Aqa chem 4/ chem 5 june 2016 thread

I put the same. I think because its in excess any change will be very small compared with how much there is. Is it like taking [H2O] out of Kw ?

What did people put for the mechanism on the second question??

What everyone get for theire answers

For the ph one i got - 3.33
For the salt ethanoic one i got - 1.20
For the Kc one i got - 9.09x10^3?

That wasn't too bad, just a bit unlike past papers and I was REALLY pushed for time. I finished as she said 'pens down'.

Did anyone else get the rate expression as exactly the same in the question?
Yes
Also, what was the reason for lidocaine hydrochloride? I said to prevent the N acting as a base by protonating it and so reduces side effects. I spent about 5 minutes looking for a chiral carbon in that compound to talk about enantiomers, but I couldn't see one!

That wasn't too bad, just a bit unlike past papers and I was REALLY pushed for time. I finished as she said 'pens down'.

Did anyone else get the rate expression as exactly the same in the question?

Also, what was the reason for lidocaine hydrochloride? I said to prevent the N acting as a base by protonating it and so reduces side effects. I spent about 5 minutes looking for a chiral carbon in that compound to talk about enantiomers, but I couldn't see one!

What were the reagents and conditions in the organic synthesis question?

Step 3 was a substitution question to go from Br to a CN group. So I said KCN aqueous and alcohol.

The final step was reduction, so Hydrogen & Nickel Catalyst.

Do you have nothing better to do?

Step 3 was a substitution question to go from Br to a CN group. So I said KCN aqueous and alcohol.

The final step was reduction, so Hydrogen & Nickel Catalyst.

What did people put for the mechanism on the second question??

Are you joking?😱

was going to put both but it said only 1 condition so ijust put alcoholic. im sure both will be right too though

Very nearly it was ch3-o-ch2-ch2-c (ch3)2 (oh)

I put that but its wrong, that gives you a tertiary alcohol and it doesn't form a green ppt

I think this is what I put:

KCN ethanolic aqueous solution

then

LiAlH4 ether

I agree. The only thing affecting Kc is temperature - thus rate will only depend on the differing ratio of propanone to protons.

Don't worry, others said they found it hard, I suspect 120 UMS will be no higher than 90.

Step 3 was a substitution question to go from Br to a CN group. So I said KCN aqueous and alcohol.

The final step was reduction, so Hydrogen & Nickel Catalyst.

I think this is what I put:

KCN ethanolic aqueous solution

then

LiAlH4 ether

ethanolic KCN and AlLiH4 in ether (or hydrogen with nickel catalyst)

Please someone say that exam was hard for them too... I started having a panic attack in there... It went horribly and I revised so much for this exam