ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: crayolé on June 05, 2010, 01:59:56 pm
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Gah I remember a topic a month or so ago about this but I cant find it :/
So what is expected to be on the mid years?
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I think there will be a UV-Vis s.a question
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Probably a question or two on organic chem.
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I think they are gonna have "how many of these statements are correct" questions on AAS since they had it on UV last year in MC
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I'm looking forward to some sadistic DNA hydrolysing questions
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I'm looking forward to some sadistic DNA hydrolysing questions
Single stranded in one question, then double stranded in another. Everyone will ignore those conditions... And lose marks...
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if vcaa want to be dogs they could make us 'draw a a pair of nitrogenous bases showing all bonds'
hate doing them
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Yeah. And to make it worse they'll flip them all around in the data book...
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Yeah. And to make it worse they'll flip them all around in the data book...
they are already flipped in the data book (from a left strand perspective) pisses me off
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Everyone will ignore those conditions... And lose marks...
Keep them percentiles comin' 8-)
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By sadistic dna hydrolysing questions are you referring to a similar sort present in vcaa 2009 that were time consuming and pretty much overall gay?
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Yeah. And to make it worse they'll flip them all around in the data book...
they are already flipped in the data book (from a left strand perspective) pisses me off
huh, what are you talking about?
http://www.vcaa.vic.edu.au/vcaa/vce/exams/examcovers/June_2010_covers/2010chem1-cover.pdf
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There will defs be a pH question, and maybe a find the mass of a molecule question. seen a lot of them.
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Yeah. And to make it worse they'll flip them all around in the data book...
they are already flipped in the data book (from a left strand perspective) pisses me off
huh, what are you talking about?
http://www.vcaa.vic.edu.au/vcaa/vce/exams/examcovers/June_2010_covers/2010chem1-cover.pdf
Just looking at that cover makes me nervous :(
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It says 24 pages and its just 1 less from last year that means the length of the exam is about the same. :S
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Think it's mostly organic.
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It wont get any harder i dont think from last year, maybe a random question here or there in SA worth a mark or two on theory that might throw some people and a few dodgy MC's.
But im pretty sure the some where in last years assessors report in said that the examiners were 'happy' with the standard of difficulty and that it was a 'challenging exam'.
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It wont get any harder i dont think from last year, maybe a random question here or there in SA worth a mark or two on theory that might throw some people and a few dodgy MC's.
But im pretty sure the some where in last years assessors report in said that the examiners were 'happy' with the standard of difficulty and that it was a 'challenging exam'.
With all due respect, I think that's the examiners egos talking.
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Im predicting Ethanol to Ethanoic acid, using Potassium Dichromate or Permanganate.
At least there is one less short answer question in this year's exam.
Density included.
Also ethanol being combusted. This is probably where states mark is hidden.
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huh, what are you talking about?
http://www.vcaa.vic.edu.au/vcaa/vce/exams/examcovers/June_2010_covers/2010chem1-cover.pdf
From a left hand perspective, so the phosphate and deoxyribose is on the left (I just prefer it on the left)
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Im predicting Ethanol to Ethanoic acid, using Potassium Dichromate or Permanganate.
At least there is one less short answer question in this year's exam.
Density included.
Also ethanol being combusted. This is probably where states mark is hidden.
Is this C2H5OH (g) + O2(g) --> 2CO2 (g) + 3H2O(g) ???
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Any alcohol is a liquid.
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Lol assessor's report for Question 7a in VCAA 2008 said that (g) or (l) is acceptable for ethanol and water
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LAWL assessor needs to assess his marking schema.
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=/ But ethanol is being combusted isn't it? Since ethanol has a low boiling point, isn't it a gas at the temperature of combustion?
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I concede your point.
Could be either :)
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I think that only hydrocarbons with only C and H are volatile at room temp, and they must be four carbons or less.
Alkanols, have the polar group, which means they can form h-bonds with other molecules, so generally require more than room temp to become gaseous.
Both (l) and (g) are right though. It depends how you interpret the question. Just before the reaction, ethanol will be gaseous, as it has been heated, however if you interpret before the experiment as in reactants sitting in their container, then it will be liquid.
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Combustion initially happens where the fuel is in the gas phase. Liquids only combust above their flash point. This is where there is enough evaporated fuel to start combustion. For ethanol this is 12.8[sup]o[/sup]C, so it will still mostly be liquid. But you can argue that the actual combustion is with gaseous ethanol.
Though if there is no spark or source of energy to initiate the reaction then the autoignition temperature must be reached. For ethanol this is 365[sup]o[/sup]C I think you'll agree that it will be a gas here.
