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

Can anyone explain the specification point - Explain how Condensation polymers may be photodegradable as the C=O bond absorbs radiation.

Is it just that the C=O bond absorbs IR and becomes weak and brittle, and the amide/ester bonds break?

Reply 541

alow

19

Original post by AqsaMx

Can anyone explain the specification point - Explain how Condensation polymers may be photodegradable as the C=O bond absorbs radiation.

Is it just that the C=O bond absorbs IR and becomes weak and brittle, and the amide/ester bonds break?

Please never use the word brittle to describe a chemical bond.

Reply 542

AqsaMx

5

Original post by alow

Please never use the word brittle to describe a chemical bond.

I meant the polymer becomes brittle

Reply 543

AqsaMx

5

Can anyone explain what a labile proton actually means? A proton that can be exchanged?

Reply 544

bakedbeans247

20

Original post by Saywhatyoumean

I wish I knew lol hang on let me find the question ImageUploadedByStudent Room1465078992.152548.jpg

ImageUploadedByStudent Room1465079079.845987.jpg

So when I'm drawing the spectrum, why is the CH2 singlet peak between 3.3-4.3ppm instead of ~2-3ppm?

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What year is this paper?! :O

Reply 545

bakedbeans247

20

I got 7.77...something

Reply 546

mechanism

5

Original post by suibster

surely it's because the carbon atom attached to the 2Hs is also attached to an oxygen.Therefore the corresponding chemical shift would be 3.3-4.3,which represents the HC-O proton signal.

Exactly, surely it would be HC-O bond, shift 3.3-4.3 and not the CH2 peak and a separate OH group? I'm so confused, I've always done it this way

Reply 547

Clankdroid

1

This is what me and my friend also got for the trichloroethanal question

Reply 548

ReeceM1

12

Has anyone got a list/diagram/poster of what transition metal reactions we need to know? Like all of the colours of the metal ions and the ligand exchange reactions?

Reply 549

rory58824

2

Original post by ReeceM1

Has anyone got a list/diagram/poster of what transition metal reactions we need to know? Like all of the colours of the metal ions and the ligand exchange reactions?

Have you looked at the specification? I think it explains very clearly what is required.

Reply 550

zirak46

8

Original post by ReeceM1

Has anyone got a list/diagram/poster of what transition metal reactions we need to know? Like all of the colours of the metal ions and the ligand exchange reactions?

Pretty sure its the last point on the specification, or atleast near the end

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Reply 551

seph_muriel

12

I really want to get an A in chemistry so I've done all the past papers on OCR website at least 3 times... would doing legacy papers be of any help or should I not even bother with them?! ADVICE PLEASE!!!

Reply 552

ImNervous

2

Original post by seph_muriel

I really want to get an A in chemistry so I've done all the past papers on OCR website at least 3 times... would doing legacy papers be of any help or should I not even bother with them?! ADVICE PLEASE!!!

I think as long as you've learnt all the content then doing legacy papers could help.
And where can you find them. I want to do them aswell. :yes:

Thanks

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Reply 553

rory58824

2

Plenty of old past papers here: http://pastpapers.org/chemistry-a2-papers

Enjoy everyone :wink:

Reply 554

AqsaMx

5

Could anyone explain this question? And why doesn't OH substitute the Iodine?

Reply 555

ImNervous

2

Original post by AqsaMx

Could anyone explain this question? And why doesn't OH substitute the Iodine?

I think it's just asking for structures with the molecular formula C4H8

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Reply 556

username986184

3

Original post by AqsaMx

Could anyone explain this question? And why doesn't OH substitute the Iodine?

OH is acting as a base under these conditions and so alkenes are formed. The conditions for nucleophilic substitution are different.

Reply 557

itsConnor_

11

Do we have to LEARN Sc3+ and Zn2+ are the only ions Sc/Zn form and therefore their respective electronic configurations prove that they are not transition elements? 6 marker came up on it a couple of years ago :s

Reply 558

zirak46

8

Original post by itsConnor_

Do we have to LEARN Sc3+ and Zn2+ are the only ions Sc/Zn form and therefore their respective electronic configurations prove that they are not transition elements? 6 marker came up on it a couple of years ago :s

Sc and Zn have only 1 stable ion, which is the one you said. Its not bad to remember, you just have to know their ion'a d subshell has 10e (for zn) and 0e (for Sc), so theyre not partially filled meaning theyre not transition elements

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Reply 559

Heisenberg___

3

Came across this fantastic link for old chemistry past papers. The person who made this has also kindly highlighted questions that we can skip (as they aren't relevant to our spec). Enjoy!

http://www.chemhume.co.uk/A2CHEM/ExamsMSA2/ExamMSA2%20additional.htm

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

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