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OCR F324-June 2013 Chemistry

Reply 2080

OP

The diazonium depends on its side chain function groups so 3-nitrodiazonium chloride or 4-methylphenyldiazonium chloride etc.

I see and what about azo dyes?

Reply 2081

_HabibaH_

8

Original post by otrivine

I see and what about azo dyes?

I don't think we need to know. Nowhere in the book or PP questions has it told us how to name or asked us for a name.

Reply 2082

kuku2013

can someone summarise what I need to know on triglycerides, diet, and health please

Reply 2083

otrivine

OP

14

Original post by MathsNerd1

Okay, what changes the isoelectric point on an amino acid, I'm not sure if something like this could come up though.

amino acids are amphoteric so could either act as a base or an acid? So, could act as a base and accept proton which becomes COO- as the H+ is lost from carboxyl group and could act as acid and donate a proton to the NH2 to become H3N+

Reply 2084

otrivine

OP

14

Original post by _HabibaH_

I don't think we need to know. Nowhere in the book or PP questions has it told us how to name or asked us for a name.

Do we have to memorise on producing the chromatogram, its not in the syllabus?

Reply 2085

MathsNerd1

17

Original post by otrivine

amino acids are amphoteric so could either act as a base or an acid? So, could act as a base and accept proton which becomes COO- as the H+ is lost from carboxyl group and could act as acid and donate a proton to the NH2 to become H3N+

Don't quote me on this but I always thought it was the number of amine groups which changed the isoelectric point, although I suppose it could work the same way with carboxylic acid groups.

Reply 2086

duharvalgt

7

Original post by Raafae

In June 2010 paper for 1bi it says that the nitronium ion has to be substituted at a specific position on the benzene ring otherwise you get penalised. Does anyone know the rules for substitution onto the benzene ring

Paper: http://www.ocr.org.uk/Images/59707-question-paper-unit-f324-rings-polymers-and-analysis.pdf
Mark scheme: http://www.ocr.org.uk/Images/59704-mark-scheme-unit-f324-rings-polymers-and-analysis-june.pdf

Thank you :smile:

Look at the position of the N=N bond in sudan II

Reply 2087

otrivine

OP

14

Original post by MathsNerd1

Don't quote me on this but I always thought it was the number of amine groups which changed the isoelectric point, although I suppose it could work the same way with carboxylic acid groups.

Good question, in the exam if they asked this ill put both in to be on the safe side, they dont contridict right

Reply 2088

Brad0440

Original post by Raafae

In June 2010 paper for 1bi it says that the nitronium ion has to be substituted at a specific position on the benzene ring otherwise you get penalised. Does anyone know the rules for substitution onto the benzene ring

Paper: http://www.ocr.org.uk/Images/59707-question-paper-unit-f324-rings-polymers-and-analysis.pdf
Mark scheme: http://www.ocr.org.uk/Images/59704-mark-scheme-unit-f324-rings-polymers-and-analysis-june.pdf

Thank you :smile:

Generally I don't think it matters, but in this question because we are given the end product all of the steps must agree with the structure of the end product. So because in the end product the -N=N- part on the benzene ring in opposite one methyl group and adjacent to another, then the NO₂, NH₂ and N=N groups must all also be in this position.

Reply 2089

_HabibaH_

8

Original post by otrivine

Do we have to memorise on producing the chromatogram, its not in the syllabus?

If it's not on our syllabus then I don't see why we'd have to. But for understanding purposes, it wouldn't harm to learn it.

Reply 2090

MathsNerd1

17

Original post by otrivine

Good question, in the exam if they asked this ill put both in to be on the safe side, they dont contridict right

I don't think so because one will increase it and the other would decrease it so they're both changing the isoelectric point really

Reply 2091

otrivine

OP

14

Original post by _HabibaH_

If it's not on our syllabus then I don't see why we'd have to. But for understanding purposes, it wouldn't harm to learn it.

did you memorise the information on producing the chromarogram ?

Reply 2092

otrivine

OP

14

Original post by MathsNerd1

I don't think so because one will increase it and the other would decrease it so they're both changing the isoelectric point really

true

Did you memorise how to produce a chromatogram?

Reply 2093

amin666

Original post by otrivine

Good question, in the exam if they asked this ill put both in to be on the safe side, they dont contridict right

no the isoelectric point depends on the R connected with the alpha carbon

Reply 2094

_HabibaH_

8

Original post by MathsNerd1

Don't quote me on this but I always thought it was the number of amine groups which changed the isoelectric point, although I suppose it could work the same way with carboxylic acid groups.

I though the R group was only affected if it was in a solution of excess acid/base, but at the isoelectric point only one amine/carboxyl group would exchange H+

Reply 2095

MathsNerd1

17

Original post by _HabibaH_

I though the R group was only affected if it was in a solution of excess acid/base, but at the isoelectric point only one amine/carboxyl group would exchange H+

Hmm, I'm not too sure sorry, it was a bad question to ask :redface:

Reply 2096

D4rth

9

Original post by _HabibaH_

I though the R group was only affected if it was in a solution of excess acid/base, but at the isoelectric point only one amine/carboxyl group would exchange H+