So yeah, either can be argued.
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I reckon there will be a question asking:
Spell electrophoresis: _________________________ 1 mark.
Examiners report: Many students found this difficult, mainly because they thought it was a trick question.
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I have 2 questions
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1. VCAA 2008 Sample Paper Question
Prior to the experiment, the concentration of the NaOH was experimentally determined by titrating the NaOH against a standard solution of HCl. Suppose about 10mL of the HCl were spilt on the floor during the experiment. How would you safely neutralize the spill
~ Can you say "Add diluted solution of NaOH(aq) to the spill"?
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2. I'm confused about the use of states in "reaction pathways reactions." According to assessor's report for VCAA 2007 Question 5c, you don't have to use states if you use the semistructural formula of the organic compounds involved???
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http://vcenotes.com/forum/index.php/topic,26135.msg264613.html#msg264613
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I have 2 questions
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1. VCAA 2008 Sample Paper Question
Prior to the experiment, the concentration of the NaOH was experimentally determined by titrating the NaOH against a standard solution of HCl. Suppose about 10mL of the HCl were spilt on the floor during the experiment. How would you safely neutralize the spill
~ Can you say "Add diluted solution of NaOH(aq) to the spill"?
You most certainly can. BUTTTT where are you gonna pull that from.. your back pocket?
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im assuming there is gunna be a redox back titration
a lot of organic and reaction pathways
some dna and biofuels
and possibly a gravimetric
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I have 2 questions
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1. VCAA 2008 Sample Paper Question
Prior to the experiment, the concentration of the NaOH was experimentally determined by titrating the NaOH against a standard solution of HCl. Suppose about 10mL of the HCl were spilt on the floor during the experiment. How would you safely neutralize the spill
~ Can you say "Add diluted solution of NaOH(aq) to the spill"?
You most certainly can. BUTTTT where are you gonna pull that from.. your back pocket?
You are performing a titration with it. So it should be easily accessible.
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nah. you don't know its concentration. So you could be putting something really basic on it and damage the floor.
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What did you write then?
Referring to the solutions which stonecold posted, where did sodium hydrogen carbonate come from? And sodium carbonate? lol..
What I wrote (as a joke) was: "Add two drops of methyl red, stir, slowly add NaOH stirring continuously. Cease adding NaOH when colour change is observed." lol
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I wrote add water.
What I wrote (as a joke) was: "Add two drops of methyl red, stir, slowly add NaOH stirring continuously. Cease adding NaOH when colour change is observed." lol
lawl you're sounding more like me every day.
Also, its standard (hahaha funny pun) to have those things around when doing acid base for spills. >.<
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If this is wrong then I lost two marks :tickedoff: But I reckon the examiner would've given it to me... If only for the humour of it.
The other mark was for thinking dilution => change mole amount XD first question...
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Why cant you add a weak base?
E.g. water???
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You can add water.
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Also, its standard (hahaha funny pun) to have those things around when doing acid base for spills. >.<
I never knew this. We had no such things when we performed titrations at school, though I suppose we used dilute stuff...
Why cant you add a weak base?
E.g. water???
The solutions provided by stonecold had that as an option. "further dilute the spill with a small volume of water, then wipe."
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Also, its standard (hahaha funny pun) to have those things around when doing acid base for spills. >.<
I never knew this. We had no such things when we performed titrations at school, though I suppose we used dilute stuff...
Why cant you add a weak base?
E.g. water???
A tiny bit of common sense will tell you to do so? diluted reduces concentration?
The solutions provided by stonecold had that as an option. "further dilute the spill with a small volume of water, then wipe."
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Also, its standard (hahaha funny pun) to have those things around when doing acid base for spills. >.<
I never knew this. We had no such things when we performed titrations at school, though I suppose we used dilute stuff...
Why cant you add a weak base?
E.g. water???
A tiny bit of common sense will tell you to do so? diluted reduces concentration?
The solutions provided by stonecold had that as an option. "further dilute the spill with a small volume of water, then wipe."
I always thought the sample papers were edited questions from the old study design. I dont think that type of question will be asked on the new study design though
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You add copious amount of water.
You don't add NaOH because then you might have the problem of having a (very) basic solution on the floor!
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That doesn't neutralise it. Simply spreads it all out....
Just do your titration on the floor :P
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hahaha stuff using equipment, just pour the NaOH straight from the bottle and estimate how much you poured as the titre.
But I'm pretty sure adding water...copious amount(love that word) plus some weak base (forgot that bit haha that's why I fail) is sufficient.
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Nah, water does neutralise it, add enough and you can get a pH close enough to 7.
