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Archived Discussion => VCE Exam Discussion 2017 => Results Discussion => Victoria => VCE Science Exams => Topic started by: Joseph41 on November 14, 2017, 09:02:58 am
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SECTION A (supplied by keltingmeith, annoy him if you have concerns, not Joseph, alternatively message in the thread)
1 D
2 C
3 D*
4 B
5 B
6 C
7 B
8 A
9 C
10 C/D**
11 C
12 C
13 A***
14 D
15 C****
16 A***
17 C
18 A
19 D*****
20 D
21 Missing from scans :(
22 Missing from scans :(
23 A
24 C
25 C***
26 A
27 A
28 B
29 D
30 C******
*Question 3 is weird. A hydrolytic reaction is one which requires water to take place. A and B are examples of condensation reactions (create water), so definitely wrong. C is the definition of a condensation reaction, and so shouldn't be right either. D is not the only example of a hydrolytic reaction, however it's the only answer that is definitely a hydrolytic reaction, so that's the answer I've gone with.
**Question 10 is also weird - A and B aren't the answer because they only carry one charge. There's no reason to believe that C or D a preferable answer, because they're both in a zwitterionic form. Potentially, C is the preferred answer, because all ionizable groups and ionized. But, D could be preferred because it's charge balanced - indicating what it would look like without the influence of any acids or bases. So, I'm not really sure which VCAA would want.
***Unsure, as a product of not seeing a text book since the new study design. Feel free to debate this.
****Once again, funny question. It's not D, since denaturation doesn't affect the primary structure, and it's not A for the same reason. The mody metabolises alcohol, so it's not B. C is what's left, but I don't think that's technically true, because not all of the bonds are necessary going to be affected, but it's the closest to being true, so.
*****Q19, tbh, is just totally up for debate. Their use of the word qualitative is poorly chosen - qualitative in what sense? B and C are out because they're not appropriate (not necessarily reliable sources), and I only chose D over A because A seems like it's not qualitative beyond "this one has higher numbers".
******I hate electrochem, and this is one damn tedious question. I think silver and gold should produce the most amount by mole based on the fact that aluminium and tin require 3x and 2x the amount of electrons to become solid. Since gold is also the heaviest metal of the four, I think this should be answer, but I am very ready for you guys to debate against me here.
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That was a really messed up exam
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And we couldn’t even bring a dictionary, “feastabilily”
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it was suprisingly more theory based????? little to no calculation.. weird!
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it was suprisingly more theory based????? little to no calculation.. weird!
Yeah there was hardly any calculations?
Everything was super straight forward except for the feasibility of Mars...
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http://www.wired.co.uk/article/nasa-rocket-fuel-mars
lucky i was reading this few days ago when i was procrastinating studding, haha
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Does anyone have a copy of the exam?
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http://www.wired.co.uk/article/nasa-rocket-fuel-mars
lucky i was reading this few days ago when i was procrastinating studding, haha
XD SAME!!!
But the exam only had 5 caculation short answers that was awkward
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Not much stoich :(. Most of it was pretty simple though except I thought mc wasn't great.
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what was the independent variable supposed to be for the titration experiment...? That was so confusing
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what was the independent variable supposed to be for the titration experiment...? That was so confusing
Ahh yes haha I had no idea, could have sworn they weren't changing anything lol
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I wrote down that it was the source of tartaric acid (from the commercial sample). It doesn't make any real sense to me, but at the time, it seemed like the best thing to write down.
I'm quite disappointed that there weren't many calculations. Multiple choice was a bit harder compared to last year's. The last MC, when it talked about which metal would deposit a greater amount than lead also befuddled me as well.
There seem to be a greater trend towards these writing/lengthy explanation questions. They did that for the Bio exam, and now, they're doing it for the Chem exam.
God knows what they'll do for Physics.
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Disappointing number of calculations, was expecting a less qualitative exam.
The first 8 short answers were pretty straight forward but I thought the last 2 were strange and troublesome. MCs weren't too bad.
Not sure if I should have spent 10 mins drawing the full structural formula of the triglyceride :P
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And we couldn’t even bring a dictionary, “feastabilily”
Feasibility
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I think question 9 was honestly to be expected. 10, ive never seen a question like that before on a chemistry exam. I. Frickin. Loved it. Which I realize might be a strange opinion, but come on, that was an interesting question, more fun than the constant need for the recitation of theory or calculations that were bombarding me prior to that question. I did, however, run out of time so i kind of rushed that question...
Also, for the independent variable, question 9, i chose the actual purity of the acid (though I think i said concentration, I actually meant purity). I realise the student isn't selecting values for it, but the way I saw it (and honestly this is very likely wrong), the value that is dependant on something else was the volume of the titre itself, and the variable that affects that would infact be the concentration. It also helps that the student was trying to figure out the purity of the commerical acid in the first place
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I think question 9 was honestly to be expected. 10, ive never seen a question like that before on a chemistry exam. I. Frickin. Loved it. Which I realize might be a strange opinion, but come on, that was an interesting question, more fun than the constant need for the recitation of theory or calculations that were bombarding me prior to that question. I did, however, run out of time so i kind of rushed that question...
Also, for the independent variable, question 9, i chose the actual purity of the acid (though I think i said concentration, I actually meant purity). I realise the student isn't selecting values for it, but the way I saw it (and honestly this is very likely wrong), the value that is dependant on something else was the volume of the titre itself, and the variable that affects that would infact be the concentration. It also helps that the student was trying to figure out the purity of the commerical acid in the first place
Agreed
An i think the Independent Variable was the amount of times the experiment was conducted before the concordant values were found sadly i didnt actually write that in the exam
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Hi what study score would an exam score of 117/120 with rank 1?
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Hi what study score would an exam score of 117/120 with rank 1?
48+
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Hi What study score 95/120 and 80 average in sacs - strong cohort
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What was the answer for the last multiple choice question? Also the PEM cell was weird........what was even the overall reaction? Has anyone put up any answers yet?
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Does anyone have a copy of the exam and solutions to the exam??
