ATAR Notes: Forum
Archived Discussion => VCE Exam Discussion 2020 => Exam Discussion => Victoria => Science Exams => Topic started by: AAGlue on November 23, 2020, 12:12:08 pm
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How did everyone find it? :D
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It was ok - very long tho, almost didn't finish it
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Not that hard, but not easy. MCQ was definitely tricky imo and caused me to waste time. Didnt even finish the last question... oh well, at least it is over.
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Did anyone find the MC really difficult?...
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It was ok - very long tho, almost didn't finish it
SAME, I was panicking because those worded responses were taking a billion years to write
Not that hard, but not easy. MCQ was definitely tricky imo and caused me to waste time. Didnt even finish the last question... oh well, at least it is over.
Yea it was much harder than last years.
What did everyone get for the calibration temperature-time graph MCQ (forgot the number)?
I put down B but I was so confused
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I thought the exam was lovely! Keep in mind I’m DEFINITLEY not getting a 40 study score so I probably failed. Maybe I’m just blinded by the fact it was my last VCE exam!
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It was ok, a couple of tricky questions though
Ran out of time on the last question :( only had about a sentence left to write
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I finished writing in the last second lol. It was long....lots of worded questions. I got through it solidly but idk.
MC was quite difficult - had to guess a few!!
Idk I think I did okay ish - hopefully my worded responses had enough detail. I do think it was harder than last years. Probs will be a similar cut off to last years.
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What did you guys get for the percentage heat loss to the environment question?
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What did you guys get for the percentage heat loss to the environment question?
33%
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33%
omg yay, i got that too. i was tossing up between 33 and 50
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How many minutes did you guys get for that 58% efficeny question?
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How many minutes did you guys get for that 58% efficeny question?
37?
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37?
dam i got 31
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How many ripe bananas did the runner need to consume? I got 0.66.
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yeah, 0.66 seems correct
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How many ripe bananas did the runner need to consume? I got 0.66.
Same. it was less than 1 and I reckoned that was why they asked for 2 decimal places
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37?
I got 12 lol :P
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How many ripe bananas did the runner need to consume? I got 0.66.
I got 0.73, because I took away dietary fibre from the carbohydrates, but honestly that was a sh** question because it wasnt clear if fibre was included or not
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Sorry I wasn't online to help you all on the lead-up to this! But it sounds like you all have done fairly well. Wish I could provide clarity on questions, but I don't have a copy of the exam, sorry :(
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37?
37 is correct!
I accidentally put 52% into my calculator and got it wrong :(
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What did you guys talk about for the second last question when it asked about qualitative analysis of alcohols etc..?
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What did you guys talk about for the second last question when it asked about qualitative analysis of alcohols etc..?
I talked about like doing some tests with carboxylic acids to see if esters would form and give off smell, and talked about the tests you can conduct for primary/secondary/tertiary alcohols. not gonna lie had no clue if I am getting any marks just tried to write smth for the sake of writing it ahha. Quantitative I just said titrations ran out of time
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37 is correct!
I accidentally put 52% into my calculator and got it wrong :(
wait why is it not 12
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I got 0.73, because I took away dietary fibre from the carbohydrates, but honestly that was a sh** question because it wasnt clear if fibre was included or not
dietary fibres are cellulose tho, which can't be digested - I'm not sure tho I'm pretty bad at chem and our teachers are sketchy lol
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33%
I got 33% aswell, I think thats correct... unless
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37?
yes me too!
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wait why is it not 12
I did the calculation again straight after the exam but could not remember much about it... was it something about the ratio of electrons, like 2 to 12?
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Noooo, I just realised that I left my answer in seconds! Does anyone remember how much marks this Q was out of? :'( I think if I converted my answer to minutes I would have gotten around 12 minutes too.
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Noooo, I just realised that I left my answer in seconds! Does anyone remember how much marks this Q was out of? :'( I think if I converted my answer to minutes I would have gotten around 12 minutes too.
It was out of 3 marks if I remember correctly, and I think the answer is 37 minutes (I may be wrong).
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It was out of 3 marks if I remember correctly, and I think the answer is 37 minutes (I may be wrong).
Yep, 37 minutes
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Yep, 37 minutes
Yesss, 37 minutes!
