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

I think the simple definitions would be enough, so I wrote
sigma bond is direct overlap of orbitals and pi bond is sideways overlap of p orbitals

could you have also said that a pi bond has a lower bond enthalphy than a sigma bond, so it is weaker ?

Reply 1161

obeyyy

1

Original post by money-for-all

could you have also said that a pi bond has a lower bond enthalphy than a sigma bond, so it is weaker ?

this should be fine.

Reply 1162

samah786khan

4

For the electrophilic addition Q, I know i've got the right answers and wverything and I knew which of the products woukd be formed in greater abundance due to it being more stable, however just the exam stress got to me and i forgot how to name each one stupidly so for my description on which was formed more I drew and arrow to the compound that would be formed more and explained why and with the other i did the same and weote why itd be formed less! do you think i'll lose marks for that coz the q did just say draw the compounds?! Any thoughts? Thanku!

Reply 1163

Jitesh

14

For the first 6 marker I'm pretty sure it said draw one product then explain why you get two products and which would be the major one rather than two products in the mechanism...

I read it twice as well to confirm that

Reply 1164

MsDanderson

2

Original post by samah786khan

For the electrophilic addition Q, I know i've got the right answers and wverything and I knew which of the products woukd be formed in greater abundance due to it being more stable, however just the exam stress got to me and i forgot how to name each one stupidly so for my description on which was formed more I drew and arrow to the compound that would be formed more and explained why and with the other i did the same and weote why itd be formed less! do you think i'll lose marks for that coz the q did just say draw the compounds?! Any thoughts? Thanku!

You didn't need to name them, so don't worry. As long as you drew them out

Posted from TSR Mobile

Reply 1165

asinghj

16

Original post by Jitesh

For the first 6 marker I'm pretty sure it said draw one product then explain why you get two products and which would be the major one rather than two products in the mechanism...

I read it twice as well to confirm that

Draw both products
Mechanism for one

Reply 1166

samah786khan

4

Original post by asinghj

Draw both products
Mechanism for one

it was definitely draw 2 products and mechanism for 1

Reply 1167

oni176

7

What did people say for; "Why is this classified as sscondary alcohol" I said alkyl group attached on the second carbon. Will I get the mark? I know it should be two other carbons..
And why is this not a stereoisomer? question I put because the two groups attaches to the C=C bond is not on the same carbon.

And also what did people say for the volume, whether it will change or not as you go down the group?

(edited 7 years ago)

Reply 1168

oni176

7

Original post by samah786khan

it was definitely draw 2 products and mechanism for 1

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

Reply 1169

harry1208

7

Original post by oni176

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

It doesn't matter as long as you draw at least one mechanism and at least one product. I drew 2 mechanisms and 2 products, you won't lose marks for doing too much. :smile:

Reply 1170

harry1208

7

Original post by oni176

What did people say for; "Why is this classified as sscondary alcohol" I said alkyl group attached on the second carbon. Will I get the mark? I know it should be two other carbons..
And why is this not a stereoisomer? question I put because the two groups attaches to the C=C bond is not attached on the same carbon.

And also what did people say for the volume, whether it will change or not as you go down the group?

For the secondary alcohol, the answers is that it is connected to 2 alkyl groups. I put it is connected to 2 carbon groups, not really sure about my answer.

For the volume one I just looked at the formula, and used it to determine whether something was directly proportional to something else, and eventually got to volume. So I put that it will change (Not sure whether I put increase or decrease)

Reply 1171

456CJ

2

For the major I got 2-methyl-2-bromobutane and minor 2-methyl-3-bromobutane however I didn't name them but drew the skeletal formulae for both. Anyone else get this ?

Don't air me guys

Oni where u at my g

Original post by oni176

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

It definitely said draw 2 products, mechanism for one

Posted from TSR Mobile

Reply 1175

MsDanderson

2

Original post by 456CJ

For the major I got 2-methyl-2-bromobutane and minor 2-methyl-3-bromobutane however I didn't name them but drew the skeletal formulae for both. Anyone else get this ?