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What was the answer for the last multiple choice question? Also the PEM cell was weird........what was even the overall reaction? Has anyone put up any answers yet?
PEM cell was just a 02+2h2 ---> 2h20 reaction.
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I lost most of the marks for the experimental design and mars stuff.
It's not feasible to rely on low efficiency biofuels on mars due to the high expected population after vce students get their results.
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what was the independent variable supposed to be for the titration experiment...? That was so confusing
I reckon it was the volume of NaOH. That's what I put anyways, pretty sure I'm wrong.
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I lost most of the marks for the experimental design and mars stuff.
It's not feasible to rely on low efficiency biofuels on mars due to the high expected population after vce students get their results.
Witty.
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Would trial number be the independent variable?
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Would trial number be the independent variable?
I said the commercial acid....
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Shouldn’t the independent variable be the amount of powder form of the tartaric acid used ?
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Shouldn’t the independent variable be the amount of powder form of the tartaric acid used ?
genius.
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new study design how was it?
which past exam was it's difficulty comparable to?
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A copy of the exam?
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I reckon it was the volume of NaOH. That's what I put anyways, pretty sure I'm wrong.
I had the volume of NaOH as well. :/ since it was the only thing I noticed that changed :(
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Hi what study score would an exam score of 117/120 with rank 1?
50.
In 2013 I know of a 114.5/120 that got a 50.
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PEM cell was just a 02+2h2 ---> 2h20 reaction.
Thank goodness! That PEM question threw me off, but not as much as the last two questions.........Also what did everyone else get for the last multiple choice question?
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new study design how was it?
which past exam was it's difficulty comparable to?
Not really comparable directly to any I'd done, lots of theoretical stuff not much calculations. Overall not that hard to except a bit about travelling to mars and evaluating its 'feasibility', and some of m/c but that's more cos I didn't study until the weekend heh
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Yeah, most of the exams ive done thus far have been quite different from previous years (at least it felt so to me), chemistry was no exception
How about Rank 1 with about 105-110/120, what kind of range am I looking at there, anyone know?
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Yeah, most of the exams ive done thus far have been quite different from previous years (at least it felt so to me), chemistry was no exception
How about Rank 1 with about 105-110/120, what kind of range am I looking at there, anyone know?
I haven't seen the exam but around 42-45 from what I'm hearing about the exam :)
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Does anyone has Solutions of the exam?
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Is it just me was there an error in the question regarding the fluorine cell? It said something like 'water when in aqueous solution, becomes K+ and F-'.
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I reckon it was the volume of NaOH. That's what I put anyways, pretty sure I'm wrong.
I put that as well, that was the only thing I could think of
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I found the overall difficulty much harder than the sample.
There was so much more worded questions than usual.
Also, for the independent variable, I can’t remember what I wrote but thinking about it, the volume of NaOH could we possible. But then again, we aren’t technically changing this variable.
You could probably claim that the brand of the chemical used is the controlled variable, so it can’t the independent variable.
That mars question was fucking lame. VCAA should’ve had Q9 or Q10, not both. Way too time consuming.
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I found the overall difficulty much harder than the sample.
There was so much more worded questions than usual.
Also, for the independent variable, I can’t remember what I wrote but thinking about it, the volume of NaOH could we possible. But then again, we aren’t technically changing this variable.
You could probably claim that the brand of the chemical used is the controlled variable, so it can’t the independent variable.
That mars question was fucking lame. VCAA should’ve had Q9 or Q10, not both. Way too time consuming.
Yeah they usually only put one of those sort of questions, I was stressing out towards the end trying to read all that damn info about this moron's stupid titration
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The independent variable probably was the concentration of the NaOH since he controlled it by making up the solution to a specific amount. I put down 'the titrant used' so I'm not sure about that mark.
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I had the volume of of the tartartic acid as the independent variable - not to sure because volume of aliquot usually affects the amount of NaOH delivered?
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The independent variable probably was the concentration of the NaOH since he controlled it by making up the solution to a specific amount. I put down 'the titrant used' so I'm not sure about that mark.
That’s a controlled variable lol.
I think water angel is correct. The independent variable is probably the tartaric acid used. Completely overlooked that since they were all just 10mL...
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Hey guys,
what do u think a 95/120 and 80 percent sac average in a strong cohort will get
Thanks
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So how did everyone go about answering the Mars question?
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On question 1 short answer was the Alkene to alcohol reaction a hydration reaction?
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On question 1 short answer was the Alkene to alcohol reaction a hydration reaction?
Isn't it just addition because you break the double bond?
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Isn't it just addition because you break the double bond?
yeah I wrote addition
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Yeah you are 100% right I just wasn't thinking correctly
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On question 1 short answer was the Alkene to alcohol reaction a hydration reaction?
Hydration reaction should be right too imo
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What about hydrogenation ? D:
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What about hydrogenation ? D:
Hydrogenation reaction is a reaction with H2. So, unfortunately that's incorrect :/
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On question 1 short answer was the Alkene to alcohol reaction a hydration reaction?
I wrote down hydration, just to be sure.
I think addition or hydration should both be correct, but I don't know. Until we get the answers...
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anyone have answers please???
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what about hydrolysis instead of hydration
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what about hydrolysis instead of hydration
Hydrolysis breaks bonds to add in water, whilst hydration doesn't.
Again, not too sure.
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“feastabilily”
AHAHAHA "The Feastability of Mars." YUM. ::)
I wonder if it's made of cheese? Or is that the moon. :o 8)
...And that children, is where Mars bars come from.
We can even burn it under a can of water.
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AHAHAHA "The Feastability of Mars." YUM. ::)
I wonder if it's made of cheese? Or is that the moon. :o 8)
...And that children, is where Mars bars come from.
We can even burn it under a can of water.
Lmaoooooo
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yeah I wrote addition
i wrote addition too!
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i wrote addition too!
Me tooooooo :)
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Anyways.........THAT EXAM WAS AMAZING!!!!!
It was wayyyyyy easier than expected. However, those two stupid last questions didn't really need to be there. And oh my god I did so much practice on stoich ratios and calculations. ONLY ONE QUESTION on calculations. MC were really dry, probably the worst I've seen across any VCAA exam. But in all, not difficult at all! :P
Hope Physics and T&T are this good.
