Suggested Answers and Discussion for the 2016 VCE Chemistry Exam

[humanwhostudies]

For a reaction to occur the iodine and copper must be able to be in contact. The grease should prevent contact between copper and iodine, stopping a reaction from occurring.

but doesn't that mean the answer can't be D, as the question asks what could NOT explain the result

[shlblk]

For a reaction to occur the iodine and copper must be able to be in contact. The grease should prevent contact between copper and iodine, stopping a reaction from occurring.

This sounds right. I didn't even think about it like that.

[thushan]

Solutions up as PDF on first post, will need an account to download them for now sorry! Brenden will embed them onto main post ASAP.

[Cal.McCrimmon]

Pretty sure the answer was C. The copper would react with bromine just as it would react with iodine, thus the addition of bromine isn't a plausible reason to observe no reaction. The other options were all possible reasons to observe no reaction

[sweetcheeks]

Solutions up as PDF on first post, will need an account to download them for now sorry! Brenden will embed them onto main post ASAP.

Thanks

Just a question with multiple choice 24, I got B which I thought was correct but you have A listed. I ended up with ~47kJ of octane and 22.6 kJ of methanol. Have I made a mistake

[shlblk]

Thanks

Just a question with multiple choice 24, I got B which I thought was correct but you have A listed. I ended up with ~47kJ of octane and 22.6 kJ of methanol. Have I made a mistake

I got B as well.

[julijulib]

I got B as well.

ditto

[HopefulLawStudent]

Does anyone have a copy of the exam??

EDIT: Lol nvm.

[thushan]

I got B as well.

Fiddlesticks, you're right. I didn't see the coefficient of 2. Fixed it in the main doc.

[asdasdasd123]

hey thushan, wouldnt 8a be negative as when the graphite electrode is discharging, its the anode?

[julijulib]

would someone please be able to explain why the addition reaction with chlorine is redox? 

[thushan]

hey thushan, wouldnt 8a be negative as when the graphite electrode is discharging, its the anode?

Bum - fixed it. Wrote it correctly on my exam paper copy, transcribed it wrong onto the word doc. You're right, it's negative.

[Samm1]

For an advantage of a secondary cell compared to a fuel cell. Would a secondary cell not needing a constant flow of reactants and therefore cheaper be an advantage?

[thushan]

would someone please be able to explain why the addition reaction with chlorine is redox? 

Oxidation number of Cl drops from 0 to -1.

[thushan]

For an advantage of a secondary cell compared to a fuel cell. Would a secondary cell not needing a constant flow of reactants and therefore cheaper be an advantage?

Hmm - can't say it's cheaper specifically, because you need electricity to recharge the secondary cell, which costs money as well :/