Aqa chem4 15th june 2011 (resit) thread

was that all that you had to mention?

Damn! I just realised I put Na2CO3, not NaH!

Benzen ene benzene is -120kj mol-1
so we'd assumed that a benzene triene would be -360KJ mol-1 (3x-120)
However benzene have a enthaply change of about -220 KJ mol-1 (forget the exact enthaply change)

Therefore benzene is more stable than benzene triene.

Did you mention any of this?

It was 6 marks and I'm not sure what else to add..so I also think I've lost marks too :|

edit - I added equations too

Wasn't this question 4 marks? I didn't know this either!! NOPE, mentioned NONE of that, I talked about the benzene ring and the delocalised electrons! Pure guess as I stupidly didn't go over this

I was talking about the cyclohexene reagents one towards the end! Reagents and mechanism for 6 marks - steps 3 and 4. Argh, got it completely wrong :/

Ohhhhhhh lool sorry. My recollection of yesterday's exam is diminishing.

I think you'll actually get 2 marks for that. Someone told me you were supposed to mention that.

Ohh, I did stretch my head for that one.

Did you put purple AND yellow or purple TO yellow? Cos' it said colour change?

Benzen ene benzene is -120kj mol-1
so we'd assumed that a benzene triene would be -360KJ mol-1 (3x-120)
However benzene have a enthaply change of about -220 KJ mol-1 (forget the exact enthaply change)

Therefore benzene is more stable than benzene triene.

Did you mention any of this?

It was 6 marks and I'm not sure what else to add..so I also think I've lost marks too :|

edit - I added equations too

I just put 'yellow'...

Would i lose the mark? It didn't mention that the indicator was purple to start with (although it was alkali - but they didn't say they had tested it b4 adding acid?) so i just put yellow, hope i dont get it wrong, that would be a bit harsh...

dynamic equilibrium is it rate of forward reaction=rate of backward reaction, all the states are similar. will this gain me 2mks

i wrote that too! then i subtracted it and wrote something about there being a -152KJ difference?

no, you had to put the reaction of forwards and backwards reactions are equal
AND so there are no changes in the concentrations of reactants or products.

it said explain it too, so you had to mention the delocalised electrons making it exist in a more stable state.

Haha no worries, I'm quite bad at remembering questions have exams too

Ah not so bad :/ But the 6 mark one, ah I was gutted as I knew the answer for the mechanisms but I mistaken it for an aromatic compound and went down the H2/Ni route

You went down the right route! if it was aromatic you would use Sn/Hcl to reduce it

I think they mean it was the wrong reaction, it was an hexene not a Benzene as a lot of people thought.

Ohh rightt. So would you do electrophillic addition with Hbr. Then nucleophillic substitution with excess Nh3?

Apparently so and the reaction was actually easy if they had made it clear. I still think AQA are abit weird and now loads of students are going to lose mark for that Question.

including me

no, you had to put the reaction of forwards and backwards reactions are equal
AND so there are no changes in the concentrations of reactants or products.

you mean i wont even earn a mark

Thats what I wrote probably the only marks I got in that exam. :/ But I do agree that the question was really weird. They intentionally set out to trick people with that one. The least they could've done was name the compound so people wouldn't confuse it with benzene.