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Me tooooooo :)
I did addition as well, I mean surely they can't have wanted specifically hydration
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hey guys, i reckon it was a pretty good exam. problem is though -- i accidentally wrote in pencil.
can someone help me out here and tell me if my exam will still be marked? im currently freaking out rn because i feel like it was one of my best exams shittt
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hey guys, i reckon it was a pretty good exam. problem is though -- i accidentally wrote in pencil.
can someone help me out here and tell me if my exam will still be marked? im currently freaking out rn because i feel like it was one of my best exams shittt
Of course its marked... I know someone who did a whole exam in pencil and got 47 ssc, so dont worry
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I did addition as well, I mean surely they can't have wanted specifically hydration
I don't want to burst your bubble, but I'm pretty sure hydration was what they wanted, looking over my notes now.
Addition seems to general, but answers.... wait, WHERE ARE THE SOLUTIONS???
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hey guys, i reckon it was a pretty good exam. problem is though -- i accidentally wrote in pencil.
can someone help me out here and tell me if my exam will still be marked? im currently freaking out rn because i feel like it was one of my best exams shittt
the exam says to write only in pen but if you pressed hard enough then it should be able to be read, it's just that sometimes the heat rubs of the pencil when it gets scanned onto the computer
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where are the solutionsss
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Solutions anyone?!
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I don't want to burst your bubble, but I'm pretty sure hydration was what they wanted, looking over my notes now.
Addition seems too general, but answers.... wait, WHERE ARE THE SOLUTIONS???
Well bugger, there goes my 30
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Average 62% in SACS but our cohort is pretty strong
Think I got just over 55% in the Exam.
What Study Score do people recon that is?
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I don't want to burst your bubble, but I'm pretty sure hydration was what they wanted, looking over my notes now.
Addition seems to general, but answers.... wait, WHERE ARE THE SOLUTIONS???
Addition is not incorrect, I doubt it'd be marked wrong.
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Addition is not incorrect, I doubt it'd be marked wrong.
As mentioned before, I am not sure myself.
Solutions are still missing atm...
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As mentioned before, I am not sure myself.
Solutions are still missing atm...
Mind that suggested solutions do not necessarily reflect VCAA marking, so some additional things may be accepted if the assessors feel lenient.
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Mind that suggested solutions do not necessarily reflect VCAA marking, so some additional things may be accepted if the assessors feel lenient.
Naturally, given that the sample solutions that get released here aren't official afaik.
Still, it'd be good to see what others think so we can actually discuss the questions a bit further.
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is the solutions posted up yet?
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Are they up??
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Are they up??
The solutions will be up soon
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I don't want to burst your bubble, but I'm pretty sure hydration was what they wanted, looking over my notes now.
Addition seems to general, but answers.... wait, WHERE ARE THE SOLUTIONS???
pretty sure they'll accept addition... once they accepted 'covalent' for a question asking for the type of bond because even though it wasn't what they asked for it technically wasn't wrong... so i'm sure addition is accepted. same goes for ether/glycosidic link etc.
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Killed myself trying to understand calorimetry when none of it was there ?! The Mars question was an actual fuck up. At this point I'm hopping on board the submarine filled with that volatile H2
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where is the exam copy :(
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where is the exam copy :(
Copyright issues with matt damon atm soz
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Does spelling matter for the exams? Like if I spelt 'asphyxiation' as 'asphixiation', will I get the marks? Thanks
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Does spelling matter for the exams? Like if I spelt 'asphyxiation' as 'asphixiation', will I get the marks? Thanks
As long as it's understood you should get the marks, unless it's a total cooked spelling.
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I believe they did penalise misspellings of 'glycosidic' though.
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But like a non-VCE-chem word should be fine? Like asphyxiation? Cheers
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I reckon it was the volume of NaOH. That's what I put anyways, pretty sure I'm wrong.
The independent variable was the percentage purity of the tartaric acid, as that what was affecting the titre volume.
Whilst not being manipulated, it was neither controlled nor the dependent variable. The volume of NaOH was the dependent variable, the concentration of NaOH was controlled, and the volume of tartaric acid solution was also controlled.
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The independent variable was the percentage purity of the tartaric acid, as that what was affecting the titre volume.
Whilst not being manipulated, it was neither controlled nor the dependent variable. The volume of NaOH was the dependent variable, the concentration of NaOH was controlled, and the volume of tartaric acid solution was also controlled.
I think the concentration of tartaric acid was the independent variable since the percentage purity is not a variable in the experiment and just a result of calculations that require concentration of tartaric acid. The titre is not independent because it depends on concentration of tartaric acid
I hope that clarifies some issues.
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I think the concentration of tartaric acid was the independent variable since the percentage purity is not a variable in the experiment and just a result of calculations that require concentration of tartaric acid. The titre is not independent because it depends on concentration of tartaric acid
I hope that clarifies some issues.
If that's the case, how would one "control" or manipulate the concentration of tartaric acid? From what I can remember, the question stated that you had 30g of the commercial sample that was diluted to 500ml and then take aliquots from that.
Can you really say that you can manipulate the concentration when you don't even know how much the % of tartaric acid is even there in the first place? The only thing we know in relation is the manufacturer's claim on its purity.
I'd like to think the manipulated variable would have been the sample used, i.e. the tartaric acid sample itself, since we are testing the validity of the manufacturer's claim on the purity of the product.
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I'd like to think the manipulated variable would have been the sample used, i.e. the tartaric acid sample itself, since we are testing the validity of the manufacturer's claim on the purity of the product.
That's what I had, the SOURCE of the tartaric acid.
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Does anyone remember whether the answer to the multi choice question about the pH increase/decrease during recharge of a car battery was A or B. I’m scared I shaded the wrong bubble and put down a pH increase :(
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Does anyone remember whether the answer to the multi choice question about the pH increase/decrease during recharge of a car battery was A or B. I’m scared I shaded the wrong bubble and put down a pH increase :(
I put down decrease in pH and chemical energy converted into electrical energy.
