause i had a sudden mental blank.
postive to positive?
negative to negative?
(at first i though it was - to + and + to -; but then i thought that the power supply determines the electrode charge)
Cathode's connected to the postive terminal of the powerpack. Forgot which letters were which.
Post by: NE2000 on November 12, 2009, 08:49:03 pm
Post by: methodsboy on November 12, 2009, 08:53:09 pm
A to C. B to D. Positive to positive. Negative to negative.OMG i got it right! i thought it was wrong when i walked out of the room. Wait, ur not joking right?
Post by: tripz on November 12, 2009, 08:54:00 pm
What would be a HAZCHEM symbol for sulfuric acid?corrosive :)
cooool
Oh my goodness O.O Did I even do that question?!!?1
Post by: NE2000 on November 12, 2009, 08:55:14 pm
A to C. B to D. Positive to positive. Negative to negative.OMG i got it right! i thought it was wrong when i walked out of the room. Wait, ur not joking right?
The positive and negative electrodes remain exactly the same. It's just that their roles change. Think about it, during discharge at the negative electrode (anode), oxidation occurs. You need reduction to occur during charging. Where does that occur? At the negative electrode.
Post by: simpak on November 12, 2009, 09:06:46 pm
Post by: Cheeseball on November 12, 2009, 09:08:25 pm
GUISE, WHAT HAVE WE DECIDED FOR THE AMBIGUOUS CATHODE ANODE QUESTION WITH THE VO SPECIES ETC?
That is it ambiguous lol. VCAA will end up giving both answers as correct
Post by: angelboykevin on November 12, 2009, 09:18:10 pm
Post by: Cheeseball on November 12, 2009, 09:27:54 pm
Post by: phuiii on November 12, 2009, 10:46:08 pm
Godly solutions on the way if Mao does rofl
Post by: /0 on November 13, 2009, 01:34:05 pm
Oh well, I don't fully agree, but what can you do about it?
Post by: kendraaaaa on November 13, 2009, 02:39:33 pm
I emailed my chem teacher (who is an assessor), he said fully charged means it's about to discharge.
Oh well, I don't fully agree, but what can you do about it?
They'll make both of them right solutions, the question was way to ambiguous and I was lucky that I interpreted as it being 'about to discharge'.
Post by: TheJosh on November 13, 2009, 02:44:11 pm
Post by: kendraaaaa on November 13, 2009, 04:16:05 pm
where are the answers?
First or second page of this thread. They're not 'set' answers just suggested solutions, so don't take them as gospel.
Post by: tomygun_123 on November 13, 2009, 09:43:57 pm
i reckon that the exam was surprisingly easy compared to mid year and last year. thought the questions were of good quality and would have tested people. I'm aiming for a A+, so hope i get it. these are my multichoice answers, let me know if you agree or disagree.
1A, 2D, 3C, 4A, 5C, 6D, 7A, 8D, 9B, 10D, 11D, 12D, 13D, 14A, 15A, 16D, 17A, 18B, 19D, 20D
Wow A+... i wish i could get one too, can you teach me how, faggot.
Post by: sir0004 on November 13, 2009, 10:59:30 pm
Post by: simpak on November 13, 2009, 11:39:46 pm
Post by: kendraaaaa on November 13, 2009, 11:45:05 pm
13 I got A. What question was that again?
A for me too.
Post by: NE2000 on November 14, 2009, 07:47:48 am
I emailed my chem teacher (who is an assessor), he said fully charged means it's about to discharge.
Oh well, I don't fully agree, but what can you do about it?
Is this his view or what the markers are marking?
I hope they give both.
Post by: simpak on November 14, 2009, 08:33:08 am
13 I got A. What question was that again?
A for me too.
I looked it up, it's the one about the pipes.
It can't be the reduction of oxygen and water to OH guys.
Look where region X is.
It's surrounded by the water droplet; no oxygen gets through, there are only water molecules.
So it has to be the anode, because if it were the cathode, reduction would occur and it would corrode.
Only iron can react because no O2 is present to react.
The answer is A.
Post by: coonoo on November 14, 2009, 09:10:49 am
Post by: shonira on November 14, 2009, 09:21:42 am
For question 12, was the answer C or D? Its the question about the arrangement of a cell recharging. C is a A connected to C (both positive)and B connected to D (both negative). D is A to D and B to C.
i think the answer was C (positive-positive and negative-negative)....thats what i found from my chem textbook.....i stuffed up that question cos i initially wrote C then changed it to D at the last minute cos i was doubting myself. GRRR :I
Post by: simpak on November 14, 2009, 09:24:07 am
The picture of the positive and negative one was the cell discharging, when the anode is negative and the cathode is positive.
Recharging is equivalent to electrolysis, therefore you have to switch them so that the anode is positive and the cathode is negative.
D.
Post by: silva on November 14, 2009, 10:22:57 am
N...it's D.ohhhhhhhhhhh you serious? thank fuck i picked D then, what you're saying sounds like the proper reasoning unless someone who picked C (negative-negative, positive-positive) could post their reasoning
The picture of the positive and negative one was the cell discharging, when the anode is negative and the cathode is positive.
Recharging is equivalent to electrolysis, therefore you have to switch them so that the anode is positive and the cathode is negative.
D.
Post by: shonira on November 14, 2009, 10:25:02 am
N...it's D.ohhhhhhhhhhh you serious? thank fuck i picked D then, what you're saying sounds like the proper reasoning unless someone who picked C (negative-negative, positive-positive) could post their reasoning
The picture of the positive and negative one was the cell discharging, when the anode is negative and the cathode is positive.
Recharging is equivalent to electrolysis, therefore you have to switch them so that the anode is positive and the cathode is negative.