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What did you guys get for the analysis of the organic compound with C4H8O but non cyclic and contained double bonds... was it an ether molecule with carbon to carbon double you had to draw I couldn’t find any peak for aldehyde or ketones 🥴😬
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What did you guys get for the analysis of the organic compound with C4H8O but non cyclic and contained double bonds... was it an ether molecule with carbon to carbon double you had to draw I couldn’t find any peak for aldehyde or ketones 🥴😬
ohhhhh I thought it was C=O double bond and drew a ketone and an aldehyde
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ohhhhh I thought it was C=O double bond and drew a ketone and an aldehyde
I drew a ketone and an aldehyde as well lol.
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Yeah i drew two ethers...
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For the question, i think it was a question where the solution was not aqueous and it asked to write the overall equation. Did you guys include states in it? I didn't know what states to put since it said it wasn't aqueous...
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If that was the redox question without given states, I just ignored it. 90% chance it won't be the states question since it was only worth a mark
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If that was the redox question without given states, I just ignored it. 90% chance it won't be the states question since it was only worth a mark
Ok thanks I ignored the states as well. :)
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dietary fibres are cellulose tho, which can't be digested - I'm not sure tho I'm pretty bad at chem and our teachers are sketchy lol
No I got 0.73 bananas, because there’s less carbs, and cuz the energy value is smaller when you take away the fibre you need more bananas to get the 300 Kj
Wow what did I just write omg lol
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I drew a ketone and an aldehyde as well lol.
I did the same, there was a peak at around 1600-1700, so I just assumed it would be so..
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What did everyone say for the “what information from the HNMR a and how it can help you decide what the structure is”
You has to make 3 points but it was my last question so idk what even happened (I did Q9 &10 first)
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What did everyone say for the “what information from the HNMR a and how it can help you decide what the structure is”
You has to make 3 points but it was my last question so idk what even happened (I did Q9 &10 first)
1) number of environments - 3
2) relative areas = number of H - 3:2:2
3) 1 of the chemical shifts corresponding to an environment - I wrote 3.85 ppm was a R-CH3-CO smth like that
Then I just linked it to something about the structure
Imo it should have been like a 6 mark Q and there should have been more lines to write in :-[
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1) number of environments - 3
2) relative areas = number of H - 3:2:2
3) 1 of the chemical shifts corresponding to an environment - I wrote 3.85 ppm was a R-CH3-CO smth like that
Then I just linked it to something about the structure
Imo it should have been like a 6 mark Q and there should have been more lines to write in :-[
Yeah since there was no space I wasn’t specific to the question about C4H.....oops :( I could barely fit explaining what that is AND how it helps to decide. 0/3 marks for me VCAA have mercy :(
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What did you guys say when it asked to talk about comparing methane obtained from landfill compared to natural gas?
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Yeah since there was no space I wasn’t specific to the question about C4H.....oops :( I could barely fit explaining what that is AND how it helps to decide. 0/3 marks for me VCAA have mercy :(
This is how VCAA makes exams hard :(
You don’t get marks because of bad formatting lol
I think you’ll get at least 1 mark though for writing something tho
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What did you guys say when it asked to talk about comparing methane obtained from landfill compared to natural gas?
Landfill - positive impact, burning CH4 into CO2 minimises impact of CH4 that was going to be released anyway from the landfill since CH4 is a more potent greenhouse gas than CO2
Natural gas - non-renewable fossil fuel -> exacerbates climate change
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No I got 0.73 bananas, because there’s less carbs, and cuz the energy value is smaller when you take away the fibre you need more bananas to get the 300 Kj
Wow what did I just write omg lol
Ok sorry gotcha now - wow that's really confusing actually
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Ok sorry gotcha now - wow that's really confusing actually
Tbh they should put dietary fibre as a subgroup under carbohydrates, literally no one separates them in real life
VCAA put so many bad Qs in the exam today lol
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In multiple choice, question 2, what did a larger sample size in an experiment improve? Validity, reliability, precision or uncertainty?
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In multiple choice, question 2, what did a larger sample size in an experiment improve? Validity, reliability, precision or uncertainty?
reliability I reckon
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reliability I reckon
I said validity... I feel like I'm right tho?