Thinking back on it now, I think I may have gotten it wrong.
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I put down decrease in pH and chemical energy converted into electrical energy.
Thinking back on it now, I think I may have gotten it wrong.
I think it was a decrease in pH (because the concentration of H+ increases) and a conversion of electrical energy to chemical energy (as an external power source supplies electrical energy to reverse and "reset" the chemical reaction)
Hope this makes sense
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I think it was a decrease in pH (because the concentration of H+ increases) and a conversion of electrical energy to chemical energy (as an external power source supplies electrical energy to reverse and "reset" the chemical reaction)
Hope this makes sense
Ahhh, the external power source.
I forgot about that. Oh well.
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I think it was a decrease in pH (because the concentration of H+ increases) and a conversion of electrical energy to chemical energy (as an external power source supplies electrical energy to reverse and "reset" the chemical reaction)
Hope this makes sense
It was D right?
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Does anyone remember whether the answer to the multi choice question about the pH increase/decrease during recharge of a car battery was A or B. I’m scared I shaded the wrong bubble and put down a pH increase :(
The reaction given was the overall discharging reaction and H+ was a reactant meaning pH increases. However the question asks us what happens during discharge so H+ is a product hence ph decreases and since its recharging, conversion from electrical to chemical energy
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It was D right?
I think so yeah
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solutions up yet? :-\
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Doesn't seem like it.
Is there some issue with copyright, or was that just a joke?
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Doesn't seem like it.
Is there some issue with copyright, or was that just a joke?
More likely that its much harder for every day Joe's i.e. not VCAA assessors to write solutions for a very qualitative Chemistry exam when compared to something like Methods. In Maths theres one right answer and everything else is wrong, but for something like that Mars question it would be very difficult for someone outside of the official assessors to come up with an accurate marking scheme.
My advice - don't worry about it. Go to parties, sleep in. You can't change an exam you've already sat so imo theres no point thinking about it.
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Good advice.
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how about solutions for multi choice？
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So this is what I got:
1D 2A 3D 4B 5B 6C 7B 8A 9C 10D 11C 12A 13A 14D 15B 16A 17C 18B 19D 20D 21B 22C 23A 24C 25A 26A 27A 28C 29D 30B
but I have been known to make the odd mistake!
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More likely that its much harder for every day Joe's i.e. not VCAA assessors to write solutions for a very qualitative Chemistry exam when compared to something like Methods. In Maths theres one right answer and everything else is wrong, but for something like that Mars question it would be very difficult for someone outside of the official assessors to come up with an accurate marking scheme.
My advice - don't worry about it. Go to parties, sleep in. You can't change an exam you've already sat so imo theres no point thinking about it.
But is the actual exam even up? I can't find it anywhere?
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What did everyone get for the lithium battery question, 2nd one in multiple choice? I had no idea what the answer was. Can someone post the answer and explain why they got that
thanks :)
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for Q2 I got A as it showed the lowest temperatures and for a battery to be rechargeable the products need to stay in contact with the electrodes and this is most likely to happen when diffusion is minimised by low temperature. I couldn't see any other logic to use here
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for Q2 I got A as it showed the lowest temperatures and for a battery to be rechargeable the products need to stay in contact with the electrodes and this is most likely to happen when diffusion is minimised by low temperature. I couldn't see any other logic to use here
I see know! Thanks
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What did everyone get for the lithium battery question, 2nd one in multiple choice? I had no idea what the answer was. Can someone post the answer and explain why they got that
thanks :)
I got A as well just because it made sense that the biggest temperature difference would be the most suitable (witholds for longer) and there were two with the same difference but the other had a high temp range that isn't logical for phone use
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for Q2 I got A as it showed the lowest temperatures and for a battery to be rechargeable the products need to stay in contact with the electrodes and this is most likely to happen when diffusion is minimised by low temperature. I couldn't see any other logic to use here
Same, I thought that would slow the side reactions, but then I wasn't sure about the negative 8 degrees, would that be bad for the battery :/
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I'm not sure if I'm right but for the equilibrium constant I got something in the 80s my other mates got 0 point something. Can anyone clarify the right answer please????
81 point something?
If so, then don't worry. Pretty sure that's how you do it, as long as you remembered to convert the mol into M.
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81 point something?
If so, then don't worry. Pretty sure that's how you do it, as long as you remembered to convert the mol into M.
81.5 M^-1, im pretty sure
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What did people get for multiple choice 18, where it asks for the [NH3] following an increase in temperature?
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What did people get for multiple choice 18, where it asks for the [NH3] following an increase in temperature?
Increase in rate, decrease in concentration me thinks.
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What's your answer?
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Was your answer B?
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I think I got 20 something for the Kc. Isn't it 1.66^2/(((2-1.66)^2)*(2-1.66/2))?
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Seriously considering going to school to get my teacher's copy of the exam and scanning it up. It wont have answers, but it will be something.
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Could anyone remember what mc question 23 & 24 was on again? I can't really remember, not sure if my answers are correct. Also, did others also get 0.14 g for the caffeine question and 14.0% for the percentage of protein just to double check?
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Could anyone remember what mc question 23 & 24 was on again? I can't really remember, not sure if my answers are correct. Also, did others also get 0.14 g for the caffeine question and 14.0% for the percentage of protein just to double check?
23/24 was the HPLC stuff right? Or no?
I think I got A, which was 0.014...
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In relation to the battery question, the answer was B. I discussed with my teacher and we also discovered in the heineman textbook that low temperatures are not ideal for battery recharges. Negative 8 degrees Celsius is quite extreme for battery recharging ... also see this link for further validation, more specifically the paragraph labelled ‘Low-Temperature Charge’: http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures
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23/24 was the HPLC stuff right? Or no?
I think I got A, which was 0.014...
I don't know... cause I'm pretty sure that it was talking about mass in undiluted coffee of 350 mL, and the graph showed 0.04g/L when a 5 mL sample was diluted to 50mL, so I took into account of the dilution factor and multiplied concentration by 10?
