ATAR Notes: Forum
Archived Discussion => 2012 => Mid-year exams => Exam Discussion => Victoria => Chemistry => Topic started by: thushan on June 13, 2012, 09:00:54 pm
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Here it is!
Sorry for delay, I was studying.
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Out come the irrefutable suggested solutions!
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thanks thushan!!
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ps. If i did something stupid with the balancing of the combustion in q1biii, but got all the states right, would I get 1 or 0?
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1...
1 woudl be for balancing, 1 for everything else :\
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I think you had some Unit 4 stuff in that file. D:
Thanks for the solutions aswell. :)
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1...
1 woudl be for balancing, 1 for everything else :\
hmm, but if you look at other examiners reports, they always say 1 mark if one or more states correct
0 marks if incorrect equation
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Thanks for also giving us a look at the UNIT 4 chem book solutions you've been doing by the looks of it hahah
and what was the 'cook' reference to?!
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I think you had some Unit 4 stuff in that file. D:
Thanks for the solutions aswell. :)
LOLOL good point-out! Idiot me!
I took an old file that I'm using for my model solutions for my Unit 4 book.
Congratulations, you just got a glimpse of my unit 4 book LOL!
And Bhootnike - nah i was writing CH3COOK and i was like...LOL COOK
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I think you had some Unit 4 stuff in that file. D:
Thanks for the solutions aswell. :)
LOLOL good point-out! Idiot me!
I took an old file that I'm using for my model solutions for my Unit 4 book.
Congratulations, you just got a glimpse of my unit 4 book LOL!
And Bhootnike - nah i was writing CH3COOK and i was like...LOL COOK
cant wait for the book!! as nerdy as that sounds lol first time being excited for a book.. ever
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To be honest, When I saw there was more in that document, I nearly got scared thinking that I left a whole page blank.
Haha. :)
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just out of curiousity,
shouldn't it be KCH3COO
as metals are supposed to be b4 others?
(didn't write that on exam as i knew convention dictates the other way)
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just out of curiousity,
shouldn't it be KCH3COO
as metals are supposed to be b4 others?
(didn't write that on exam as i knew convention dictates the other way)
either is fine haha
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When is the Unit 4 book coming out?
After my poor performance today, I can't wait to get stuck into Unit 4 and year it apart.
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yess UNIT 4 BOOK is gonna be sweeetums!
I think you had some Unit 4 stuff in that file. D:
Thanks for the solutions aswell. :)
And Bhootnike - nah i was writing CH3COOK and i was like...LOL COOK
hahah, i like it ;)
reply to my PM when you can too haha, :p
Thanks for the solutions thushan! looking at them, i think the exam had some fine points, e.g. how states had to be liquid only..
:S
But yeah , appreciate it!
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uggh..is it possible that the vcaa examiners will accept other structural formulas such as ones showing all bonds?
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thanks for the solutions thushan!
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uggh..is it possible that the vcaa examiners will accept other structural formulas such as ones showing all bonds?
yeah defs - i just ceebed getting my other computer out to draw the structural formula haha
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ps. If i did something stupid with the balancing of the combustion in q1biii, but got all the states right, would I get 1 or 0?
So I'm not the only one?
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ps. If i did something stupid with the balancing of the combustion in q1biii, but got all the states right, would I get 1 or 0?
So I'm not the only one?
0/2 I think
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Sorry for delay, I was studying.
FOR WHAT!?!?!
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Chemderp did you stuff up the equation? Everyone is dropping the silliest marks! :(
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ps. If i did something stupid with the balancing of the combustion in q1biii, but got all the states right, would I get 1 or 0?
So I'm not the only one?
0/2 I think
Shit...why 0? Not even 1?
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For the testing wether or not the propyl propanoate is pure, could you use HPLC??
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Hey for the combustion reaction: My states were right and all of the coefficients of my equation were right except, i put 52 infront of the O2 (should've been 26). Still not worth a mark?
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Hey for the combustion reaction: My states were right and all of the coefficients of my equation were right except, i put 52 infront of the O2 (should've been 26). Still not worth a mark?
that should be worth 1 mark, i think thushan thought u made a crazy crazy mistake like combusting ethanol or something lol
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Can anyone explain to me why propanol would be wrong?
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Can anyone explain to me why propanol would be wrong?
the systematic name of propanol is wrong, its either propan-1-ol or propan-2-ol and propan-2-ol does not form propanoate
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For the testing wether or not the propyl propanoate is pure, could you use HPLC??
HPLC should be fine I think.
About the states vs balanced...if balancing is wrong, then 0/2 sorry... :( it's from a past assessors report:
"Two marks were awarded for a correct balanced equation with all states correct, one mark was awarded for a correct
balanced equation with one or more states missing or incorrect, and no marks were awarded for an incorrect equation."
