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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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For the PLA question I wrote about how it can be hydrolysed in the body and then hydrogen bond with water molecules because of the polar cooh and oh group on lactic acid. I completely forgot about it being photodegradable too. Oh god..

Last I checked there's not a lot of light inside your body...

Reply 1761

Magicalgeofray

Can one of the Admins create a voting radio buttons things so we can all vote on what the A grade boundary will be please??

Reply 1762

izaa29

For the percentage yield question I got something like 7.26 g

Omds I feel like I'm the only one who failed this paper

It was easy but I made so many silly mistakes :frown:

I'm so upset now

Reply 1763

KB_97

Original post by Yazmin123

why?

I got nh3+ too. It's acid hydrolysis.

Reply 1764

dairychocolate

I didn't put photodegradable. I thought about it but photodegradation didn't seem to mesh with the dissolving.

I said that the ester linkages were hydrolysed and the lactic acid dissolved in water due to OH and COOH groups.

(edited 7 years ago)

Reply 1765

NervousBoy

Original post by KB_97

I got this for the last question. Compound J I think. Anybody else get this?

YES!

Reply 1766

lai812matthew

2 points at the chromatogram: I write 2 of 3 amino acids have same functional groups, similar adsorption ability, similar distance travel, they will overlap. stitches: I have only written that PLA can undergo hydrolysis to form lactic acid. PLA is solid in rtp because of its long branch and lactic acid is a liquid. NMR of amine: splitting is doublet, quartet of triplets, doublet. Gonna be all wrong I guess......

Reply 1767

FluffyCommie

Original post by Sahil_

Was there 3 chiral carbons for tripeptide, 2 on the middle carbon of the amino acids apart from glycine and 1 on the R group for the aminoacid with the long r group?

yes, there were 3 chiral carbons for the tripeptide :smile:

Reply 1768

Magicalgeofray

Original post by KB_97

I got this for the last question. Compound J I think. Anybody else get this?

Yeah thats what i got too, have 9 in the proton environment of a singlet so had to be this.

Reply 1769

username2097061

Original post by Yazmin123

why?

As they specifically specified HCL, you had to write NH3 Cl or NH3+ Cl-...

I knew a lot of people would miss that out.

Reply 1770

hw22

Original post by izaa29

For the percentage yield question I got something like 7.26 g

Omds I feel like I'm the only one who failed this paper

It was easy but I made so many silly mistakes :frown:

I'm so upset now

I got that aswell :frown:

Reply 1771

Arima

Wait you guys... was there a benzene question comparing reactivities? There's one every year but i don't remember there being one this year? UM

Reply 1772

KB_97

Original post by GillyTheGhillie

Last I checked there's not a lot of light inside your body...

Not but it was for stitches. And your skin is exposed to uv from sunlight so...idk. I didn't put it down so I hope the answer isn't that it's photodegradable.