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

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Sorry where is the presentation? :smile:

It's from https://www.cpdhub.ocr.org.uk/ which requires a (free) registration, however I've also uploaded a copy here: https://my.mixtape.moe/gfofsl.pdf

Reply 901

ranz

Original post by suibster

Assume the chemical shift is at where it indicates.

so if theres a peak at 2 then i should assume they mean at 1 ppm?

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Reply 902

itsConnor_

Original post by marioman

It's from https://www.cpdhub.ocr.org.uk/ which requires a (free) registration, however I've also uploaded a copy here: https://my.mixtape.moe/gfofsl.pdf

WOW thanks so much

Reply 903

AqsaMx

Original post by ImNervous

I think the height of the peak at 122 m/e would be greater as it does not contain the isotope so is more abundant? Not really sure though

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I believe the answer is 1:1 so not sure..

Reply 904

ranz

Original post by AqsaMx

I believe the answer is 1:1 so not sure..

i dont think we need to know this though? or am i wrong

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Reply 905

AqsaMx

Original post by ranz

i dont think we need to know this though? or am i wrong

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It's to do with fragments ( mass spec) and its synoptic from as I believe

Reply 906

ranz

guys if theres an aldehyde for example, would there be a peak at both 9.5 ppm ( -CHO) and 3.5 ppm (HC-O) for thr aldehyde

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Reply 907

RayMasterio

Original post by itsConnor_

But surely if stationary phase is solid, it separates by adsorption and if the stationary phase is a liquid, it separates by relative solubilities?

Original post by AqsaMx

I don't have the paper, it was given to me as a pack but the answer was adsorption..

If the stationary phase is liquid, then the separation occurs by relative solubility.
If the stationary phase is a solid, then the separation occurs by adsorption

Reply 908

ranz

Original post by RayMasterio

If the stationary phase is liquid, then the separation occurs by relative solubility.
If the stationary phase is a solid, then the separation occurs by adsorption

isnt gc always relative solubility and tlc adsorption?

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Reply 909

RayMasterio

Original post by ranz

isnt gc always relative solubility and tlc adsorption?

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If the stationary phase in GC is a liquid, then the separation is done by relative solubility. If it was a solid, then it will be adsorption

Reply 910

Serine Soul

With NMR I go like this...

Let's just say

Triplet peak at 0.8ppm with peak area of 2 shows 2xH in CH2, adjacent to CH2

And do the same for every peak in the spectra...

Isn't that just as fine?

Reply 911

marioman

Original post by Serine Soul

With NMR I go like this...

Let's just say

Triplet peak at 0.8ppm with peak area of 2 shows 2xH in CH2, adjacent to CH2

And do the same for every peak in the spectra...

Isn't that just as fine?

That's fine. There's no specific format that you must follow, as long as you put the info in you will get the marks!

Reply 912

Serine Soul

Original post by ranz

guys if theres an aldehyde for example, would there be a peak at both 9.5 ppm ( -CHO) and 3.5 ppm (HC-O) for thr aldehyde

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No...
Aldehydes consist of C=O bonds, not C-O bonds, so only a peak between 9 - 10 ppm, and 2-3 ppm if there's another CH attached to the C in C=O

(edited 7 years ago)

Reply 913

Serine Soul

Original post by marioman

That's fine. There's no specific format that you must follow, as long as you put the info in you will get the marks!

Yeah, the table looks really tidy though! (I'm a messy person) just wish I had been told to use it earlier :frown:

Reply 914

ranz

Original post by Serine Soul

No...
Aldehydes consist of C=O bonds, not C-O bonds, so only a peak between 9 - 10 ppm, and 2-3 ppm if there's another CH attached to the C in C=O

so if theres a carbon attached to the aldehyde it would show up as HC-O 2-3 ppm?

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Reply 915

RayMasterio

can someone please tell me how to approach these questions? the method for them changes everytime and I never get full marks even though these are supposed to be easy marks

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Reply 916

ranz

Original post by RayMasterio

can someone please tell me how to approach these questions? the method for them changes everytime and I never get full marks even though these are supposed to be easy marks