It's a sucky marking scheme... :(
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ps. If i did something stupid with the balancing of the combustion in q1biii, but got all the states right, would I get 1 or 0?
So I'm not the only one?
0/2 I think
Hmm, fair enough, a little disappointing, but just pick up the slack for unit 4!
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^ yeah dude lets rape the unit 4 exams
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with working out the average iron content in the tablets, shouldn't the answer be 30mg as opposed to 36?
Because they gave us a standard solution of concentration 0.00g/L of tablet that still absorbed some of the radiation (0.006 abs), implying some Fe was present as impurities in the water used to dissolve the tablets (it also didn't say 'deionized water')... Then if we're working out the amount of Fe in the tablets, wouldn't you need to discount the amount of impurity also absorbing some radiation (equivalent to 6mg of Fe in the water)?
Or is that looking too much into it?
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For stearic acid could the state be a gas? :/
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How many marks would I lose if I wrote tristearic acid instead of stearic acid and my balancing was out by a factor of 3?
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with working out the average iron content in the tablets, shouldn't the answer be 30mg as opposed to 36?
Because they gave us a standard solution of concentration 0.00g/L of tablet that still absorbed some of the radiation (0.006 abs), implying some Fe was present as impurities in the water used to dissolve the tablets (it also didn't say 'deionized water')... Then if we're working out the amount of Fe in the tablets, wouldn't you need to discount the amount of impurity also absorbing some radiation (equivalent to 6mg of Fe in the water)?
Or is that looking too much into it?
It could also be an absorbance of the cell... that's the point of using a 'blank' initially. I didn't take off 6mg, but others did and I think they are right..
- Stone
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with working out the average iron content in the tablets, shouldn't the answer be 30mg as opposed to 36?
Because they gave us a standard solution of concentration 0.00g/L of tablet that still absorbed some of the radiation (0.006 abs), implying some Fe was present as impurities in the water used to dissolve the tablets (it also didn't say 'deionized water')... Then if we're working out the amount of Fe in the tablets, wouldn't you need to discount the amount of impurity also absorbing some radiation (equivalent to 6mg of Fe in the water)?
Or is that looking too much into it?
It could also be an absorbance of the cell... that's the point of using a 'blank' initially. I didn't take off 6mg, but others did and I think they are right..
- Stone
err, nah they'd be wrong
It's because it says the concentration is 0 when you have absorbance at 0.06. Impurities were therefore never counted as part of the concentration.
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hi there, jst a few confusing points, for the fatty acid identification question, i put down stearic instead of stearic acid, is that goin to get me zero marks? for the technique to identify the pure propyl ester i put down hplc, instead of glc, and one last mistake i think i made was that i chose to describe IR spectroscope as the technique we learnt this unit and i only mentioned bond energy instead of bond length and strength, is that wrong?
sorry, that i have many questions, im a bit nervous.
Thank you!
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Posted by: Louise clover
« on: 9 hours ago » Insert Quote
hi there, jst a few confusing points, for the fatty acid identification question, i put down stearic instead of stearic acid, is that goin to get me zero marks? for the technique to identify the pure propyl ester i put down hplc, instead of glc, and one last mistake i think i made was that i chose to describe IR spectroscope as the technique we learnt this unit and i only mentioned bond energy instead of bond length and strength, is that wrong?
sorry, that i have many questions, im a bit nervous.
Thank you!
-I did the exact same thing...
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how many marks would they take off if i have the correct balanced equation but maybe one or more wrong states?
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how many marks would they take off if i have the correct balanced equation but maybe one or more wrong states?
you'd get 1/2
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hi there, jst a few confusing points, for the fatty acid identification question, i put down stearic instead of stearic acid, is that goin to get me zero marks? for the technique to identify the pure propyl ester i put down hplc, instead of glc, and one last mistake i think i made was that i chose to describe IR spectroscope as the technique we learnt this unit and i only mentioned bond energy instead of bond length and strength, is that wrong?
sorry, that i have many questions, im a bit nervous.
Thank you!
stearic? hmm that'd be touch and go. i'd pay it, but I'm not sure of the chief examiner though. chances are he'll pay it, apparently he's quite fair
bond energy is fine. bond length, strength, energy, they're talking about the same thing. as for hplc, you may get away with it, i'm not entirely sure.
