OCR Chemistry A Exam Thread (Breadth - May 27 2016 and Depth - June 10 2016)

Original post by help1208

guys if i got 44 in paper one and like 26 in paper 2 what grade is that?

Around a D

Reply 1181

Original post by oni176

No it said draw at least one product. I checked that couple of times.

I remember reading
Draw both products
Mechanism for one
Why one is formed more than the other

Reply 1182

help1208

Original post by Jitesh

Around a D

reckon i can take i to a B next year as we are all re-doing

Reply 1183

Ajan123

1

For the question on the oxidation equation for the secondary alcohol i wrote a Word equation. Would i still get the marks? I was unsure of the formula of the ketone.

Reply 1184

Original post by Jitesh

What m/z peak comes for 2-methylpropanoic acid but not butanoic acid?

None sadly.. All peaks work for both

Reply 1185

Original post by Ajan123

For the question on the oxidation equation for the secondary alcohol i wrote a Word equation. Would i still get the marks? I was unsure of the formula of the ketone.

It didn't specify what to use so you should be fine

Reply 1186

UK_Britain

2

Original post by asinghj

It didn't specify what to use so you should be fine

Yh it said write an Equation so I used the molecular formula for each one CxHxO+ [O]----> CxHxO +H2O

I don't know if I should draw a structural formula or what. Do you think I could still get the marks

Reply 1187

Original post by asinghj

None sadly.. All peaks work for both

I wrote 2-methylpropanoic acid but spent ages trying to work out what peak would be unique to it lol

What did it exactly mean by it forms a secondary carbocation? That confused me as I could see it was a carboxylic acid...

Reply 1188

Original post by UK_Britain

Yh it said write an Equation so I used the molecular formula for each one CxHxO+ [O]----> CxHxO +H2O

I don't know if I should draw a structural formula or what. Do you think I could still get the marks

As long as you used numbers instead of x, as in C4H10O and C4H8O then you should be fine

Reply 1189

Original post by Jitesh

I wrote 2-methylpropanoic acid but spent ages trying to work out what peak would be unique to it lol

What did it exactly mean by it forms a secondary carbocation? That confused me as I could see it was a carboxylic acid...

I wrote that peak at 43 only works with 2-methylpropanoic acid lol.

I think by secondary carbonation it means that the charge is on a carbon attached to 2 alkyl groups. If you draw the structure then replace the COOH with a + you will understand what I mean. I can't post pictures on mobile, don't know why.

Reply 1190

Original post by asinghj

I wrote that peak at 43 only works with 2-methylpropanoic acid lol.

I think by secondary carbonation it means that the charge is on a carbon attached to 2 alkyl groups. If you draw the structure then replace the COOH with a + you will understand what I mean. I can't post pictures on mobile, don't know why.

But it wasn't charged overall?? It would form a more stable structure being like that but I it didn't have an overall charge/wasn't an intermediate?

Reply 1191

Original post by Jitesh

But it wasn't charged overall?? It would form a more stable structure being like that but I it didn't have an overall charge/wasn't an intermediate?

I think that it gets charged by removing an electron, so the CH3CHCH3 + fragment ion would also be charged. If you draw the full structure the charge will be on the carbon with 1 bond broken.
Might be completely wrong but idk

Reply 1192

Original post by asinghj

I think that it gets charged by removing an electron, so the CH3CHCH3 + fragment ion would also be charged. If you draw the full structure the charge will be on the carbon with 1 bond broken.
Might be completely wrong but idk

Odd, never seen a statement like what it said in the exam before...

Hopefully the examiner is dopey and just sees the answer and gives me a solid 6

Reply 1193

Original post by Jitesh

Odd, never seen a statement like what it said in the exam before...

Hopefully the examiner is dopey and just sees the answer and gives me a solid 6

I hope for the same. Hopefully they ignore the statement about the peak at 43

Reply 1194

NotGambit

Original post by help1208

reckon i can take i to a B next year as we are all re-doing

You are redoing an AS paper which doesn't count towards your final grade? :O

Reply 1195

help1208

Original post by NotGambit

You are redoing an AS paper which doesn't count towards your final grade? :O

u do realise we are doing A2 with AS next yr again right for exams

Reply 1196

Original post by help1208

reckon i can take i to a B next year as we are all re-doing

Well yeah, or an A
How did you count the number of marks you had?

Reply 1197