I think it would be reliability
Cuz even if you increase the sample space if the method sucks it still would be invalid
Reliability is like consistency so if you get more (precise) results that fit within the range you can say its more reliable
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Rip. What other hard MC's were there
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In multiple choice, question 2, what did a larger sample size in an experiment improve? Validity, reliability, precision or uncertainty?
This is an interesting one - I would say that the correct answer is uncertainty, and here's why:
1. A larger sample size can improve validity - but if your larger selection still has the same sampling bias as your smaller sample size, then the experiment is just as invalid.
2. Reliability. See above. If you're still sampling the wrong kind of people, your results are just unreliable
3. Precision, is where it gets interesting... You see, in some sense, precision and uncertainty go hand in hand. I've opted for precision to be incorrect because past, individual experiments can be just as imprecise.
4. Uncertainty, however, is kind of an average of the precision - and uncertainty HAS to go down if you increase the number of experiments, even if the new tests are just as imprecise as the previous ones, because that's the nature of uncertainty - repeat results give you more confidence for them to keep repeating.
But this is a tricky one, and I wouldn't be surprised if VCAA has a different stance - I could reasonably see all of these being improved by an increase in sample size, so we'll just have to wait and see what VCAA says. And who knows, maybe they'll decide in hindsight that this was too ambiguous, and give multiple answers a mark (this has been done in the past, though I don't remember the exact question - just that it was in my specialist exam, back when I took the subject)
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This is an interesting one - I would say that the correct answer is uncertainty, and here's why:
1. A larger sample size can improve validity - but if your larger selection still has the same sampling bias as your smaller sample size, then the experiment is just as invalid.
2. Reliability. See above. If you're still sampling the wrong kind of people, your results are just unreliable
3. Precision, is where it gets interesting... You see, in some sense, precision and uncertainty go hand in hand. I've opted for precision to be incorrect because past, individual experiments can be just as imprecise.
4. Uncertainty, however, is kind of an average of the precision - and uncertainty HAS to go down if you increase the number of experiments, even if the new tests are just as imprecise as the previous ones, because that's the nature of uncertainty - repeat results give you more confidence for them to keep repeating.
But this is a tricky one, and I wouldn't be surprised if VCAA has a different stance - I could reasonably see all of these being improved by an increase in sample size, so we'll just have to wait and see what VCAA says. And who knows, maybe they'll decide in hindsight that this was too ambiguous, and give multiple answers a mark (this has been done in the past, though I don't remember the exact question - just that it was in my specialist exam, back when I took the subject)
But tbh we didn’t even learn uncertainty in class lol
U4 AOS 3 was a complete mess : D
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But tbh we didn’t even learn uncertainty in class lol
U4 AOS 3 was a complete mess : D
I can imagine - and again, add that to a question that I would call ambiguous at best in the first place, I would not feel bad if you lost this one mark, and take solace in knowing they might allow multiple answers, anyway.
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I can imagine - and again, add that to a question that I would call ambiguous at best in the first place, I would not feel bad if you lost this one mark, and take solace in knowing they might allow multiple answers, anyway.
Thank god, the MCQ this year was literally cursed ;)
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33%
Might be just me but the delta T was 32.3-20 so I rounded it to 12 and got 35%. Would that be correct? (Considering that’s how significant figures work)
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This is an interesting one - I would say that the correct answer is uncertainty, and here's why:
1. A larger sample size can improve validity - but if your larger selection still has the same sampling bias as your smaller sample size, then the experiment is just as invalid.
2. Reliability. See above. If you're still sampling the wrong kind of people, your results are just unreliable
3. Precision, is where it gets interesting... You see, in some sense, precision and uncertainty go hand in hand. I've opted for precision to be incorrect because past, individual experiments can be just as imprecise.
4. Uncertainty, however, is kind of an average of the precision - and uncertainty HAS to go down if you increase the number of experiments, even if the new tests are just as imprecise as the previous ones, because that's the nature of uncertainty - repeat results give you more confidence for them to keep repeating.