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how do we get consequencial marks in a chemistry exam, because i put down propanol instead of propan-1-ol, and i did the same thing in the flowchart that describes how we could extract pure propyl propanoate, but when i write down the semistructural formulae, i put down propan-1-ol. would i loose alot of marks for this? :-\
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hi there, jst a few confusing points, for the fatty acid identification question, i put down stearic instead of stearic acid, is that goin to get me zero marks? for the technique to identify the pure propyl ester i put down hplc, instead of glc, and one last mistake i think i made was that i chose to describe IR spectroscope as the technique we learnt this unit and i only mentioned bond energy instead of bond length and strength, is that wrong?
sorry, that i have many questions, im a bit nervous.
Thank you!
stearic? hmm that'd be touch and go. i'd pay it, but I'm not sure of the chief examiner though. chances are he'll pay it, apparently he's quite fair
bond energy is fine. bond length, strength, energy, they're talking about the same thing. as for hplc, you may get away with it, i'm not entirely sure.
thank you so much thushan!
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hi there, jst a few confusing points, for the fatty acid identification question, i put down stearic instead of stearic acid, is that goin to get me zero marks? for the technique to identify the pure propyl ester i put down hplc, instead of glc, and one last mistake i think i made was that i chose to describe IR spectroscope as the technique we learnt this unit and i only mentioned bond energy instead of bond length and strength, is that wrong?
sorry, that i have many questions, im a bit nervous.
Thank you!
stearic? hmm that'd be touch and go. i'd pay it, but I'm not sure of the chief examiner though. chances are he'll pay it, apparently he's quite fair
bond energy is fine. bond length, strength, energy, they're talking about the same thing. as for hplc, you may get away with it, i'm not entirely sure.
thank you so much thushan!
no worries!
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Hi guys, for the question that asked how the sample can be tested to be pure I wrote GC but said something along the lines of:
If only one peak is present in addition to the carrier gas peak (assuming carrier gas produces a peak) then the sample is likely to be pure.
Last night I just remembered that the carrier gas is inert and won't produce a peak... So I'm wondering if I would get atleast 1 mark out of the 2 marks allocated for the question?
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Hi guys, for the question that asked how the sample can be tested to be pure I wrote GC but said something along the lines of:
If only one peak is present in addition to the carrier gas peak (assuming carrier gas produces a peak) then the sample is likely to be pure.
Last night I just remembered that the carrier gas is inert and won't produce a peak... So I'm wondering if I would get atleast 1 mark out of the 2 marks allocated for the question?
Defs. Your answer was fine apart from that minor slip up. 1/2
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Thanks Thushan, that puts me at ease. =)
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for question 7 i miss calculated the mass of lead iodide, i think i might have calculated mols instead or something lol. obviously i wasn't thinking. but would i get consequential marks for the next part if i used my answer from part iii to get an answer to iv if i did everything correct in part iv?
apart from that i got everything pretty much, but i reckon i'll lose a few marks on explain question. but can't believe i made that mistake above.... do u reckon i can still get 3 marks on part a. iv of question 7 though. im really worried about this, cause im not sure about consequential marks in chem.
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for question 7 i miss calculated the mass of lead iodide, i think i might have calculated mols instead or something lol. obviously i wasn't thinking. but would i get consequential marks for the next part if i used my answer from part iii to get an answer to iv if i did everything correct in part iv?
apart from that i got everything pretty much, but i reckon i'll lose a few marks on explain question. but can't believe i made that mistake above.... do u reckon i can still get 3 marks on part a. iv of question 7 though. im really worried about this, cause im not sure about consequential marks in chem.
i think you'd get full marks for part iv
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for question 7 i miss calculated the mass of lead iodide, i think i might have calculated mols instead or something lol. obviously i wasn't thinking. but would i get consequential marks for the next part if i used my answer from part iii to get an answer to iv if i did everything correct in part iv?
apart from that i got everything pretty much, but i reckon i'll lose a few marks on explain question. but can't believe i made that mistake above.... do u reckon i can still get 3 marks on part a. iv of question 7 though. im really worried about this, cause im not sure about consequential marks in chem.
i think you'd get full marks for part iv
thanks thusan that makes me feel better, i was kicking myself over that mistake cause i thought i would lose 4 marks cause of it. what do u reckon a score of about 70/75 would get me study score wise, if was around the same mark next exam as well and im ranked number 2 in a very strong cohort.
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for question 7 i miss calculated the mass of lead iodide, i think i might have calculated mols instead or something lol. obviously i wasn't thinking. but would i get consequential marks for the next part if i used my answer from part iii to get an answer to iv if i did everything correct in part iv?
apart from that i got everything pretty much, but i reckon i'll lose a few marks on explain question. but can't believe i made that mistake above.... do u reckon i can still get 3 marks on part a. iv of question 7 though. im really worried about this, cause im not sure about consequential marks in chem.
i think you'd get full marks for part iv
thanks thusan that makes me feel better, i was kicking myself over that mistake cause i thought i would lose 4 marks cause of it. what do u reckon a score of about 70/75 would get me study score wise, if was around the same mark next exam as well and im ranked number 2 in a very strong cohort.