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I think I got 20 something for the Kc. Isn't it 1.66^2/(((2-1.66)^2)*(2-1.66/2))?
Care the molar ratios
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I don't know... cause I'm pretty sure that it was talking about mass in undiluted coffee of 350 mL, and the graph showed 0.04g/L when a 5 mL sample was diluted to 50mL, so I took into account of the dilution factor and multiplied concentration by 10?
Now I don't even know what answer I wrote XD
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I think I got 20 something for the Kc. Isn't it 1.66^2/(((2-1.66)^2)*(2-1.66/2))?
No, you had to convert it to M, as they gave the question in mol
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Could anyone remember what mc question 23 & 24 was on again? I can't really remember, not sure if my answers are correct. Also, did others also get 0.14 g for the caffeine question and 14.0% for the percentage of protein just to double check?
the dietry fibres had to be excluded from the calculations, isnt that right?
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Oh of course; silly me.
I think I got 0·014g of caffeine and 14% of protein.
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the dietry fibres had to be excluded from the calculations, isnt that right?
Yeah - there was no data for energy that fibre provides anyway - only proteins, fats and carbs
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How hard is it to get a 35+ ssc in this subject, like roughly what exam score do you need? Anyone with experience or knowledge, not only me, many others will benefit from your reply
thanks :D
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Multi choice the most effective way for that vitamin C and D thingy, what did u guys put?
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In relation to the battery question, the answer was B. I discussed with my teacher and we also discovered in the heineman textbook that low temperatures are not ideal for battery recharges. Negative 8 degrees Celsius is quite extreme for battery recharging ... also see this link for further validation, more specifically the paragraph labelled ‘Low-Temperature Charge’:
http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures
I chose b as well as thas temperature wasn't as low as A but also wasn't as high and had the smallest difference between max and mix temp.
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Multi choice the most effective way for that vitamin C and D thingy, what did u guys put?
I think I put A (the one that said eat oranges and sit outside with sun protection) because you can't chemically dissolve a vitamin D tablet (since it's non-polar) in water like you can with a vitamin C tablet and drink it. That's just my logic behind it, could possibly be wrong though :)
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I think I put A (the one that said eat oranges and sit outside with sun protection) because you can't chemically dissolve a vitamin D tablet (since it's non-polar) in water like you can with a vitamin C tablet and drink it. That's just my logic behind it, could possibly be wrong though :)
I chose the supplement oils and the citrus fruits. Seems like everyone has their own opinion on this, lol.
I just chose the oils because I know that vitamin tablets aren't the most efficient or effective way of fixing deficiencies, and for being in the sun? Eh... even with sun protection, stay out for one hour... I don't know, really.
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The independent variable was the identity or brand of the tartaric acid sample.
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I chose the supplement oils and the citrus fruits. Seems like everyone has their own opinion on this, lol.
I just chose the oils because I know that vitamin tablets aren't the most efficient or effective way of fixing deficiencies, and for being in the sun? Eh... even with sun protection, stay out for one hour... I don't know, really.
Yeah I did the same!
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please anyone upload the paper
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Please
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please anyone upload the paper
Are you done with your exams? If yes go have fun, you aced it. if no you aced it and your gonna ace the coming one ;D ;D ;D ;D ;D ;D ;D ;D
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Yes, I chose A as well. Sitting outside in the sun is dangerous so not safe, and eating more leafy vegetables isn't going to fix you quickly if you have clinically low Vitamin C levels.
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Oh of course; silly me.
I think I got 0·014g of caffeine and 14% of protein.
which one was the protein question? i remember getting 13.2 percent for one Mcq question. Is that the one you're talking about?
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which one was the protein question? i remember getting 13.2 percent for one Mcq question. Is that the one you're talking about?
The dietary fibre is not digested so it is not considered in the energy intake that's why you get 14%. I got the same answer as you :P :P :-[ :-[
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The dietary fibre is not digested so it is not considered in the energy intake that's why you get 14%. I got the same answer as you :P :P :-[ :-[
omg, how were we supposed to know that!!!
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Hi all,
I am a chemistry teacher and my son did Chem this year. I am intrigued to have a look at this paper after all the comments from him and on here.
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Wait... there was nearly nothing on galvanic cells.
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Someone pleaseeeee upload the paper
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Someone go nag their chemistry teacher to photocopy it >:(
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Someone go nag their chemistry teacher to photocopy it >:(
I couldn't find it on their desk :(
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What do people think about the a plus cut off this year
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I'm supposed to be revising for a methods SAC but eh. Here it is:
Let the crying begin:
https://www.dropbox.com/s/lzgi4ofjn9rcwir/New%20Doc%2040%20%281%29.pdf?dl=0
Mod edit: Removed inappropriate comment.
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What did you guys put for 28 multi choice the redox one with the air present. I chose A, however I thought it was still wrong.
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Alright, now that we have an exam to work off of, solutions should slowly start to appear in the first post - keep your eyes peeled, and I'll make another post when every question has an answer. :) I don't have the time to go through the entire topic to check any contentions, so if you have one with of the suggested answers, post in here and a mod will change the front if need be and let you know if you're right or not.
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Lol already made 3 careless mistakes it seems..
I’m so dependent on excess time to look over my work to do well, it’s sad..
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My comments on the suggested MC answers are: (see page 7 for my choices)
Q2. What logic is used to arrive at C? the question is not asking for optimum operating conditions but for maximum number of recharges. This particular cell is not mandated in the study design and students do not have access to the internet while doing the exam.
Q3 I chose D as some definitions of zwitterion include no overall charge.
Q12 I thin k we are looking for the most unsaturated fatty acid here, so A
Q15. Sadly alcohol is actually toxic to cells. Alcohol lowers there polarity of the surrounding solution (from the usual watery environment) so Hydrogen bonding arrangement can change leading to denaturation. So B.
Q18. Increase in temp will increase both forward and back reaction rates and the forward reaction is exothermic co increase in temp will lead to a shift to reactants so a decrease in the conc of NH3 . B.
Q25. Amylopectin is more readily converted to glucose than amylose so it leads to a higher GI. The quest asks for lowest GI so we are looking for the highest amylose content which is A.
