Help on a OCR Chemistry Past Paper Question- Identifying Compounds

Hi all, please could you help me on the last question of June 2013 F324.

The part that I am stuck with is when you have identified the structure of the unknown compound but the mark scheme says that you get 2 marks for the correct structure drawn but flipped. And one mark for the way I have drawn it. It is the correct structure but you get more marks for drawing it one way than the other. So, how do I know which way they want me to draw it?

Please see the mark scheme to understand what I am talking about. Thanks!

(edited 9 years ago)

Reply 1

Ch@r10tte

6

Are you sure it was June 2013 F325? I just did that question, and it doesn't mention anything about structure drawing (finds formula of Ni(II) salt). DO you mean the F324, identifying 'compound L'?

Reply 2

RevisionNad

OP

17

Original post by Ch@r10tte

Are you sure it was June 2013 F325? I just did that question, and it doesn't mention anything about structure drawing (finds formula of Ni(II) salt). DO you mean the F324, identifying 'compound L'?

Hiya, yes a typo, it's F324. Please could you help,

Thanks

Reply 3

Ch@r10tte

6

Original post by RevisionNad

Hiya, yes a typo, it's F324. Please could you help,

Thanks

The correct two mark structure given in the mark scheme has the benzene directly attached to the oxygen, then bonded to a carbon with a double bond O, etc., whereas the incorrect structure has the benzene bonded directly to the carbon, rather than via the oxygen. This is not entirely correct, as the multiplet at 2.7ppm (from the proton NMR) shows a single hydrogen on a carbon, which is attached to the C=O, rather than directly to oxygen. I've attached a drawing, which should hopefully explain it better, but please excuse the bad mouse drawing. I hope this clears things up.

OP

Original post by Ch@r10tte

The correct two mark structure given in the mark scheme has the benzene directly attached to the oxygen, then bonded to a carbon with a double bond O, etc., whereas the incorrect structure has the benzene bonded directly to the carbon, rather than via the oxygen. This is not entirely correct, as the multiplet at 2.7ppm (from the proton NMR) shows a single hydrogen on a carbon, which is attached to the C=O, rather than directly to oxygen. I've attached a drawing, which should hopefully explain it better, but please excuse the bad mouse drawing. I hope this clears things up.

Thanks- you're a star! Just one more question- I drew the whole structure flipped i.e. the mirror image of the correct answer- would this still get 2 marks?

Reply 5

Ch@r10tte

6

Original post by RevisionNad

Thanks- you're a star! Just one more question- I drew the whole structure flipped i.e. the mirror image of the correct answer- would this still get 2 marks?