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.
AS01
Badges: 2
Rep:
?
#1501
Report 6 years ago
#1501
(Original post by Lastminutepanic)
In the specification it says 'describe and carry out, where appropriate, the preparation of a compound, eg cholesteryl benzoate (a liquid crystal) and of methyl 3-nitrobenzoate, requiring some of the following techniques...' Do we need to know how to make cholesteryl benzoate and methyl 3-nitrobenzoate or just how to carry out the different techniques??
I think all we need to know is what all reactants has to be used
0
senz72
Badges: 16
Rep:
?
#1502
Report 6 years ago
#1502
Guys a question!

Can Ecell be negative?
Also Is H20 ligand smaller than OH-?

If not why is it Zn(H20)6 and Zn(OH)4? Why is there a decrease in coordination?

I'm so going to fail!
0
AS01
Badges: 2
Rep:
?
#1503
Report 6 years ago
#1503
(Original post by senz72)
Guys a question!

Can Ecell be negative?
Also Is H20 ligand smaller than OH-?

If not why is it Zn(H20)6 and Zn(OH)4? Why is there a decrease in coordination?

I'm so going to fail!
yes it can be. umm I think it is bigger than OH-
there is no decrease in coordination number sometimes they write [Zn(OH)4(H2O)2]2+ as [Zn(OH)4]2+
0
jojo1995
Badges: 2
Rep:
?
#1504
Report 6 years ago
#1504
(Original post by AS01)
no no just 3. The one marked with same colour are one H environment
thank you there was meant to be a cl on the last carbon ... so that would mean there were 5 right ?

(Original post by AS01)
if u look at the one which is projectiong out its in same environment as the one just below is coz they both are bonded to same group. Again if u look at another CH2 at the top plane t it is bonded to same groups as the one which is at the corner of the plane below. so they are in same environment
yeah i see that now thank you for all your help .... but why arent all 4 ch2s in the same h enviroment- thay are all attached to the same groups ?
0
senz72
Badges: 16
Rep:
?
#1505
Report 6 years ago
#1505
(Original post by AS01)
yes it can be. umm I think it is bigger than OH-
there is no decrease in coordination number sometimes they write [Zn(OH)4(H2O)2]2+ as [Zn(OH)4]2+
Does that mean it's partial ligand exchange? Why isn't it [Zn(Oh)6]4-?

Thanks.
0
AS01
Badges: 2
Rep:
?
#1506
Report 6 years ago
#1506
(Original post by jojo1995)
thank you there was meant to be a cl on the last carbon ... so that would mean there were 5 right ?



yeah i see that now thank you for all your help .... but why arent all 4 ch2s in the same h enviroment- thay are all attached to the same groups ?
lol! sorry! then yeah 5 environments
umm I think its coz those CH2s are not bonded to each other.
0
AS01
Badges: 2
Rep:
?
#1507
Report 6 years ago
#1507
(Original post by senz72)
Does that mean it's partial ligand exchange? Why isn't it [Zn(Oh)6]4-?

Thanks.
you can write that as well mark scheme does allow that but the correct one will be with Zn(OH)4. well if mark scheme allows then it doesnt mean they gave mark to incorrect one lol I think I am confusing you
All I mean is its Zn(OH)4 but MS does allow 6OH as people usually tend be to be like if Cr can form 6OH then this should as well and put it.
0
jojo1995
Badges: 2
Rep:
?
#1508
Report 6 years ago
#1508
(Original post by AS01)
lol! sorry! then yeah 5 environments
umm I think its coz those CH2s are not bonded to each other.


thank you
0
LeaX
Badges: 20
Rep:
?
#1509
Report 6 years ago
#1509
could someone please help with with jan 2012 question 10 and 11 in the multiple choice section.

for 10, i know the answer won't be A or C but i don't understand how you know which out of ch3coch3 and ch3cocl won't react? the answer is B.

for 11, i understand how they got the answer but i'm just wondering why doesn't phenylamine undergo sulfonation with dilute sulfuric acid? cos wouldn't the lone pair on N activate the ring? (similarly to how phenol reacts)