Q28 I found tricky but I chose C. because the lowest E0 reaction is still V2+ to V3+ but now as V3+ forms it could go on to be converted to VO2+ as the E0 for this is only +.34 so still low enough if the concentration of V3+ was high enough. I think B is unlikely as you are reversing an equation with the second highest E0 value given.
Q30. We need to consider charge as well as atomic mass here. The gold ion needs 3 electrons to make one atom whereas the silver ion needs only one. Use n=it/F to get the mole of e- used to plate the Pb then use the same moles of e- to work out the mass of each metal that will be plated, taking care of mole ratios, I think you get silver as the winner so B.
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Here are my suggested answers to the multi choice questions that keltingmeith has highlighted in their answers. Note that these are not anymore correct than the current solutions, they are my opinion only, so feel free to tell me where I'm wrong :)
3 D
I agree that D is the only reasonable answer, although the question can indeed be interpreted in different ways.
10 D
I'm pretty sure that zwitterions are by definition uncharged molecules (with internal charges), and I recall this being referenced somewhere in an examiner's report a few years ago.
13 A
C and D aren't correct (petrodiesel is neither renewable, nor does it have the lowest CO2 emissions). I'm saying A because it takes the least amount of fuel to travel the same distance as the other fuels.
15 B
Going from keltingmeith's response, I agree that C is not completely correct (since not all bonds are broken). I think that without the question specifically stating "denaturation of a protein in the body, B can be the correct answer.
16 A
This question seems to require some very detailed knowledge about the two vitamins (which is fair game, considering that it's in the study design and all :P). Vitamin D is not water-soluble, so C isn't correct. B is for vitamin D only, so isn't right either. D could be true (not actually sure if leafy vegetables are a good source of vitamin C), but "without wearing sun protection" seems to go against the "safely" term in the question.
19 D
B is not quantitative. I don't C is the answer, since viscosity would be the best point of comparison. D seems to be the best answer. Not sure if A is actually qualitative.
25 A
Lowest GI would imply it takes the longest to be digested and absorbed into the body. Amylose is less branched and compact than amylopectin, so low GI would imply high amylose.
My comments on the suggested MC answers are: (see page 7 for my choices)
Q2. What logic is used to arrive at C? the question is not asking for optimum operating conditions but for maximum number of recharges. This particular cell is not mandated in the study design and students do not have access to the internet while doing the exam.
Q3 I chose D as some definitions of zwitterion include no overall charge.
Q12 I thin k we are looking for the most unsaturated fatty acid here, so A
Q15. Sadly alcohol is actually toxic to cells. Alcohol lowers there polarity of the surrounding solution (from the usual watery environment) so Hydrogen bonding arrangement can change leading to denaturation. So B.
Q18. Increase in temp will increase both forward and back reaction rates and the forward reaction is exothermic co increase in temp will lead to a shift to reactants so a decrease in the conc of NH3 . A.
Q25. Amylopectin is more readily converted to glucose than amylose so it leads to a higher GI. The quest asks for lowest GI so we are looking for the highest amylose content which is A.
Q28 I found tricky but I chose C. because the lowest E0 reaction is still V2+ to V3+ but now as V3+ forms it could go on to be converted to VO2+ as the E0 for this is only +.34 so still low enough if the concentration of V3+ was high enough. I think B is unlikely as you are reversing an equation with the second highest E0 value given.
Q30. We need to consider charge as well as atomic mass here. The gold ion needs 3 electrons to make one atom whereas the silver ion needs only one. Use n=it/F to get the mole of e- used to plate the Pb then use the same moles of e- to work out the mass of each metal that will be plated, taking care of mole ratios, I think you get silver as the winner so B.
2) I think it should A be as well - since batteries have a longer life under colder conditions.
18) Do you mean B? :P
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Iv'e lost 5 marks on MC :(( what will be the cut off this year for A+ any predictions?
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Where is the answers, i cant access it
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Where is the answers, i cant access it
They're being added to the original (first) post
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I chose C for Q23 of MC, because I think taking samples from three sources will improve accuracy? Can someone explain why the answer is A?
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I chose C for Q23 of MC, because I think taking samples from three sources will improve accuracy? Can someone explain why the answer is A?
To take from different sources means you are not keeping the crude oil a constant variable. You may get variable results if you collect a sample from the tank of a truck, 500m underground, etc.
If you use a thermometer,
1) the accuracy is questionable if you're stirring one corner of the beaker
2) you may read it differently to somebody else
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Hi guys,
I have checked the both the mc answer short answer questions, but I need a bit more of checking with my answers to short answer questions.
For question 1, I did write H2O and MnO4/H+, but do we absolutely have to write states - I didn't for these? Like for the reaction between propanol and ethanoic acid, I wrote all of the reactants and products in liquid state? And also, do we have to absolutely include the H2SO4 catalyst for the formation of ester? (I forgot this) :(
For question 6ai, would it be okay for one mark to say that the electrolyte helps to carry ions between the electrodes so that they could react to form the products required?
For question 6bi, when it says 'state two advantages of PEM fuel cell', I mentioned that the fuel cell is more energy efficient compared to diesel engine, and also that it is more environmental friendly as no CO2 is produced. Would this be okay? (by the way, there is such thing as a closed system diesel engine in submarines)
For question 8d, when it says that why carbon anode cannot be interchanged with iron, I did say that iron is a stronger reducing agent and oxidises in preference to fl-, however, my half equation had the wrong state for Fe2+ cos I said that it was 'aq' instead of 'hf'. Would I get penalised for this?
For question 9b, would concentration of NaOH be an appropriate controlled variable - cause I said that higher concentrations of NaOH will result in less titre being delivered?
For question 9f, I wrote for preparing the solution you needed 'safety glasses, gloves and gas mask' and for conducting titration you needed 'safety glasses, gloves'. Would this be correct?
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What do u guys think about mcq 15. I thought it was C, whilst not all bonds are disrupted I thought it was a better option than alcohol, as we do digest and consume alcohol.
What do you guys also think a 100/120 and a 85 percent sac average in a strong cohort will get?