But this is a tricky one, and I wouldn't be surprised if VCAA has a different stance - I could reasonably see all of these being improved by an increase in sample size, so we'll just have to wait and see what VCAA says. And who knows, maybe they'll decide in hindsight that this was too ambiguous, and give multiple answers a mark (this has been done in the past, though I don't remember the exact question - just that it was in my specialist exam, back when I took the subject)
I'm pretty sure the question asked which of the four would increase with a larger sample size. Uncertainty would decrease with a larger sample, so I don't think that was the correct option. The wording may be important. Reliability seems like the right one.
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I'm pretty sure the question asked which of the four would increase with a larger sample size. Uncertainty would decrease with a larger sample, so I don't think that was the correct option. The wording may be important. Reliability seems like the right one.
Yep I think that was how it was worded
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Surely someones got answers for the mc?
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Might be just me but the delta T was 32.3-20 so I rounded it to 12 and got 35%. Would that be correct? (Considering that’s how significant figures work)
You are only supposed to round your final answer to the correct significant figures. So, given if 33% is the correct answer, i don’t think vcaa will accept 35% but i think you will get marks for your working out :)
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You are only supposed to round your final answer to the correct significant figures. So, given if 33% is the correct answer, i don’t think vcaa will accept 35% but i think you will get marks for your working out :)
ooooft hopefully 2/3 then. I must have mixed up the rules lol
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Surely someones got answers for the mc?
DACDB
DBDBC
CDCAB
AACBB
CAADB
BACBC
These are my answers. quite UNSURE, especially for 10 and 28
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DACDB
DBDBC
CDCAB
AACBB
CAADB
BACBC
These are my answers. quite UNSURE, especially for 10 and 28
Do you have a copy of the actual questions because I can't really remember them
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Do you have a copy of the actual questions because I can't really remember them
https://mp.weixin.qq.com/s/e8WwrED428ZGyTiJisOLdQ
hopefully it can be opened
don't care about the answers they provided :)
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https://mp.weixin.qq.com/s/e8WwrED428ZGyTiJisOLdQ
hopefully it can be opened
don't care about the answers they provided :)
SHouldn't question 19 be C?
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SHouldn't question 19 be C?
Yup. It should. I think some of their mcq are incorrect.
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https://mp.weixin.qq.com/s/e8WwrED428ZGyTiJisOLdQ
hopefully it can be opened
don't care about the answers they provided :)
Hi - thanks for posting the answers, however, is it just me or a few of the answers are kind of dodgy?
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Hi - thanks for posting the answers, however, is it just me or a few of the answers are kind of dodgy?
I don't think they got all the answers correct as well :) so don't worry
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SHouldn't question 19 be C?
oh that would be the other one that I was unsure about. I was thinking that the backward reaction had a greater instant change than the forward one, then gradually decreased until equilibrium
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and isnt 17 A?
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and isnt 17 A?
17 is most definitely A.
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I'm pretty sure the question asked which of the four would increase with a larger sample size. Uncertainty would decrease with a larger sample, so I don't think that was the correct option. The wording may be important. Reliability seems like the right one.
You're absolutely right - and looking at the question now, uncertainty cannot be right, because it MUST DECREASE if you increase sample size. I'm a little unsure if it would be reliability or precision looking at this, but I do agree, reliability seems slightly more correct.
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I would like to go through the whole booklet and at least tell you all which MCQs I agree with, unfortunately I don't have that kind of time :S So instead, I'll keep an eye on this thread, and clarify any confusions of their answers and let people know if I agree with them and explain why they're right, or let you know if I think they're wrong as well. With that in mind:
and isnt 17 A?
Yeah, as AE said, 17 should be A. I'm guess they accidentally read volume as pressure, because an increase in pressure would have the exact same effect.
SHouldn't question 19 be C?
o boy, disagreements! I agree with the answer booklet.
Remember, the y-axis says rate, not concentration. It doesn't matter whether it says rate of forward reaction, or rate of backwards reaction - because at equilibrium, the rate of the forwards and backwards reactions are equal. So, if the rate has increased, and it's because of a temperature change, the temperature HAS to have gone up. In an exothermic reaction, increase temperature = shift to left, so the solution would get darker.
