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Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed)

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Depends on how many groups there are and in what positions they are in?

Phenol and methyl-benzene would have 4 different hydrogen environments

If there's more groups, then there would be way more than that, especially if it is not longer symmetrical

wait how would u label the H environments of phenol?
like this?
benzene h.png

Left or right?

Reply 1241

posthumus

Original post by Dolphino

Yeah I did. Basically you know around the methyl group, I thought that the two adjacent hydrogen atoms would be in the same environment since benzene is symmetrical. That environment plus the hydrogenl environment plus the hydrogen environment in methyl group makes three...

I'm a tad bit confused :colondollar:

So I thought I'd draw out what I had in mind...

Hope it's clear... I did the same thing with methyl-benzene. Made the methyl hydrogens' a part of 1 environment. So both phenol & methyl-benzene have 4 hydrogen environments?

Original post by StellaRawr11

wait how would u label the H environments of phenol?
like this?
benzene h.png

Left or right?

Left

Reply 1242

Dolphino

Original post by posthumus

I'm a tad bit confused :colondollar:

So I thought I'd draw out what I had in mind...

Hope it's clear... I did the same thing with methyl-benzene. Made the methyl hydrogens' a part of 1 environment. So both phenol & methyl-benzene have 4 hydrogen environments?

Left

Kk I see way I've done. It's just that I thought 3 and 4 would have the same environment

(edited 10 years ago)

Reply 1243

posthumus

Original post by Dolphino

3 and 4 should be the same environment though

Your not looking at the OH group... they are different distances away. How many hydrogen environments are in CH3CH2CH2CH2CH2OH ?

EDIT: Okay, glad you've got it now :smile:

Reply 1244

-strawberry-

Does anyone happen to have the January 13 paper that they could send me? :smile:

Reply 1245

AS01

Original post by -strawberry-

Does anyone happen to have the January 13 paper that they could send me? :smile:

http://www.freeexampapers.com/#A Level/Chemistry/Edexcel/2013 Jan
mark scheme: http://www.scribd.com/doc/126758041/Edexcel-GCE-Chemistry-Unit-5-MS

(edited 10 years ago)

Reply 1246

AtomicMan

Original post by posthumus

Your not looking at the OH group... they are different distances away. How many hydrogen environments are in CH3CH2CH2CH2CH2OH ?

EDIT: Okay, glad you've got it now :smile:

Is it 6?

Reply 1247

posthumus

Original post by AtomicMan

Is it 6?

Yes !

Reply 1248

blossomx

Hey.

You know with halogenation, does the FeBr3 catalyst simply polarise the Br2 molecule or can it also react like: FeBr3 + Br2 -> FeBr4- + Br+

Thanks. :smile:

Reply 1249

posthumus

Original post by LeaX

Hey.

You know with halogenation, does the FeBr3 catalyst simply polarise the Br2 molecule or can it also react like: FeBr3 + Br2 -> FeBr4- + Br+

Thanks. :smile:

Yup that sounds right to me! & then the FeBr4- will react with the extra Hydrogen (which has been substituted by the Br+) to form HBr and regenerate the FeBr3 catalyst :smile:

Reply 1250

-strawberry-

Original post by AS01

http://www.freeexampapers.com/#A Level/Chemistry/Edexcel/2013 Jan
mark scheme: http://www.scribd.com/doc/126758041/Edexcel-GCE-Chemistry-Unit-5-MS

Thank you so much! :smile:

Reply 1251

paddyroddy

Original post by StellaRawr11

Thanks AS01 :biggrin:

ok another qs that may come up x]

how many hydrogen environments should benzene have?
if it has substituents like OH or CH3, then what how many H environments does it have?

Thanks :biggrin:

as others have said phenol & methylbenzene (toluene) have 4 envionments

benzene itself has 1 because all 6 hydrogens are in the same environment

Reply 1252

paddyroddy

Original post by LeaX

Hey.

You know with halogenation, does the FeBr3 catalyst simply polarise the Br2 molecule or can it also react like: FeBr3 + Br2 -> FeBr4- + Br+

Thanks. :smile:

yeah your right, the reality is that ratehr than

FeBr3 + Br2 -> FeBr4- + Br+

its more like

FeBr3 + Br2 -> FeBr3.Br^(δ-ve)---Br^(δ+ve)

but the mark schemes accept both

Reply 1253

ayeswary

Original post by posthumus

Hopefully this will help you out...

I believe there should be HCl product also

EDIT: didn't see the fact that it was amino :tongue:

But I guess the group would just stay there... elimination will occur between H in the hydroxy group & chlorine

Thanks a lot. :smile:

Gud luck for your exams

Posted from TSR Mobile

Reply 1254

ayeswary

Original post by paddyroddy

2CH₃COCl + CH₃CH₂CH(NH₂)CH₂OH

Ethanoyl chloride reacts with both NH₂ & OH!

---> CH₃CH₂CH(HNOCCH₃)CH₂OOCCH₃ + 2HCl

Thanks a lot. Gud luck for your exams :smile:

Posted from TSR Mobile

Reply 1255

-strawberry-

Original post by TheUsername42

If you have any questions about the past papers you can directly ask chemistry university students who may already have done them (except 2013 ones) during their a-levels, visit www.thestudentsolutions.co.uk , hope this helps!

Ooh thank you :smile:

Reply 1256

blossomx

Original post by posthumus

Yup that sounds right to me! & then the FeBr4- will react with the extra Hydrogen (which has been substituted by the Br+) to form HBr and regenerate the FeBr3 catalyst :smile:

Original post by paddyroddy

yeah your right, the reality is that ratehr than

FeBr3 + Br2 -> FeBr4- + Br+

its more like

FeBr3 + Br2 -> FeBr3.Br^(δ-ve)---Br^(δ+ve)

but the mark schemes accept both

Thank you both. :biggrin:

Reply 1257

username644227

in june 11 q10
it says something on the increasing ph of the solutions
can anyone explain the concept behind this? quite confused on how you determine the magnitude of ph
increasing order= phenylamine < NH3 < butylamine
thanks :biggrin:

Reply 1258

jojo1995

Original post by StellaRawr11

High pH = alkaline/base

A base is something with the ability to attract a proton

in phenyl amine the nitrogen atom's lone pair of electrons is pulled into the ring of delocalised electrons and so the N atom is less electronegative and so has a weaker abiliuty to attract a proton - so only slightly basic

nh3 has a lone pair of electrons and so is able to attract a proton better than phenylamine as it nitrogen is electronegative so is quite basc

but, butylamine is even stonger .....the nitrogen has methyl groups surrounding it, they are lectron releasing and donate electrons to the nitrogen making it even more electronegative than usual, and so it can attract a proton the easiest and so is the strongest base.

It can't be nice down in hell - so i thought id help you out and try to make your day :smile:

(edited 10 years ago)

Reply 1259