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@waterangel
Yes you would lose marks for wrong states, as mentioned in many examiners’ reports.
Yes the concentration of NaOH is one of the controlled variables in the experiment.
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What do u guys think about mcq 15. I thought it was C, whilst not all bonds are disrupted I thought it was a better option than alcohol, as we do digest and consume alcohol.
doesn't denaturation affect secondary and quaternary too? so the statement that all bonds are disrupted in tertiary is a bit vague
how did y'all interpret MCQ28?
I went with excess O2 means that O2 is always being reduced at the cathode
V(II) -> V(III) + e (-0.26V)
V(III) + H2O -> VO(II) + 2H + 2e (0.34V)
then theoretically VO(II) should keep oxidising to VO2(I) but theres no answer for that
So V(II) -> V(III) intermediate -> VO(II)
any thoughts?
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then theoretically VO(II) should keep oxidising to VO2(I) but theres no answer for that
my thoughts exactly. I got that far, then guessed the answer ::)
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On my phone plz forgive short responses, just ceebs. :P
My comments on the suggested MC answers are: (see page 7 for my choices)
Q2. What logic is used to arrive at C? the question is not asking for optimum operating conditions but for maximum number of recharges. This particular cell is not mandated in the study design and students do not have access to the internet while doing the exam.
Q3 I chose D as some definitions of zwitterion include no overall charge.
Q12 I thin k we are looking for the most unsaturated fatty acid here, so A
Q15. Sadly alcohol is actually toxic to cells. Alcohol lowers there polarity of the surrounding solution (from the usual watery environment) so Hydrogen bonding arrangement can change leading to denaturation. So B.
Q18. Increase in temp will increase both forward and back reaction rates and the forward reaction is exothermic co increase in temp will lead to a shift to reactants so a decrease in the conc of NH3 . A.
Q25. Amylopectin is more readily converted to glucose than amylose so it leads to a higher GI. The quest asks for lowest GI so we are looking for the highest amylose content which is A.
Q28 I found tricky but I chose C. because the lowest E0 reaction is still V2+ to V3+ but now as V3+ forms it could go on to be converted to VO2+ as the E0 for this is only +.34 so still low enough if the concentration of V3+ was high enough. I think B is unlikely as you are reversing an equation with the second highest E0 value given.
Q30. We need to consider charge as well as atomic mass here. The gold ion needs 3 electrons to make one atom whereas the silver ion needs only one. Use n=it/F to get the mole of e- used to plate the Pb then use the same moles of e- to work out the mass of each metal that will be plated, taking care of mole ratios, I think you get silver as the winner so B.
2. Chose that using the logic that those temperatures are more likely to mimic everyday life. If you think there's something being taught that would better apply to this question than my simple logic, more than happy to change the answer.
12. I'm actually fairly confident here - they're all the same length, so more saturation = more spots to oxidise, hence my decision to pick the most saturated.
15. Yeah, it was close between the two. The only thing is enzymes typically exist in water, with alcohols being a weaker hydrogen bond donor and acceptor, so I kinda can't see how they'd compete with the water for interactions with the protein? Unless I'm thinking about it the wrong way, but I'm assuming in the body and they might be implying a benchtop environment.
18. Loooool can you tell it was like 1 in the morning when I did this? Changing to B.
25. Cool, I figured amylopectin is absorbed faster, I must've interpreted GI itself wrong, hence having the exact opposite answer. :P will change
28. Yeah, I didn't like picking B for that reason. I do like your logic for C though, will change.
30. Reckon you could step through those calcs? Because I tried to go pure logic (you don't want to know how long it's been since I've done this kind of electrochem, it's the reason I don't tutor VCE), and that logic says gold should still return more mass than silver.
Here are my suggested answers to the multi choice questions that keltingmeith has highlighted in their answers. Note that these are not anymore correct than the current solutions, they are my opinion only, so feel free to tell me where I'm wrong :)
3 D
I agree that D is the only reasonable answer, although the question can indeed be interpreted in different ways.
10 D
I'm pretty sure that zwitterions are by definition uncharged molecules (with internal charges), and I recall this being referenced somewhere in an examiner's report a few years ago.
13 A
C and D aren't correct (petrodiesel is neither renewable, nor does it have the lowest CO2 emissions). I'm saying A because it takes the least amount of fuel to travel the same distance as the other fuels.
15 B
Going from keltingmeith's response, I agree that C is not completely correct (since not all bonds are broken). I think that without the question specifically stating "denaturation of a protein in the body, B can be the correct answer.
16 A
This question seems to require some very detailed knowledge about the two vitamins (which is fair game, considering that it's in the study design and all :P). Vitamin D is not water-soluble, so C isn't correct. B is for vitamin D only, so isn't right either. D could be true (not actually sure if leafy vegetables are a good source of vitamin C), but "without wearing sun protection" seems to go against the "safely" term in the question.
19 D
B is not quantitative. I don't C is the answer, since viscosity would be the best point of comparison. D seems to be the best answer. Not sure if A is actually qualitative.
25 A
Lowest GI would imply it takes the longest to be digested and absorbed into the body. Amylose is less branched and compact than amylopectin, so low GI would imply high amylose.
10. Sweet, I preferred D, anyway. More than happy to go off of an examiner's report.
13. Glad some of my logic is good. :')
15. Another B rooter. I might change that one, then. Still seems weird to me, but I'm not a big protein chemist, so. :S
16. Wow. The study design really has changed...
I chose C for Q23 of MC, because I think taking samples from three sources will improve accuracy? Can someone explain why the answer is A?
Not a fan of bentennason's logic here - however, C isn't true in the sense that sampling from different places isn't going to improve accuracy. It'll give you a measure of precision. It's not a bad idea, you're right, it just won't improve accuracy.
Meanwhile, the thermometer will definitely improve precision, hence the choice for that.