D.
omg yea i understand now....thank god i changed it to D
Post by: furtheyboy on November 14, 2009, 10:27:22 am
--Originally you will be having reduction occuring at the positive electrode.
--Therefore, when recharging you want those ions that have been reduced to be oxidised at the anode.
--Now, when recharging the anode is positively charged and we know that the external energy source is the decider of the polarities.
--Hence, you must attach the positive from the external source to the battery as to keep that electrode positively charged and for oxidation to occur, resulting in the corrosion of the products.
Post by: simpak on November 14, 2009, 12:02:04 pm
For C:
--Originally you will be having reduction occuring at the positive electrode.
--Therefore, when recharging you want those ions that have been reduced to be oxidised at the anode.
--Now, when recharging the anode is positively charged and we know that the external energy source is the decider of the polarities.
--Hence, you must attach the positive from the external source to the battery as to keep that electrode positively charged and for oxidation to occur, resulting in the corrosion of the products.
Yeah on second thought that does sound relatively correct...
Wait...
Let me think for a second...
But.
Nup that's right! SORRY GUYS, LISTEN TO THIS PERSON NOT ME.
Post by: forsaken231 on November 14, 2009, 12:12:22 pm
Post by: kendraaaaa on November 14, 2009, 12:33:12 pm
yeah it's C.. although i still think 13 is A
It is dude
Post by: NE2000 on November 14, 2009, 01:22:39 pm
13 I got A. What question was that again?
A for me too.
I looked it up, it's the one about the pipes.
It can't be the reduction of oxygen and water to OH guys.
Look where region X is.
It's surrounded by the water droplet; no oxygen gets through, there are only water molecules.
So it has to be the anode, because if it were the cathode, reduction would occur and it would corrode.
Only iron can react because no O2 is present to react.
The answer is A.
agree with this. That was my logic in the exam :)
Post by: elbitar on November 14, 2009, 03:54:28 pm
Post by: simpak on November 14, 2009, 06:45:29 pm
Despite me being inept at the other question TRUST ME ON THIS ONE.
REGION X HAD NO AIR, NO O2.
Post by: PepsiMax on November 14, 2009, 07:47:49 pm
I also had C for 12 as well (positive - positive, negative-negative).
Post by: Ghost on November 15, 2009, 12:08:39 pm
13 I got A. What question was that again?
A for me too.
I looked it up, it's the one about the pipes.
It can't be the reduction of oxygen and water to OH guys.
Look where region X is.
It's surrounded by the water droplet; no oxygen gets through, there are only water molecules.
So it has to be the anode, because if it were the cathode, reduction would occur and it would corrode.
Only iron can react because no O2 is present to react.
The answer is A.
agree with this. That was my logic in the exam :)
This was also my logic in the exam.. At region X oxidation would occur, providing electrons for the reduction reaction which would occur in the presence of Oxygen gas, at region Y.. That whats i was thinking
Post by: shonira on November 15, 2009, 01:52:08 pm
13 I got A. What question was that again?
A for me too.
I looked it up, it's the one about the pipes.
It can't be the reduction of oxygen and water to OH guys.
Look where region X is.
It's surrounded by the water droplet; no oxygen gets through, there are only water molecules.
So it has to be the anode, because if it were the cathode, reduction would occur and it would corrode.
Only iron can react because no O2 is present to react.
The answer is A.
agree with this. That was my logic in the exam :)
This was also my logic in the exam.. At region X oxidation would occur, providing electrons for the reduction reaction which would occur in the presence of Oxygen gas, at region Y.. That whats i was thinking
+1
Post by: herzy on November 15, 2009, 02:09:11 pm
Post by: Ilovemathsmeth on November 15, 2009, 06:26:19 pm
MC was trickier than I thought. Wish I'd allocated more time to it! =(
Post by: herzy on November 15, 2009, 07:34:55 pm
I had A for question 13 as well. I was very confident with that question as absolutely no O2 was in contact with the iron region.
I also had C for 12 as well (positive - positive, negative-negative).
yeh 12 was positive-positive, negative-negative
I got C as well, positive to positive; negative to negative.
MC was trickier than I thought. Wish I'd allocated more time to it! =(
i agree they were tricky - i thought the whole paper was trickier than people give it credit for...
Post by: chima987 on November 15, 2009, 07:53:25 pm
Post by: herzy on November 15, 2009, 08:05:11 pm
Post by: methodsboy on November 15, 2009, 09:13:57 pm
yeah. i got C for both q12 and 13I had A for question 13 as well. I was very confident with that question as absolutely no O2 was in contact with the iron region.
I also had C for 12 as well (positive - positive, negative-negative).
yeh 12 was positive-positive, negative-negative
I got C as well, positive to positive; negative to negative.
MC was trickier than I thought. Wish I'd allocated more time to it! =(
i agree they were tricky - i thought the whole paper was trickier than people give it credit for...
Post by: herzy on November 15, 2009, 09:52:34 pm
yeah. i got C for both q12 and 13I had A for question 13 as well. I was very confident with that question as absolutely no O2 was in contact with the iron region.
I also had C for 12 as well (positive - positive, negative-negative).
sorry methodsboy, but 13 was A not that it matters now...
yeh 12 was positive-positive, negative-negative
I got C as well, positive to positive; negative to negative.
MC was trickier than I thought. Wish I'd allocated more time to it! =(
i agree they were tricky - i thought the whole paper was trickier than people give it credit for...
Post by: /0 on November 26, 2009, 08:32:36 pm
I emailed my chem teacher (who is an assessor), he said fully charged means it's about to discharge.
Oh well, I don't fully agree, but what can you do about it?
Is this his view or what the markers are marking?
I hope they give both.
New word is they will.
=)