Thus, the answer to 19 is B, as indicated
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For question 6 I put B? the half cells for electrolytic threw me off :-\
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Hi
can someone please tell me
what were we meant to write for the equilibrium question,
for effect on temperature and pressure
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Hi
can someone please tell me
what were we meant to write for the equilibrium question,
for effect on temperature and pressure
I wrote about the effect of the increase and decrease of temperature and pressure on the yield of the product and you had to do this by referring to Le Chatelier's principle. So basically acknowledging that the system is exothermic and how it will partially oppose the changes of an increase/decrease of temperature and pressure.
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https://mp.weixin.qq.com/s/e8WwrED428ZGyTiJisOLdQ
hopefully it can be opened
don't care about the answers they provided :)
hi with these answers, what did people write for SAQ 4)d? they haven't written anything for this
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I wrote about the effect of the increase and decrease of temperature and pressure on the yield of the product and you had to do this by referring to Le Chatelier's principle. So basically acknowledging that the system is exothermic and how it will partially oppose the changes of an increase/decrease of temperature and pressure.
Thank you,
i acknowledged that it was exothermic and only wrote about the effect on the increase in temperature. and with pressure i said if it is increased and how it is opposed by LCP
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also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?
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For question 6 I put B? the half cells for electrolytic threw me off :-\
Must preface this with an apology - electrochem is not my best area!
When they say half-cell, it doesn't just mean the electrodes. It also means the components of each half-cell, such as the electrolyte, the rest of the environment, etc. And, it is true that the products MUST depend on all of those things, otherwise you're making something out of nothing. And, chemical energy->electrical energy is the whole point of a galvanic cell, hence why D is correct.
As for B - it is wrong because the electrolyte concentration can and will affect the amount of energy that comes out. You've learned how to calculate the energy for a Galvanic cell purely for a cell in standard conditions - 25 degrees C, 1 atm of pressure, and with concentrations of all components of 0.1 M. Things become more complicated when ANY of those things change.
hi with these answers, what did people write for SAQ 4)d? they haven't written anything for this
I think you could accept yes or no with the right reasoning, but I imagine that they want you to say it can, because more moles of CO2 are used than are produced.
also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?
Yes, you should.
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also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?
I think this is the correct answer. It doesn’t make sense to have a triglyceride with 62 H molecules since you have C16H30O2 * 3 + C3H8O3 - 3 H2O
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I think this is the correct answer. It doesn’t make sense to have a triglyceride with 62 H molecules since you have C16H30O2 * 3 + C3H8O3 - 3 H2O
yeah it should be 800. The answer is wrong there. 92 H not 62
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woah thank you keltingmeith for your explanation!! that would make sense, i never really considered non SLC.
also thanks fwift52 and zoharreznik :PP im so relieved i got that right i spent way too long on it
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What were the 2 different ways to present the results in the short answer question for the effect of temperature on the rate of reaction question?
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What were the 2 different ways to present the results in the short answer question for the effect of temperature on the rate of reaction question?
IV on the x axis and DV on the y axis, as well as drawing a best line of fit (rather than connecting each individual point).
I did the first, but instead of the second i talked about having a better title that actually presents the relationship between the IV and DV, but not sure if that would work
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For the question of why the aqueous solution was unsafe, i wrote water is a stronger oxidant than iodine ion and so would be reduced in preference producing Hydrogen gas. Would this be correct?
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For the question of why the aqueous solution was unsafe, i wrote water is a stronger oxidant than iodine ion and so would be reduced in preference producing Hydrogen gas. Would this be correct?
Which question was this?
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Which question was this?
It was the lithium carbon dioxide electrolytic cell question
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It was the lithium carbon dioxide electrolytic cell question
Yeah - so, the hydrogen gas one could be something they accept, and the tutoring agency that shared their answers wrote that as well. For me, the first thing I notice is that there's so much lithium around. Lots and lots and lots of lithium, which is an alkali metal. Pretty much any alkali metal + water = highly exothermic reaction, which is the big thing that I'd be cautious of. Presumably - they accept both.