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Thanks to everyone checking my answers - keep them coming if you have concerns about something I've written. :)
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I think that question 2 in MC should be B - its the lowest temp range above freezing point. I think, as its an lithium ion battery, they're implying the presence of water, so it has to be above freezing point to function, but other then that I think the lowest possible temp will decrease the rate of unwanted reaction in the battery. Thats just my two cents, I'm reasonably certain my teacher said we didn't have to know about specific batteries anymore...
EDIT: here's a page I found. Not sure about its validity, but it seems to support what I'm saying:
https://arstechnica.com/gadgets/2011/02/ask-ars-what-is-the-best-way-to-use-an-li-ion-battery/
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Hi guys,
I have checked the both the mc answer short answer questions, but I need a bit more of checking with my answers to short answer questions.
For question 1, I did write H2O and MnO4/H+, but do we absolutely have to write states - I didn't for these? Like for the reaction between propanol and ethanoic acid, I wrote all of the reactants and products in liquid state? And also, do we have to absolutely include the H2SO4 catalyst for the formation of ester? (I forgot this) :(
For question 6ai, would it be okay for one mark to say that the electrolyte helps to carry ions between the electrodes so that they could react to form the products required?
For question 6bi, when it says 'state two advantages of PEM fuel cell', I mentioned that the fuel cell is more energy efficient compared to diesel engine, and also that it is more environmental friendly as no CO2 is produced. Would this be okay? (by the way, there is such thing as a closed system diesel engine in submarines)
For question 8d, when it says that why carbon anode cannot be interchanged with iron, I did say that iron is a stronger reducing agent and oxidises in preference to fl-, however, my half equation had the wrong state for Fe2+ cos I said that it was 'aq' instead of 'hf'. Would I get penalised for this?
For question 9b, would concentration of NaOH be an appropriate controlled variable - cause I said that higher concentrations of NaOH will result in less titre being delivered?
For question 9f, I wrote for preparing the solution you needed 'safety glasses, gloves and gas mask' and for conducting titration you needed 'safety glasses, gloves'. Would this be correct?
6ai) seems ok albeit not mentioning "hydrogen ions" as in this case you do know ion's identity
6bi) not sure if there is a context behind the question, ie. you don't want to be detected while underwater, don't want to pollute the local environment with CO2...
if there is context, i reckon both your CO2 argument and efficiency are valid; the unreacted gas looks like it can be pooled again.
9b) a good point. although if you literally use a more concentrated solution of NaOH (ie. using 0.55M vs 0.50M), the result will not change. your argument only applies if you're thinking you're using 0.50M, but in actual fact it is 0.55M. depends on wording
9f) what about a lab coat? we doin this in boxers, flip flops and a singlet? :D edit: luckily i didn't sit this exam
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It said excepting a lab coat.
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Question 10 is D. Zwitterions by definition are uncharged overall.
Also, question 15 is B. Alcohol does disrupt hydrogen bonding.
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I think that question 2 in MC should be B - its the lowest temp range above freezing point. I think, as its an lithium ion battery, they're implying the presence of water, so it has to be above freezing point to function, but other then that I think the lowest possible temp will decrease the rate of unwanted reaction in the battery. Thats just my two cents, I'm reasonably certain my teacher said we didn't have to know about specific batteries anymore...
EDIT: here's a page I found. Not sure about its validity, but it seems to support what I'm saying:
https://arstechnica.com/gadgets/2011/02/ask-ars-what-is-the-best-way-to-use-an-li-ion-battery/
Lithium ion batteries don't contain water; if they did, the battery would explode since Li and H2O react violently to form H2.
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Does anyone have any sample solutions for short answer? I know some are quite open so obviously are not a proper guide as to what VCAA will mark as correct but just want an idea of what should have been said
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Does anyone have any sample solutions for short answer? I know some are quite open so obviously are not a proper guide as to what VCAA will mark as correct but just want an idea of what should have been said
Working on it, sorry. Had important meetings today I had to deal with, then had to help my mum with her computer (who is so bad with them she had to make a shortcut to her desktop).
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Working on it, sorry. Had important meetings today I had to deal with, then had to help my mum with her computer (who is so bad with them she had to make a shortcut to her desktop).
No need to apologise! Not something anyone is obliged to in anyway. Sorry if that was a bit impatient or demanding sounding, I just have a tendency to overthink things and convince myself that I fail everything lol... and then I wonder why I don’t sleep. Seriously though, no rush - you guys don’t HAVE to do this all for us and have other things that need to be done before writing up solutions for anxious year 12s. I can imagine these would be a bit time consuming too as there are various answers for some questions, especially the last 2. Thank you for taking the time to do them :)
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But could Q23 of MC be indicating that by sampling from different sources, accuracy could be improved? Which means that the sampling bias is minimized so that the experimental value is closer to the true value? Can someone help me out?
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But could Q23 of MC be indicating that by sampling from different sources, accuracy could be improved? Which means that the sampling bias is minimized so that the experimental value is closer to the true value? Can someone help me out?
But it wouldn't improve accuracy, it would improve precision. If there is a sampling bias, as each sample is collected in the same way, the bias would exist in each, still.
It is inherently a good idea to collect from multiple samples - but to increase precision. You can't improve accuracy except by taking extra care with sample prep, and that's why C isn't the right answer - not because taking multiple samples is a bad idea, but because it won't improve accuracy, which is what the answer says it does.
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Thanks for the reply! But I thought increasing the sample size improve precision, whereas limiting sampling bias improve accuracy... Or am I so wrong...
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Thanks for the reply! But I thought increasing the sample size improve precision, whereas limiting sampling bias improve accuracy... Or am I so wrong...
Limiting sampling bias does improve accuracy, but sampling from multiple places isn't going to decrease sampling bias, it's going to increase the sample size.
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can someone plz post the solutions. been waiting for agess :( :(
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can someone plz post the solutions. been waiting for agess :( :(
There's some solutions to the MCQ in the first post (a couple of them need to change), I'll be working on the short-answer questions tonight.
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can someone plz post the solutions. been waiting for agess :( :(
Please remember that the kind people who use their time to write solutions are volunteers
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Q 20/21:
(Sorry for the poor quality, I couldn't be bothered using the software thing):
https://www.dropbox.com/home/Work?preview=20171206_232259.jpg