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

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Reply 1340

Sarcastic Goats

Do we need to learn the monomers that make Nylon and Kevlar?

Reply 1341

tcameron

Original post by sakuraton

Well, I thought carboxylic acid can't be reduced and the mark scheme shows that carboxylic acid being reduced? I'm just confused, that is all.
I know Aldehyde and Ketone can be reduced.
I'm just gonna leave it and hope a nice paper tomorrow.

the carboxylic acid was not being reduced - it was being dehydrated which is just removal of water - the carboxyl group wasn't even affected in that reaction.

Reply 1342

itsConnor_

Original post by M0n1

does anyone have a copy of 2015 papers for F324??

https://www.dropbox.com/sh/kwj0elokp2hco0c/AADgT1LXHwXXFXE6S-r2mI-Pa?dl=0

Reply 1343

itsConnor_

Original post by Sarcastic Goats

Do we need to learn the monomers that make Nylon and Kevlar?

Nope

Reply 1344

shamsaidk

lol @ all of you 99% ready........idek what tms does

Reply 1345

Magicalgeofray

Original post by Sarcastic Goats

Do we need to learn the monomers that make Nylon and Kevlar?

No but its known as Nylon 6,6 so 6 carbons on both the dicarboxylic acid and diamide

Reply 1346

itsConnor_

Original post by lai812matthew

huh? i copy it from wikipedia. that's what concerns me. definition that i know about zwitterion: An ionic form of an amino acid that contains both positively and negatively charged groups. As both charges are present there is no overall charge.

Look at all the OCR A questions involving zwitterions, with varying R groups. The R group is never affected in zwitterions (if we want to get the marks). :smile:

Reply 1347

Magicalgeofray

Original post by shamsaidk

lol @ all of you 99% ready........idek what tms does

Is the standard reference peak, is very large as all the protons are in the same environment

Reply 1348

itsConnor_

Original post by shamsaidk

lol @ all of you 99% ready........idek what tms does

Standard for chemical shift measurements (quoted from spec)

Reply 1349

sakuraton

Original post by tcameron

the carboxylic acid was not being reduced - it was being dehydrated which is just removal of water - the carboxyl group wasn't even affected in that reaction.

AFTER the elimination of H2O, you see the word 'reduction' O.O

Reply 1350

tcameron

Original post by shamsaidk

lol @ all of you 99% ready........idek what tms does

TMS is the standard for all chemical shift measurements
It has a chemical shift of 0
it's structure is Silicon surrounded by 4xCH3 groups

hope that helps

Reply 1351

ranz

Original post by CalistaJupiter

They don't all protonate… I did a past paper that had a 'zwitterion' with an extra cooh side group and the mark scheme said "reject if both cooh groups are shown to have donated a proton" because only groups directly involved in being an amino acid (eg RCH(NH2)COOH) actually protonate

yh cus there are unequal number of cooh to nh2, my confusion is what if there was equal amount of both. the charge would still be neutral

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Reply 1352

Serine Soul

Who's fasting during the exam tomorrow?

It's my first exam fasting so I'm slightly nervous!

Reply 1353

itsConnor_

Original post by tcameron

TMS is the standard for all chemical shift measurements
It has a chemical shift of 0
it's structure is Silicon surrounded by 4xCH3 groups

hope that helps

we dont need to know of structure right?

Reply 1354

Magicalgeofray

Original post by itsConnor_

Standard for chemical shift measurements (quoted from spec)

I guess you're doing the same as me, trying to look at as much stuff on here, its all revision at the end of the day :smile:

Good luck tomorrow, i think NMR will be my downfall, i struggle to imagine Benzene ring protons as their splilting patterns as they are multiplets because in essence they are all adjacent to one another, because all delocalised in the Pi system