ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: andy456 on May 27, 2010, 04:04:54 pm
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Has anyone done this exam yet?? Did you think it was hard??
What did you get??
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i thought multiple choice was quite easy, the short answer questions weren't to hard either although all the draw the structural formula, what must be drawn etc screwed me over. My school actually purchased that exam and made us sit it like the real thing. I think i did pretty good it wasn't too hard and it wasn't too easy. Id say Id get 6X-7X our of 83 + or - 2 which roughly equates to 75-80%.
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STAV i got about 70-80% as well but INSIGHT PAPAER IS SOO HARD T_t
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Yeah multiple choice were easy as... I only got a couple wrong. The short answer werea little tricky. So many stoich calculations. I was doing the exam and went through a mentalblank but 10 mins before the end I had a brain 'wave' and it all came to me. I ended up getting 70% I made quiet a few stupid mistakes. Hopefully I can up that score in the next 2 weeks
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Neap was harder. I reckon STAV was alright apart from the NMR bit of it... a bit too hard for VCE level?
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Neap was harder. I reckon STAV was alright apart from the NMR bit of it... a bit too hard for VCE level?
NMR- do you mean the multi choice question or the short answer question??
There wasn't much on spectroscopy which was good....
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compared to the 09 vcaa paper stav was nothing.
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Did it at school as a trial exam on tuesday and got 90% for it. Lost all my marks on stupid things like states and sig figs ><.
Multi choice were quite easy though, there was some tricky organic stuff towards the end, but nothing too hard i thought.
My hardest exam so far has been CSE 2010.
It had stuff on it i cant find in a textbook or anything and it had a a whole SA question on NMR/Mass spec. and the stoich involved in some of the MC were intense, like involved bits where you had to reduce Fe twice to Fe3+ and weird as stuff i havent encountered before.
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Is 80% for a chem exam good? I keep making silly mistakes costing me 10-13 marks per paper... getting worried.
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Depends what you are aiming for and the difficulty of the paper. If its hard, then wow you did quite well. If it were easy.... eh... not so much. Then again, that is great if you are not aiming for high A or A+ territory.
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Neap was harder. I reckon STAV was alright apart from the NMR bit of it... a bit too hard for VCE level?
NMR- do you mean the multi choice question or the short answer question??
There wasn't much on spectroscopy which was good....
Something about multiplets
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Neap was harder. I reckon STAV was alright apart from the NMR bit of it... a bit too hard for VCE level?
NMR- do you mean the multi choice question or the short answer question??
There wasn't much on spectroscopy which was good....
Something about multiplets
I saw that question..care to refresh my memory of what it meant?
Depends what you are aiming for and the difficulty of the paper. If its hard, then wow you did quite well. If it were easy.... eh... not so much. Then again, that is great if you are not aiming for high A or A+ territory.
Hmm...I was kind of aiming for high A-A+ before...but now.... I think I can do it, but I'm just careless which is the frustrating bit.
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Question 2. If a multiplet is seen in H NMR what is the ester...
Sorry cant remember what the ester was but the previous question made u draw semistructural of ALL esters
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I think I chose the one which would give an environment with more than like, 5 peaks.
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multiplets thankfully are apparently not part of vcaa course.
our teacher emailed around and emailed vcaa and they replied that only simple compounds will be used for NMR analysis.
However for those that were wandering a multiplet is something like >5 splits in the peak.
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84% for this one. Average.?
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However for those that were wandering a multiplet is something like >5 splits in the peak.
Nope. Sextets, Septets, Octets are not classified as multiplets, these are very well defined and commonplace for organic chemistry.
A multiplet generally refer to peaks that are a mess, where a range of things can happen, such as overlapping of different environments, or crazy multiplicity. These makes the splitting pattern impossible to determine, so we throw it in the too hard basket.
The ester in question is propyl methanoate. The second H environment in the propyl is split by a CH3 group and a CH2O group. These two groups are very different, multiplicity dictates there will be a triplet of quartets. Since the environments are fairly different, nice overlapping does not occur, and you end up with literally, a mess. It is impossible to identify from this mess that it is a triplet of quartets, therefore it is classified as a 'multiplet'.
For more info, see http://vcenotes.com/forum/index.php/topic,26044.msg263934.html#new
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I just did this exam and i have some queries with it
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1. Draw the semistructural formula for all esters with the molecular formula C4H8O2.
The solutions say that there are 3 possible esters, HCOOCH2CH2CH3, CH3COOCH2CH3, CH3CH2COOHCH3
However there are actually 4 possible esters
There is also 2-propyl methanoate HCOOCH(CH3)2
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Attached Picture
NaOH absorbs atmospheric CO2 to become NaCO3. However, don't both NaOH and NaCO3 react with HCl? Hence if regardless of how much time has passed and how much NaOH has been converted to NaCO3, the titre of HCl should still be the same?
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Taking a guess, isn't it Na2CO3? Being a carbonate means it requires 2 hydrogens in the reaction, unlike hydroxide which is a one to one ratio. Hence, you would need a larger titre for the carbonate ion.
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Taking a guess, isn't it Na2CO3? Being a carbonate means it requires 2 hydrogens in the reaction, unlike hydroxide which is a one to one ratio. Hence, you would need a larger titre for the carbonate ion.
I guess, but if that's true then you need an even bigger titre of HCl to reach equivalence point.
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yup isnt that what the question said?
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Accoridng to the question, the fresh NaOH in which none of it has become Na2CO3 requires a bigger titre of HCl than the stale NaOH
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oh! my bad. Yea, then ur right><
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you call this an exam? hahahaha
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you call this an exam? hahahaha
wow cocky much?
