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

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Original post by AqsaMx
What name is given to the process by which components are separated by gas/liquid chromatography?

I thought the answer was relative solubility, but the MS says Adsorption???


Depends on stationary phase, what it the question? :smile:
Original post by RayMasterio
If the Benzene ring did not have the circle in the middle, it would be c6h12 right?


yeah it would be cyclohexane, C6H12
Reply 842
guys just did 2015 paper what the hell! they cant pack soo many questions in one paper. so manny questions required soooo much time just for 1-2 marks, ridicilious! at least make the nmr qs easy.


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Do we have to know that phenol reacts with hydroxide ion(s) to form water and a phenoxide ion?
I understand that phenol will react with metallic alkali's like NaOH, but was just curious as to whether need to know.
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For the last NMR question in RPA June 2013 can anyone explain why there are only 3 peaks in the hydrogen NMR spectrum? I get the 2 environments attached to the side chain, but I make 3 environments out of the benzene ring not 1? Thanks
Reply 846
guys isnt h2so4 used as a catalyst why is it reacting with nh2 ?


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Original post by ranz
guys isnt h2so4 used as a catalyst why is it reacting with nh2 ?


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NH2 is basic, although sulphuric acid is being used as a catalyst, it still reacts with the amino group

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Original post by ForeverDay
For the last NMR question in RPA June 2013 can anyone explain why there are only 3 peaks in the hydrogen NMR spectrum? I get the 2 environments attached to the side chain, but I make 3 environments out of the benzene ring not 1? Thanks


RPA?

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Original post by ranz
guys isnt h2so4 used as a catalyst why is it reacting with nh2 ?


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I suppose the reaction is still done in acidic conditions so NH3 reacts? I think if you ever see an acid involved in a reaction with a compound that has an NH or NH2 on, its going to react too NH2+ or NH3+
Original post by itsConnor_
Sorry but in 4-aminophenol ( https://gyazo.com/28ae388c73b6a5f851cee6dd42f8d250 ) when it accepts a proton does it form a covalent or ionic bond? i was thinking about it forming a dative covalent bond with the hydrogen due to its lone pair, is this right? cos then again it goes to NH3+ doesnt it?

Also how does it act as a base (in the question) if the lone pair of electrons are delocalised into the ring?

Thanks. :smile:


Can someone pls clarify for me? :smile:
Original post by itsConnor_
Can someone pls clarify for me? :smile:


Dative Covalent for your first question,

and for your second question presumably the oxygen atom is more electronegative than the nitrogen atom, so the lone pair of electrons on oxygen atoms are delocalised into the ring which means the nitrogen has a long pair of electrons that are able to accept the proton.
Reply 852
Original post by pineneedles
NH2 is basic, although sulphuric acid is being used as a catalyst, it still reacts with the amino group

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i see, after its done its job it reacts with nh


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Reply 853
Original post by itsConnor_
Depends on stationary phase, what it the question? :smile:


That is the question ^
Original post by AqsaMx
That is the question ^


Which paper is this?
Reply 855
image.jpeg

Can anyone explain the relative heights question? What's it even asking?
Reply 856
Original post by itsConnor_
Which paper is this?


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

But surely if stationary phase is solid, it separates by adsorption and if the stationary phase is a liquid, it separates by relative solubilities?
Reply 858
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?


Yeah but it doesn't tell you the stationary phase, it asks about gas/liquid chromatography and gas separates by relative solubilities right?
Reply 859
How would you form a carboxylic acid from its salt?

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