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March 19, 2024, 03:55:28 pm

Author Topic: SUGGESTED ANSWERS!!!  (Read 40896 times)

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Shenz0r

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Re: SUGGESTED ANSWERS!!!
« Reply #30 on: June 13, 2012, 04:38:26 pm »
I think the main problem with this exam was that, if people found it extremely easy, they could've rushed through it without adequately checking.

I was so paranoid about there being tricks for each question that I didn't have time to check through all of my solutions after I had finished the exam.

The solubility question, I got 289 the first time and I was like, "that's a pretty big number". Paranoid that I did something wrong, I crossed my working out from the previous question and did it through a different method and got the same answer. So I wasted time crossing out my working for nothing basically =="

I'd say that the exam is on par with the 2008 and 2010 exams, maybe even easier.

There was a VCAA supervisor who looked like Dumbledore at our school. :)
« Last Edit: June 13, 2012, 04:40:45 pm by Shenz0r »
2012 ATAR: 99.20
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2016-2019: Doctor of Medicine (MD4) at The University of Melbourne

afridilegend

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Re: SUGGESTED ANSWERS!!!
« Reply #31 on: June 13, 2012, 04:42:24 pm »

I'd say that the exam is on par with the 2008 and 2010 exams, maybe even easier.

There was a VCAA supervisor who looked like Dumbledore at our school. :)

Anyone know what was the A+ cut-off score for 2010/2008??

Shenz0r

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Re: SUGGESTED ANSWERS!!!
« Reply #32 on: June 13, 2012, 04:45:26 pm »
2008 was 87%, 2010 was 89%.
2012 ATAR: 99.20
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charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #33 on: June 13, 2012, 04:51:16 pm »
Honestly I reckon the cutoff will be less than it was for those two years. I did perfectly on those two exams because they were pretty straightforward with no questions to really trip you up, whereas today there were a number of questions which probably exposed the lack of solidarity in my working. And I reckon (or at least I hope) that will have been a common theme throughout the state.
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charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #34 on: June 13, 2012, 05:09:14 pm »
1.B
2.C
3.D
4.B
5.D
6.A
7.C
8.D
9.A
10.A
11.A
12.C
13.C
14.B
15.B
16.C
17.D
18.C
19.B
20.D


1ai. Glucose (or beta glucose if you prefer)
1ii. 2CH3CH2OH(aq) + 2CO2(g). I antagonistically wrote enzymes over the reaction arrow too, which in hindsight was probably not a particularly bright idea.
1iii. C2H4(g) + H2O(g)  ------H3PO4----> CH3CH2OH(l)

1bi) 3 fatty acids and 1 glycerol
ii) Stearic acid
iii) C18H36O2(l) + 26O2(g) ---->  18CO2(g) + 18 H2O(g)

2a) Tyrosine
b) The lower of the two dots in the middle.
c) Solvent G did not separate alanine and threonine and hence they produced only a single spot with the same Rf value, and three spots for Chromatogram I overall. Solvent F then differentiated between alanine and threonine so that they both produced individual spots with different Rf values. Whilst alanine and arginine had identical Rf values under Solvent F they had been separated by Solvent G and hence Chromatogram II had an additional spot and four spots overall.

3a) H2N-(CH2)6-NH2
b) Amide
bii) Amide/Peptide
c) Ceebs typing this up right now.


4a) Propan-1-ol and Propanoic acid
b) CH3CH2OH(l) + CH3CH2COOH (l) ----H2SO4(l)---> CH3CH2COOCH2CH2CH3 (l) + H2O(l)
c) Obtain a pure sample of propan-1-ol. Oxidise half of this sample using acidified dichromate to obtain propanoic acid. React propanoic acid with the remaining half of propan-1-ol in the presence of concentrated sulfuric acid to obtain propyl propanoate. Distil this product to obtain pure propyl propanaote.
d) Obtain an IR spectrum of the product. If it does not depict an O-H (acid) absorption band or O-H (alcohol) absorption band it can be said to be pure as any contamination from the reactants propanoic acid and propan-1-ol respectively would result in these absorption bands being present in the IR spectrum of the final product.

5a) 2
ii) 3
iii) 6
b) Oxygen and Hydrogen (Although VCAA may accept and even prefer O-H)
c) <Insert Propan-2-ol structure>

6a) You'll have to draw your own graph :P
ii) 36mg
b) UV-Visible Spectroscopy: The level of absorbance of certain wavelengths of light in the UV-Visible region can be used to assess the concentration of compounds which absorb in that specific wavelength. Throw in something about electrons moving to a higher energy level.

7a) Pb2+ aq) + 2I-(aq) ---> PbI2(s)
ii) To ensure that all water had been removed from the precipitate and was not contributing to the mass weighed.
iii) 0.0939g
iv) 0.331g
b) Nitrates are soluble in water with lead (II) cations and vice-versa and hence no precipitate was formed.