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That doesn't neutralise it. Simply spreads it all out....
Just do your titration on the floor :P
slight problem we don't know how much acid is on the floor for a proper titration. (But I love your answer, in fact I might post it on facebook for lolz)
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Nah, water does neutralise it, add enough and you can get a pH close enough to 7.
water can range from 6.5 to 8.5 ;)
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Yeah however my teacher said to mention weak base aswell, just a bit.
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Just to add to before, there are more marks this year, 75 instead of 73? What I don't understand is, 2008 was 78, but was easier. Is this due to the difficulty of the multiple choice in 2009 that made it a "long exam"?
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Just to add to before, there are more marks this year, 75 instead of 73? What I don't understand is, 2008 was 78, but was easier. Is this due to the difficulty of the multiple choice in 2009 that made it a "long exam"?
The mark allocations were just not that generous
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Also the fact that there were 10 different questions, the actual marks don't make that much difference to the length, but having 10 question stems to read and comprehend makes it long, I think.
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personally to be honest .. i found 2008 so much harder than 2009
lol .... i got 78% on 2008 .. and 92% on 2009 ..... the multiple choice in 2009 was straight forward .. only like 2-3 calculation questions ... everything else was basic .. i dont know how the a+ mark was 78% and the year before was 87% .....
my theory is ... there was ALOT of dumb people who sat chem last year ....putting the averages down etc etc ... hmmm
idk maybe i learned everything between the 2 days of study in between these trail exams
hmmm ... i doubt it ... i think its because ... in 2008 .. there was a lot more mol calculations than in 2009 ...
2009 was like .. apply knowledge and hydrocarbon business .. i dont even remember one question on bio fuels
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personally to be honest .. i found 2008 so much harder than 2009
lol .... i got 78% on 2008 .. and 92% on 2009 ..... the multiple choice in 2009 was straight forward .. only like 2-3 calculation questions ... everything else was basic .. i dont know how the a+ mark was 78% and the year before was 87% .....
my theory is ... there was ALOT of dumb people who sat chem last year ....putting the averages down etc etc ... hmmm
idk maybe i learned everything between the 2 days of study in between these trail exams
hmmm ... i doubt it ... i think its because ... in 2008 .. there was a lot more mol calculations than in 2009 ...
2009 was like .. apply knowledge and hydrocarbon business .. i dont even remember one question on bio fuels
Could have been because the hype of 2009 exam being so hard was in your mind and you studied extra hard for it?
My theory: 2008 exam was the first year for the new course and always first year for new course is easy exam. Like was the case with physics last year.
So people werent prepared for 2009. They thought it would be another walk in the park but they got well..pwned.
In your mind you knew 2009 was hard from all the talk about it, prepared extra hard for it and did really good ^^.
yep good theory :D
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Mm I kind of hope this year's Physics is as ahrd to finish on time like Chem 2009, since none of the Physics exams (except VCAA 2006) have really pushed me for time.
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Mm I kind of hope this year's Physics is as ahrd to finish on time like Chem 2009, since none of the Physics exams (except VCAA 2006) have really pushed me for time.
urgh cbf with physics i just wanna finish it quickly
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personally to be honest .. i found 2008 so much harder than 2009
lol .... i got 78% on 2008 .. and 92% on 2009 ..... the multiple choice in 2009 was straight forward .. only like 2-3 calculation questions ... everything else was basic .. i dont know how the a+ mark was 78% and the year before was 87% .....
my theory is ... there was ALOT of dumb people who sat chem last year ....putting the averages down etc etc ... hmmm
idk maybe i learned everything between the 2 days of study in between these trail exams
hmmm ... i doubt it ... i think its because ... in 2008 .. there was a lot more mol calculations than in 2009 ...
2009 was like .. apply knowledge and hydrocarbon business .. i dont even remember one question on bio fuels
COULDN'T AGREE WITH YOU MORE!
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I think 2009 was a great exam. You don't want piss-easy exams like what I've heard about last years physics or even our non-cas methods ones....
because the careless mistakes will shoot you down!
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I think 2009 was a great exam. You don't want piss-easy exams like what I've heard about last years physics or even our non-cas methods ones....
because the careless mistakes will shoot you down!
Yeah agreed, cause then everyone will ace it if its too easy.
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Just thought that they could ask us a question in which the yield is over 100%... like in a gravimetic analysis and we have to realise that the added weight was because of say water residue. That would have most going 0.o.... OVER 100%??!?!?!?
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Lol, I'd probably check again if it's >100...
I think they'll give one where the yield is OVER 9000.