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

Poll: How pumped up are you for this exam?-(warning)-(bad jokes arene this poll!)
"Titanium-I'm not going to corrode (even at high temperatures)" (A*) (22)
16.67%
"Benzene's my middle name, give me the paper in a week and I'll ace it!" (A) (27)
20.45%
"Yeah, I'm fairly electrophillic (positively charged) about the exam" (B) (27)
20.45%
"I'm in the middle of the salt bridge, but I will pass-eventually" (C) (21)
15.91%
"I'm feeling rather electroNegative about this exam" (D) (18)
13.64%
"Benzene, what's that?" (E) (6)
4.55%
"Chemistry, what's that?" (F) (11)
8.33%
This discussion is closed.
username644227
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#1241
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#1241
(Original post by posthumus)
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?
Name:  benzene h.png
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posthumus
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#1242
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#1242
(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 So I thought I'd draw out what I had in mind...

Name:  Phenolas.png
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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?
Name:  benzene h.png
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Dolphino
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#1243
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(Original post by posthumus)
I'm a tad bit confused So I thought I'd draw out what I had in mind...

Name:  Phenolas.png
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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?



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Kk I see way I've done. It's just that I thought 3 and 4 would have the same environment
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posthumus
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#1244
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#1244
(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
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-strawberry-
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#1245
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#1245
Does anyone happen to have the January 13 paper that they could send me?
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AS01
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#1246
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#1246
(Original post by -strawberry-)
Does anyone happen to have the January 13 paper that they could send me?
http://www.freeexampapers.com/#A Level/Chemistry/Edexcel/2013 Jan
mark scheme: http://www.scribd.com/doc/126758041/...stry-Unit-5-MS
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AtomicMan
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#1247
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#1247
(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
Is it 6?
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posthumus
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#1248
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#1248
(Original post by AtomicMan)
Is it 6?
Yes !
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LeaX
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#1249
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#1249
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.
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posthumus
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#1250
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#1250
(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.
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
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-strawberry-
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#1251
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#1251
Thank you so much!
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paddyroddy
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#1252
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#1252
(Original post by StellaRawr11)
Thanks AS01

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

benzene itself has 1 because all 6 hydrogens are in the same environment
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paddyroddy
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#1253
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#1253
(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.
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
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ayeswary
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#1254
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(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 But I guess the group would just stay there... elimination will occur between H in the hydroxy group & chlorine
Thanks a lot. Gud luck for your exams


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ayeswary
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#1255
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#1255
(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


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-strawberry-
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#1256
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#1256
(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
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LeaX
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#1257
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#1257
(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

(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.
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username644227
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#1258
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#1258
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
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jojo1995
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#1259
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(Original post by StellaRawr11)
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

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
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SKK94
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#1260
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#1260
If anyone's doing Unit 4 on 12th June, here is the thread
http://www.thestudentroom.co.uk/show....php?t=2308998
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