2010 VCAA Chemistry U4 Suggested solutions

[cama23]

lost a maximum of 5 marks, A+ here i come!
shit yeahhhhh

[Mao]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

I challenge this. Source? (journal article, textbook reference, anything?)

[10weid]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not.

whatever the answer is, (and this isnt me admitting defeat:P), ill take my 46-4 in chem, it'll be in my bottom 2, and prepare for my interview:)
as long as they dont ask me about the rechargeable nature of fuel cells in relation to medicine! :p

[mirra250]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not. On top of that I've never read that they are. And seriously? How can you get the reactions to go backward in there? Split the H2O up?..

LMAO.. yes.. it's called electrolysis of water

[Souljette_93]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Regardless if they are or not, it's all going to depend on what VCAA accepts. They are the one's who is going to give the mark.

[Mao]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not.

whatever the answer is, (and this isnt me admitting defeat:P), ill take my 46-4 in chem, it'll be in my bottom 2, and prepare for my interview:)
as long as they dont ask me about the rechargeable nature of fuel cells in relation to medicine! :p

GL man I still want you to prove to me I am wrong. I firmly believe there's no such thing as 'rechargeable fuel cell', that'll be like a 'two-directional hose' for watering your garden..


Well, looks like the discussion have calmed down a bit. I will go get out of bed now and do some boring stuff. I'll be back later tonight, don't hesitate to email.

[Mao]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not. On top of that I've never read that they are. And seriously? How can you get the reactions to go backward in there? Split the H2O up?..

LMAO.. yes.. it's called electrolysis of water

ELECTROLYSIS OF WATER DOESN'T USE A BLOODY POROUS PLATINUM ELECTRODE!!!@!@!@ (sorry )

[m@tty]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not. On top of that I've never read that they are. And seriously? How can you get the reactions to go backward in there? Split the H2O up?..

LMAO.. yes.. it's called electrolysis of water

How would you do this in the fuel cell? The H2O is released into the atmosphere.. Clearly you can't electrolyse it..


EDIT: what Mao said..

[mustafa]

I'm
sure fuel cells are rechargeable.

Last year the assessors said try ACCEPTED responses saying fuel cells were unrechargeable. Which means they can be recharged, but VCAA was just being nice.

[m@tty]

I don't know if it has been contested yet.. But I believe you've got 18 wrong. It was being electrolysed. So the strongest oxidant is oxidised.. I believe that the correct answer is A. The anode reaction is the oxidation of the sulfate ion and the cathode is the reduction of water..

I think you missed that a current was being supplied?

[mirra250]

ok, just asked my dad, who has a medical degree with an additional year of study in chemistry, and topped chemistry at melb university 2 years in a row, he said fuel cells ARE rechargeable,.

Last years examiner's report clearly said they were not. On top of that I've never read that they are. And seriously? How can you get the reactions to go backward in there? Split the H2O up?..

LMAO.. yes.. it's called electrolysis of water

How would you do this in the fuel cell? The H2O is released into the atmosphere.. Clearly you can't electrolyse it..


EDIT: what Mao said..

LOL how are they not electrolysed with a porous platinum electrode?
and clearly the water can be harnessed and pumped back into the fuel cell just as the O2 and H2 are and then applied electricity to it. Clearly it would never happen but does not make it impossible

[Mao]

I'm
sure fuel cells are rechargeable.

Last year the assessors said try ACCEPTED responses saying fuel cells were unrechargeable. Which means they can be recharged, but VCAA was just being nice.

Your tap in the sink can also suck up water, but at no point in their operation will they return water to the dam against the main flow. Same principle.

[98.40_for_sure]

I don't know if it has been contested yet.. But I believe you've got 18 wrong. It was being electrolysed. So the strongest oxidant is oxidised.. I believe that the correct answer is B. The anode reaction is the oxidation of the sulfate ion and the cathode is the reduction of water..

I think you missed that a current was being supplied?

Download the updated one

[Mao]

I don't know if it has been contested yet.. But I believe you've got 18 wrong. It was being electrolysed. So the strongest oxidant is oxidised.. I believe that the correct answer is B. The anode reaction is the oxidation of the sulfate ion and the cathode is the reduction of water..

I think you missed that a current was being supplied?

My 18 is B?

[mirra250]

I don't know if it has been contested yet.. But I believe you've got 18 wrong. It was being electrolysed. So the strongest oxidant is oxidised.. I believe that the correct answer is B. The anode reaction is the oxidation of the sulfate ion and the cathode is the reduction of water..

I think you missed that a current was being supplied?

that was incoherent but nonetheless incorrect. an oxidant is REDUCED, a reductant is OXIDISED. In this reaction, water is the strongest reductant hence is oxidised