8a) NaOH(aq) + HCL(aq) ---> NaCL(aq) + H2O (l)
ii) 0.0400mol
iii) 0.00216mol
iv) 0.0270mol
v) 289g/L

b)Lower because a greater titre of HCl would be required resulting in the amount of NaOH in excess being calculated as greater than its actual value and the amount reacted with ammonium chloride to be less than its actual value. Hence the mass of ammonium chloride dissolved in solution will appear to be less than it really is.

DISCLAIMER: I didn't answer the questions exactly like this in the actual exam, unfortunately. A few of my response questions here are less detailed and would probably not obtain full marks.
« Last Edit: June 13, 2012, 06:38:07 pm by charmanderp »
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Tonychet2

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Re: SUGGESTED ANSWERS!!!
« Reply #35 on: June 13, 2012, 05:10:09 pm »
Honestly I reckon the cutoff will be less than it was for those two years. I did perfectly on those two exams because they were pretty straightforward with no questions to really trip you up, whereas today there were a number of questions which probably exposed the lack of solidarity in my working. And I reckon (or at least I hope) that will have been a common theme throughout the state.
people woulda choked on the propan-1-ol question and drawing the polymer of the alkene addition reaction im geussing

charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #36 on: June 13, 2012, 05:13:25 pm »
Honestly I reckon the cutoff will be less than it was for those two years. I did perfectly on those two exams because they were pretty straightforward with no questions to really trip you up, whereas today there were a number of questions which probably exposed the lack of solidarity in my working. And I reckon (or at least I hope) that will have been a common theme throughout the state.
people woulda choked on the propan-1-ol question and drawing the polymer of the alkene addition reaction im geussing
Perhaps.
University of Melbourne - Bachelor of Arts majoring in English, Economics and International Studies (2013 onwards)

Bhootnike

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Re: SUGGESTED ANSWERS!!!
« Reply #37 on: June 13, 2012, 05:16:42 pm »
wasnt carboxyl group a functional group for the nylon question?
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charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #38 on: June 13, 2012, 05:18:06 pm »
wasnt carboxyl group a functional group for the nylon question?
No because the monomers were linked via amide groups, which arose from reactions bewteen carboxyl groups and amino groups. So they weren't present anymore since after condensation a water molecules comes out, etc.
University of Melbourne - Bachelor of Arts majoring in English, Economics and International Studies (2013 onwards)

Tonychet2

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Re: SUGGESTED ANSWERS!!!
« Reply #39 on: June 13, 2012, 05:19:16 pm »
wasnt carboxyl group a functional group for the nylon question?
No because the monomers were linked via amide groups, which arose from reactions bewteen carboxyl groups and amino groups. So they weren't present anymore since after condensation a water molecules comes out, etc.
this.

howd u find the exam charmander?

Bhootnike

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Re: SUGGESTED ANSWERS!!!
« Reply #40 on: June 13, 2012, 05:21:21 pm »
the question was: "name the functional groups that link the monomers in nylon and protein"
i perceived that as, name the functional groups in the monomers, that link up to make nylon and protein.
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charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #41 on: June 13, 2012, 05:23:45 pm »
wasnt carboxyl group a functional group for the nylon question?
No because the monomers were linked via amide groups, which arose from reactions bewteen carboxyl groups and amino groups. So they weren't present anymore since after condensation a water molecules comes out, etc.
this.

howd u find the exam charmander?
During the exam I thought it was really difficult but that I'd get managed to get everything right. Afterwards realised that it was quite straightforward but I'd dropped a good number of marks due to rather mundane errors. Yourself?
University of Melbourne - Bachelor of Arts majoring in English, Economics and International Studies (2013 onwards)

Tonychet2

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Re: SUGGESTED ANSWERS!!!
« Reply #42 on: June 13, 2012, 05:25:48 pm »
wasnt carboxyl group a functional group for the nylon question?
No because the monomers were linked via amide groups, which arose from reactions bewteen carboxyl groups and amino groups. So they weren't present anymore since after condensation a water molecules comes out, etc.
this.

howd u find the exam charmander?
During the exam I thought it was really difficult but that I'd get managed to get everything right. Afterwards realised that it was quite straightforward but I'd dropped a good number of marks due to rather mundane errors. Yourself?

i got question 5 in the mc wrong, everything else i wrote here is what i put on the exam, on which questions did u make errors did u make if u dont mind me asking???

charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #43 on: June 13, 2012, 05:27:10 pm »
To be honest I'd rather not talk about them :/ Nothing personal, I just can't don't feel like acknowledging them outside of my mind if you know what I mean.
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Tonychet2

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Re: SUGGESTED ANSWERS!!!
« Reply #44 on: June 13, 2012, 05:27:59 pm »
To be honest I'd rather not talk about them :/ Nothing personal, I just can't don't feel like acknowledging them outside of my mind if you know what I mean.

ok no problem privacy respected!