OCR A Chemistry F324 Rings, Polymers and Analysis Thu 26 Jan 2012

stop stressing over the last question, you get marks for working out
empirical formula
molecular formula
identifying peaks, splittings, fragments,

then the structure which is worth like 2 marks..so chillout

If f324 was a "not too horrible" paper, that means f325 should be horrible?

I BET PEOPLE GOT THIS Q WRONG:

when reacting acid anhydride with alcohol i drew the ester wrong by not flipping the alcohol!!!! damnnnnnnnnnnnnn was is 2 marks?

Reply 921

rogersnm

4

Original post by 079

stop stressing over the last question, you get marks for working out
empirical formula
molecular formula
identifying peaks, splittings, fragments,

then the structure which is worth like 2 marks..so chillout

If f324 was a "not too horrible" paper, that means f325 should be horrible?

I BET PEOPLE GOT THIS Q WRONG:

when reacting acid anhydride with alcohol i drew the ester wrong by not flipping the alcohol!!!! damnnnnnnnnnnnnn was is 2 marks?

How do you mean "flipping" the alcohol?

Reply 922

079

screw diamers!!! that question hurt my brain lool I couldnt draw it!!!

Reply 923

H_Rattan

what did everyone write for the identifying the ketone question? determining whether it was pentan-2-one or pentan-3-one?

Reply 924

079

Original post by rogersnm

How do you mean "flipping" the alcohol?

as in say the structural formula of the alcoholis CH3CH2OH
when its joined to the ester you have to write it lime
(carboxylic part)-OCH2CH3

Reply 925

Messara2

Original post by 079

screw diamers!!! that question hurt my brain lool I couldnt draw it!!!

for diamers i just drew the hexagon that they gave except i changed the r group.
was quite clever how you had to add an arrow from o- to h+ but overall was a niceee paper

Reply 926

rogersnm

4

Original post by H_Rattan

what did everyone write for the identifying the ketone question? determining whether it was pentan-2-one or pentan-3-one?

For Part 1) React it with 2,4-dinitrophenylhydrazine, it will form an orange precipitate. Warm it with Tollens' reagent, no reaction will occur.
Part 2) Filter and purify the orange precipitate then do a melting point test. Compare the melting point to data tables to identify the original compound.

Reply 927

079

Original post by H_Rattan

what did everyone write for the identifying the ketone question? determining whether it was pentan-2-one or pentan-3-one?

i said 2,4dnp to prove its carbonyl
then tollens reagent, if no silver mirror then ketone

then (after the 2,4dnp test)
Purify by recrystallisation
measure melting point
compare with database

Reply 928

l.a.s

Firstly: for the alkaline hydrolysis of the polyamide, does the -OH on the phenol become -O-Na+ as well? or just on the carboxylic acid?
Secondly: which has the longest retention time with an alkane stationary phase? the alkane or alcohol?

Reply 929

fudgesundae

16

Original post by l.a.s

Firstly: for the alkaline hydrolysis of the polyamide, does the -OH on the phenol become -O-Na+ as well? or just on the carboxylic acid?
Secondly: which has the longest retention time with an alkane stationary phase? the alkane or alcohol?

I think it was meant to be O-Na+. I left it as OH though :frown:

Reply 930

Zoe_mj

Original post by fudgesundae

But if step 3 showed an Oxygen with a negative charge, then surely it picks up a proton during step 3 or after this?

The question asked for curly arrows in step 1 and 2.

Plus it was 4 marks. 1 for each of 3 curly arrows, 1 for the intermediate.

But by doing the first part and intermediate was only step 1, because the step 1 arrow was in between them, step 2 was what happened to the intermediate, cause that arrow was between intermediate and last part.

Reply 931

rogersnm

4

Original post by l.a.s

Firstly: for the alkaline hydrolysis of the polyamide, does the -OH on the phenol become -O-Na+ as well? or just on the carboxylic acid?
Secondly: which has the longest retention time with an alkane stationary phase? the alkane or alcohol?

1. Yes, phenol reacts with sodium hydroxide to form sodium phenoxide (+water)
2. Haven't the foggiest

Reply 932

H_Rattan

Original post by 079

i said 2,4dnp to prove its carbonyl
then tollens reagent, if no silver mirror then ketone

then (after the 2,4dnp test)
Purify by recrystallisation
measure melting point
compare with database

yes i said that :smile:

Reply 933

queeniemuah

i think the grade boundaries are going to be quite high cos they added 15 mins to the paper.... :frown:

Reply 934

079

I got a B in this last year, I dont think ive improved...looks like heart and soul need to be put into unit 5 next week

Reply 935

fudgesundae

16

Original post by Zoe_mj

But by doing the first part and intermediate was only step 1, because the step 1 arrow was in between them, step 2 was what happened to the intermediate, cause that arrow was between intermediate and last part.

Was the intermediate not step 2?

I thought I saw a step 3 lol, oh well.

Reply 936

Phenylethylamine_

Think I got 50/60... :frown:

Reply 937

Zoe_mj

Original post by queeniemuah

i think the grade boundaries are going to be quite high cos they added 15 mins to the paper.... :frown:

That was for the stretch and challenge questions.
They've added questions which make you think more to distiguish A* pupils from A pupils, so gave us a bit extra time too. This shouldnt have an effect on the grade boundaries really :smile:

Reply 938

holahola

What was the answer for br2 ?