thanks
0
Knoyle quiah
Badges: 0
Rep:
?
#1510
Report 6 years ago
#1510
(Original post by AS01)
After u do steam distillation u have product with mixture of water and phenylamine right?
u wanna get rid of water so what u do is add NaCl and keep in separating funnel. I think aq layer will be below and organic layer at the top so u can get rid of aq layer by opening the tap. After than u have organic layer left which will still have water in it. So what u need to do next is add anhydrous Na2CO3 why this and not CaCl2 is coz CaCl2 and magnesium sulphate will react with phenylamine. So now water will be removed but then again u have sodium carbonate in ur product so u decant the product and then distil the solution to get phenylamine in pure form.
lol I think I explained more than what u asked for
Once again perfect explanation thank you so much, so adding nacl will make phenyl amine not dissolve in water and thats how the 2 layers form in the separating funnel right? but how come still some water left in the organic layer if tap was opened for aqueous layer?
0
AS01
Badges: 2
Rep:
?
#1511
Report 6 years ago
#1511
(Original post by jojo1995)
thank you
you welcome
0
AS01
Badges: 2
Rep:
?
#1512
Report 6 years ago
#1512
(Original post by Knoyle quiah)
Once again perfect explanation thank you so much, so adding nacl will make phenyl amine not dissolve in water and thats how the 2 layers form in the separating funnel right? but how come still some water left in the organic layer if tap was opened for aqueous layer?
u dont let all water go purposefully coz if u do then there is a danger that some of ur product leaving along with water which will reduce the yield
0
AS01
Badges: 2
Rep:
?
#1513
Report 6 years ago
#1513
(Original post by LeaX)
could someone please help with with jan 2012 question 10 and 11 in the multiple choice section.

for 10, i know the answer won't be A or C but i don't understand how you know which out of ch3coch3 and ch3cocl won't react? the answer is B.

for 11, i understand how they got the answer but i'm just wondering why doesn't phenylamine undergo sulfonation with dilute sulfuric acid? cos wouldn't the lone pair on N activate the ring? (similarly to how phenol reacts)

thanks
Its coz acyl chloride does react with NaOH. for 11 what happens is acid reacts with NH2 and forms NH3+ so this means the ring will be deactivated
0
JRP95
Badges: 2
Rep:
?
#1514
Report 6 years ago
#1514
(Original post by AS01)
After u do steam distillation u have product with mixture of water and phenylamine right?
u wanna get rid of water so what u do is add NaCl and keep in separating funnel. I think aq layer will be below and organic layer at the top so u can get rid of aq layer by opening the tap. After than u have organic layer left which will still have water in it. So what u need to do next is add anhydrous Na2CO3 why this and not CaCl2 is coz CaCl2 and magnesium sulphate will react with phenylamine. So now water will be removed but then again u have sodium carbonate in ur product so u decant the product and then distil the solution to get phenylamine in pure form.
lol I think I explained more than what u asked for
Do we have to know all of this and the last post for the exam?!
0
AS01
Badges: 2
Rep:
?
#1515
Report 6 years ago
#1515
(Original post by JRP95)
Do we have to know all of this and the last post for the exam?!
yes we do
what we need to know is how steam distillation works
0
JRP95
Badges: 2
Rep:
?
#1516
Report 6 years ago
#1516
(Original post by AS01)
yes we do
what we need to know is how steam distillation works
Hmm I'd take a gamble and not bother then, a big steam distillation question already came up a couple of years ago so they'll probably do something on recrystallisation/reflux/fractional distillation.

Also we don't need to know about all that stuff you said after the steam distillation?
0
AS01
Badges: 2
Rep:
?
#1517
Report 6 years ago
#1517
(Original post by JRP95)
Hmm I'd take a gamble and not bother then, a big steam distillation question already came up a couple of years ago so they'll probably do something on recrystallisation/reflux/fractional distillation.

Also we don't need to know about all that stuff you said after the steam distillation?
lol okay
we do its about purifying ur products which they can ask for any type of reaction
0
SKK94
Badges: 1
Rep:
?
#1518
Report 6 years ago
#1518
The C=O in esters does not react with Brady's reagent right?
0
posthumus
Badges: 20
Rep:
?
#1519
Report 6 years ago
#1519
(Original post by SKK94)
The C=O in esters does not react with Brady's reagent right?
Nope they don't
0
SKK94
Badges: 1
Rep:
?
#1520
Report 6 years ago
#1520
(Original post by posthumus)
Nope they don't
Thanks

Another doubt:
Phenylamine dissolves in aqueous acids because it forms an ionic salt (and they are more soluble in aq. acids than in water)
^Does this apply to alkyl amines as well?

I have similar doubts to yours in the transitions chapter. I'm still trying to figure them out :/
0
X
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Bristol
    Undergraduate Open Afternoon Undergraduate
    Wed, 23 Oct '19
  • University of Exeter
    Undergraduate Open Day - Penryn Campus Undergraduate
    Wed, 23 Oct '19
  • University of Nottingham
    Mini Open Day Undergraduate
    Wed, 23 Oct '19

Have you made up your mind on your five uni choices?

Yes I know where I'm applying (157)
59.47%
No I haven't decided yet (61)
23.11%
Yes but I might change my mind (46)
17.42%

Watched Threads

View All