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you call this an exam? hahahaha
wow cocky much?
haha im kiddin mate ;) i wish i could be cocky at this point in time before the exams >.>
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Am I going stuuupid, or to quote Martoman, is STAV on crack :P.
Firstly
Q 9di. it says name bonding types, other than covelent, which give this protein its structure.
Then in the answers it said you needed di-sulfide. Di sulfide is a covelent BOND!
And also, the covelent bond between the sulfur molecules isn't even present. You have to draw it in yourself in the next question!
Q 7d. If the theoretical mass is 0.273, and the actual mass is 0.268, then doesn't that make the percentage yield lower than 100, or am I just going crazy?
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Q 7d. If the theoretical mass is 0.273, and the actual mass is 0.268, then doesn't that make the percentage yield lower than 100, or am I just going crazy?
lol, yeh, i was like wtf when i saw the answers.
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Well in that case, and considering wikipedia never lies (http://en.wikipedia.org/wiki/Disulfide_bond), then I got 94%. :)
God I hope I can pull something like this on the exam...
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%102...
good, i guess...
Haha
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Lololol stonecold you're right, and i took marks off myself for those things >.<
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btw, for this question, why can't the answer be D?
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D is a tertiary alkanol, which means it can't be oxidised into a carboxilic acid. Aldehyde groups can though, provided that they are the end carbon.
Don't worry, I stuffed up the same question :(
I should have realised that it looked too simple, and our teacher was telling it to us in class last week.
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learnt something new then :)
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Well in that case, and considering wikipedia never lies (http://en.wikipedia.org/wiki/Disulfide_bond), then I got 94%. :)
God I hope I can pull something like this on the exam...
I guess what they were asking was that you don't simply say covalent bonds. Rather you said specifically that it was disulfide, hydrogen etc. It's only a little ambiguous...
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yeah, but the disulfide bond isn't even present until you draw it in the next question.
do these tools expect us to work backwards on the paper...
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lmao I just did this paper.
If only I'm not retard enough to realise we use limited reagent in calculations...I would have gotten a decent score ><.
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just did this paper. nearly stumped by the first short answer -.-
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If you mean their solution, then yeah. They calculated stuff in the wrong order and calculated stuff that didn't need to be there and just over complicated it. Probably one of the worst exams I have seen as far as solutions goes...
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just did this paper. nearly stumped by the first short answer -.-
lol same, then realised it was piss easy.
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The percentage is 98.2, off the top of my head for the percentage yield. My teacher made a fuss about it.
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Just did this exam in class today. We did it as a proper practice exam.. Teacher should've chosen a better exam, this one has so many weird questions, and the solutions ! some are just plain wrong...
I think I lost at least 6-7 marks >.<
The percentage is 98.2, off the top of my head for the percentage yield. My teacher made a fuss about it.
Yep, it was something like that. I saw their solutions, and >100 ?? What! haha, they fail...
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Aldehyde groups can though, provided that they are the end carbon.
Um.... arent aldehydes ALWAYS on the end carbon? Else its a ketone?
Question 3 - on the Multi choice, the answer says 5 (which is option b), but I think it should be 6 (which is option c)
Hexane
2-methylPentane
3-methylPentane
2-ethylButane
2,2-Dimethyl butane
2,3-Dimethyl Butane
Did anybody else get six instead of five?
And question 5 - I am going to be picky.....
three peaks from CH3. four peaks from CH2.
There is your answer seven.
BUT..... doesn't TMS produce a peak? Hence the answer is eight????
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2-ethlybutane is the same as 3-methlypentane.
Yes, aldehydes must be on the terminal carbon.
And with question 5... They didn't say they ran TMS at the same time...
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2-ethlybutane is the same as 3-methlypentane.
shit!!!!!!! you are right. Damnit!
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And with question 5... They didn't say they ran TMS at the same time...
I am fairly sure TMS is always ran, but it's never 'counted'
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Has anyone done Insight 2009?? Is it a difficult exam. I don't think it was....
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NEAP 2010 destroyed me :(
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^Chin up. It destroyed everybody.
And the question where you have to draw in the electrophoresis diagram is too ambiguous Martoman and I have concluded :P!
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Anyone got the 2008 lisachem solutions; I can't find them
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Anyone got the 2008 lisachem solutions; I can't find them
Attached. Enjoy :)
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^Chin up. It destroyed everybody.
And the question where you have to draw in the electrophoresis diagram is too ambiguous Martoman and I have concluded :P!
Was the positioning of serine and glutamic acid CORRECT? It bothered me...
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They say that the one with lower mass will move fastest. Whilst this methodology is probably the most correct, as in DNA gel electrophorosis, different levels of negative charge do not effect the movement of particles, it is their size which does.
However, we interpreted it as amino acid with the greater charge would move more quickly. A little ambiguous for mine...
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I went with the molecular mass bit, but alanine only has a Ch3 group where as the others are larger, so wouldn't they be on the left of alanine? The answer has them on the right.
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Anyone got the 2008 lisachem solutions; I can't find them
Attached. Enjoy :)
Thanks
Anyone got the NEAP 2008 answers???
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i thought the anwsers to stav 2010 were an absolute joke...... insight papers........now they have solutions!
but yea...thought it was pretty easy paper compared to most, i got the highest mark on it that i've gotten for any exam so far
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It was a fair paper. Made stupid mistakes though. Got 91% ...
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Was an okay paper, and yeah, solutions were absolutely dismal.
Their biology papers are worse...
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gunned this paper - my teacher only took 0.5 marks from my short answer although it really should have been one
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highest exam so far is 89% D:
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^your improving :)
by next wednesday you'll be getting even higher!
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am i? :|...hmmmm
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Anyone got the NEAP 2008 answers???
Attached.