Hard to say, I would hazard a guess at 43-46?
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Hey thush these solutions are amazing man! Thanks a heap. :)
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hey thushan, not sure if this has been mentioned, but there's an error in Q4b of your short-answer. It's 1-propanol and not ethanol. don't worry, i made that mistake in my exam too, managed to change it just before time's up :P
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i did almost everything in pencil, does that mean i am going to get penalised?? :-\
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hey thushan, not sure if this has been mentioned, but there's an error in Q4b of your short-answer. It's 1-propanol and not ethanol. don't worry, i made that mistake in my exam too, managed to change it just before time's up :P
ah yes forgot to put that extra ch2.
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i did almost everything in pencil, does that mean i am going to get penalised?? :-\
Nah. The problem with pencil is that the pencil (if written lightly) may not come out in the scanner properly.
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for this equation, CH3CH2OH (l) + CH3CH2COOH (l) -> CH3CH2COOCH2CH3 (l) + H2O (l), i made the states of propanol and propanoic acid and the ester aqueous, it that wrong?
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for this equation, CH3CH2OH (l) + CH3CH2COOH (l) -> CH3CH2COOCH2CH3 (l) + H2O (l), i made the states of propanol and propanoic acid and the ester aqueous, it that wrong?
i actually kinda made a mistake it's meant to be:
CH3CH2CH2OH (l) + CH3CH2COOH (l) -> CH3CH2COOCH2CH2CH3 (l) + H2O (l)
and yeah, they can't be aqueous, otherwise basically no ester will be produced (you'll learn the reason for this in unit 4)
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Thanks for the solutions :) I was just wondering if OH- (aq) + HCl (aq) ---> H20 (l) + Cl- (aq) would be acceptable for question 8a?
And also for question 4d would it be okay to use GC but expect two peaks with one being for the solvent and one with the same retention time as a a sample of know pure propyl propanoate?
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Thanks for the solutions :) I was just wondering if OH- (aq) + HCl (aq) ---> H20 (l) + Cl- (aq) would be acceptable for question 8a?
And also for question 4d would it be okay to use GC but expect two peaks with one being for the solvent and one with the same retention time as a a sample of know pure propyl propanoate?
Hey - haha I think i wrote that "any variant can be written (for the OH- + H+ --> H2O qn) so long as you don't include random species" keeping your answer (you put it on the discussion thread) :P -- I think your answer is fine :)
As for the GC one - there is no solvent - you'd directly inject the reaction mixture!
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Okay thank you! :)
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In my answer to the question asking about determining whether the sample of propyl propanoate was pure or not, I ended up crossing out the entire answer (which took up all of the allocated writing room,) and rewriting my answer in 2 small dot points in a small nook above the question, with an arrow pointing to it. Also written in a different colour pen from the rest of the page.
The answer itself is fine afaik (just mentioned GC and regarding number of peaks present (and rt times compared to database)), but will the assessors be unmotivated to award the 2 marks if it is a bit harder for them to understand what/how I have answered?
Just a little worried that they will take off the marks because I made it harder for them.
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In my answer to the question asking about determining whether the sample of propyl propanoate was pure or not, I ended up crossing out the entire answer (which took up all of the allocated writing room,) and rewriting my answer in 2 small dot points in a small nook above the question, with an arrow pointing to it. Also written in a different colour pen from the rest of the page.
The answer itself is fine afaik (just mentioned GC and regarding number of peaks present (and rt times compared to database)), but will the assessors be unmotivated to award the 2 marks if it is a bit harder for them to understand what/how I have answered?
Just a little worried that they will take off the marks because I made it harder for them.
No way! Assessors aren't allowed to penalise answers that are correct just because they feel like it.
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No way! Assessors aren't allowed to penalise answers that are correct just because they feel like it.
I only hope that what I wrote in my frenzy was legible.... :)
Also, in the explanation of any spectroscopic technique, I chose UV/VIS spectroscopy, and my explanation is almost identical to your's....but I made the silly error of saying outer shell electrons, not the electrons between covalent bonds....I'm guessing that's a mark gone. :( would that be a correct assumption? haha
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If you get 80%, is it possible to get over 40?
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80% will most likely be a low A, so it is still possible to get over 40 if you destroy the unit 4 exam like get a very high A+
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I think 80% is middle range A this year.
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does anyone know what was the exam out of for chem?
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out of 75
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does anyone know what was the exam out of for chem?
75.