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Yeah - so, the hydrogen gas one could be something they accept, and the tutoring agency that shared their answers wrote that as well. For me, the first thing I notice is that there's so much lithium around. Lots and lots and lots of lithium, which is an alkali metal. Pretty much any alkali metal + water = highly exothermic reaction, which is the big thing that I'd be cautious of. Presumably - they accept both.
it was a three mark question, so what would the marks generally be located for? Because I feel like there wasn't too much to explain in this question
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it was a three mark question, so what would the marks generally be located for? Because I feel like there wasn't too much to explain in this question
Yeah, good question, I missed that. Since they mentioned you should use an equation, you 100% need to list the lithium hydrolysis equation:
\[
\ce{
2Li_{ (s)} + 2H2O_{ (l)}\to 2LiOH_{ (aq)} + H2_{ (g)}
}
\]
(you may also write it with the lithium hydroxide as individual ions, that's fine, both are correct)
That'll get you one mark, and you should have been able to create this equation from looking at the electrochemical series. The next two will be about discussing problems with the cell. There are two safety concerns with the above equation:
1. Lithium hydroxide is a strong base, and so will be caustic (you should still be able to catch this in the ionic equation, as you'd have free hydroxide, which is the definition of a strong base - ionised hydroxide ions)
2. Hydrogen gas is generated, which is dangerous when uncontrolled
This would get you all three marks. However, if you also listed things such as:
3. Lithium hydrolysis is highly exothermic, and therefore dangerous
Or anything else I can't think of (ask me if unsure!), then they should each constitute one mark, as well.
VCAA can get a bit weird, so it might even be 3 marks distributed as - 1 for concern, 1 for equation, 1 for linking the two. But, my money would be on 1 for relevant equation, 1 for first concern, 1 for second concern.
EDIT: Now that I've said that, I reckon it is actually 1 for concern, 1 for equation, 1 for linking the two, because they haven't prompted you to give more than 1 reason, just to highlight why it might be unsafe with an equation. We'll know for sure when the assessor's report comes out, I guess
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Yeah, good question, I missed that. Since they mentioned you should use an equation, you 100% need to list the lithium hydrolysis equation:
\[
\ce{
Li_{ (s)} + H2O_{ (l)}\to LiOH_{ (aq)} + H2_{ (g)}
}
\]
(you may also write it with the lithium hydroxide as individual ions, that's fine, both are correct)
That'll get you one mark, and you should have been able to create this equation from looking at the electrochemical series. The next two will be about discussing problems with the cell. There are two safety concerns with the above equation:
1. Lithium hydroxide is a strong base, and so will be caustic (you should still be able to catch this in the ionic equation, as you'd have free hydroxide, which is the definition of a strong base - ionised hydroxide ions)
2. Hydrogen gas is generated, which is dangerous when uncontrolled
This would get you all three marks. However, if you also listed things such as:
3. Lithium hydrolysis is highly exothermic, and therefore dangerous
Or anything else I can't think of (ask me if unsure!), then they should each constitute one mark, as well.
VCAA can get a bit weird, so it might even be 3 marks distributed as - 1 for concern, 1 for equation, 1 for linking the two. But, my money would be on 1 for relevant equation, 1 for first concern, 1 for second concern.
EDIT: Now that I've said that, I reckon it is actually 1 for concern, 1 for equation, 1 for linking the two, because they haven't prompted you to give more than 1 reason, just to highlight why it might be unsafe with an equation. We'll know for sure when the assessor's report comes out, I guess
Would I lose a mark for making a mistake with balancing the equation in that q? Or they won’t care if I have that written down
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Would I lose a mark for making a mistake with balancing the equation in that q? Or they won’t care if I have that written down
You likely would lose the mark for writing the equation, because VCAA can be very finicky about that. However, if you used the equation as evidence, you would likely still get the evidence mark, because you have demonstrated that you understand what reaction is taking place. (having said that, I just looked up and noticed I forgot to balance it - oops. See now for properly balanced equation, if you based whether yours was balanced on mine)
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You likely would lose the mark for writing the equation, because VCAA can be very finicky about that. However, if you used the equation as evidence, you would likely still get the evidence mark, because you have demonstrated that you understand what reaction is taking place. (having said that, I just looked up and noticed I forgot to balance it - oops. See now for properly balanced equation, if you based whether yours was balanced on mine)
I honestly can’t remember, I may have possibly written Li(OH)2 lmao (and also with a solid state by accident too) so I’ll probs lose the mark for that