[Josh1993]

(Original post by WrongSideUp)
For Acid/salt... Which value did you use for the acid and how did you get it?

mol(NaOH) = 10*10^-3(0.125) = 1.25*10^-3
Mol(HX) = 15*10^-3(0.174) = 2.61*10^-3
Mol ( x-) = 1.25*10^-3
mol (HX) after reaction 2.61*10^-3 - 1.25*10^-3 = 1.36*10^-3
[H+] = ka [acid]/ [conjugate base] use mols as volumes cancel
[H+] = (3.01*10^-5) ( 1.36*10^-3 / 1.25*10^-3)
= 3.27*10^-5 moldm^-3

PH = 4.48

[georgerapley]

(Original post by Josh1993)
Unofficial mark scheme.

1a)

i)0.47,0.170
ii)sraightforward.
iii)equal amount of mols on both sides.
iv)52.1

b)

i) D
ii)B
iii)A
iv)C

2) 4.5*10^-4
4.5*10^-3
4.33*10^-2

b) rate = 4.44 mol^-2dm^6s^-1

a) proton donor.

b) i) ii) iii) BBAABA in that order.

c) 37.8 cm^3

d) i) 4.52
ii) standard
iii)2.64
iv)4.48.

4 a) mechanism as standard (methylpropanoate)
b) i)1,5-pentanediol
ii) simple enough.
iii) base hydrolysis (base is usually ignored). acts as nucleophile blah blah

c i) ethanoic acid
ii)not sure.nucleophyllic addition-eleimination.
iii) no HCl , not as vigourous etc....

d) can't draw

e) i ) ester
ii) i count 10 but think i may be wrong.
iii) look at formula sheet.

f) i) 2nd one and last one( not sure again)
ii) pink ------> colourless

5) a)Nuclephyllic addition.
B)2-Bromobutanenitrile
c) NH3 , Excess , nucleophyllic substitiution.
d i) zwitterion
ii) stronger forces of attraction , Vdw in the other molecule etc....

e) i) NH2CH2COOCH2CH3
ii) COH(CH3)2CONH2
iii) NH2CH2CH2CH2COOH
iii) CH3CH2CH(N(CH3)2)COOH hard without drawing

6 a) AlCl3 + CH3COCl -----------------> [AlCl4]- + CH3CO+
AlCl4 - + H+ ---------------> AlCl3 + HCl
Phenylethanone

b) C6H5CO+
c) Inductive effects?? I should really know this but oh well.

7 a) propan-1-ol conc H2SO4 orange-----> green
propanal , fehlings/tollens , brick red PPT, silver mirror
propanoic acid , Na2CO3 , Effervesence(CO2)
Chloropropane , dil HNO3 , NaOH , AgNO3, white PPT

b) oxidation, state wavenumber of c=o,diffrent affinites/solubilities.

8) 1,4 dinitrobenzene
1,2 dinitrobenzene

double bond with 4 methyl groups around it.
cyclocompund (cyclohexane)

c=o on benzene
aldehyde on benzene.


3 ethyl groups as bonded to N.
c(CH3)3NHCH3

Feel free to amend and add to this as some questions I dont know (only a couple). This is very rushed so likely to be mistakes.

amendment:

4eii) 12 peaks

[Strangeclouds]

(Original post by lamalas600)
You've done the exam now, so how will it help?

If you don't want to see it, don't come on this thread.

Otherwise hush up

[Josh1993]

(Original post by georgerapley)
amendment:

4eii) 12 peaks

would you mind showing me how you get that, not saying you are wrong im just kepp counting 10.

[lamalas600]

(Original post by Strangeclouds)
If you don't want to see it, don't come on this thread.

Otherwise hush up

I'm trying to help people, there's no point looking at an exam you've done, you really should concentrate on the other exams your doing

[Josh1993]

(Original post by lamalas600)
I'm trying to help people, there's no point looking at an exam you've done, you really should concentrate on the other exams your doing

I have to agree. Your other exams are a bigger priority.

[lamalas600]

(Original post by Josh1993)
I have to agree. Your other exams are a bigger priority.

Hehe fair point

[WrongSideUp]

(Original post by lamalas600)
You've done the exam now, so how will it help?

Because I want to know what it was? Arguing about being on this thread on this thread is not going to get us anywhere. Didn't take me a minute to get an answer and solve it but I find myself coming back to reply to you, lol.

[Strangeclouds]

(Original post by lamalas600)
I'm trying to help people, there's no point looking at an exam you've done, you really should concentrate on the other exams your doing

My next exam isn't requiring my immediate attention, so you know, actually I'll just try and gauge how I did on this.
Also, don't those rules apply to yourself?

[lamalas600]

(Original post by WrongSideUp)
Because I want to know what it was? Arguing about being on this thread on this thread is not going to get us anywhere. Didn't take me a minute to get an answer and solve it but I find myself coming back to reply to you, lol.

Sorry

[Josh1993]

(Original post by lamalas600)
Hehe fair point

c3 tommorow edexcel. :

[lamalas600]

(Original post by Strangeclouds)
My next exam isn't requiring my immediate attention, so you know, actually I'll just try and gauge how I did on this.
Also, don't those rules apply to yourself?

Sorry

[Strangeclouds]

(Original post by lamalas600)
Sorry

aha no worries bro, best of luck for all your exams.

[lamalas600]

(Original post by Strangeclouds)
aha no worries bro, best of luck for all your exams.

Good luck to you to 5 left

[Josh1993]

(Original post by jackbanner)
5 peaks from the two benzenes to the central carbon (carbon with the single bond to the oxygen)...then the rest of the carbons form its own peaks

yep , thank you.

[TL1]

So does the edexcel chemistry paper not come out til tomorrow? Because of international students?

[Evanesyne]

How did everyone find the paper? Harder/easier/about the same compared to previous years?

After reading everyone's answers: Gap year here I come....

[NeuralGroove]

(Original post by Josh1993)
Unofficial mark scheme.

1a)

i)0.47,0.170
ii)sraightforward.
iii)equal amount of mols on both sides.
iv)52.1

b)

i) D
ii)B
iii)A
iv)C

2) 4.5*10^-4
4.5*10^-3
4.33*10^-2

b) rate = 4.44 mol^-2dm^6s^-1

a) proton donor.

b) i) ii) iii) BBAABA in that order.

c) 37.8 cm^3

d) i) 4.52
ii) standard
iii)2.64
iv)4.48.

4 a) mechanism as standard (methylpropanoate)
b) i)1,5-pentanediol
ii) simple enough.
iii) base hydrolysis (base is usually ignored). acts as nucleophile blah blah

c i) ethanoic acid
ii)not sure.nucleophyllic addition-eleimination.
iii) no HCl , not as vigourous etc....

d) can't draw

e) i ) ester
ii) i count 10 but think i may be wrong. it is 12
iii) look at formula sheet.

f) i) 2nd one and last one( not sure again)
ii) pink ------> colourless

5) a)Nuclephyllic addition.
B)2-Bromobutanenitrile
c) NH3 , Excess , nucleophyllic substitiution.
d i) zwitterion
ii) stronger forces of attraction , Vdw in the other molecule etc....

e) i) NH2CH2COOCH2CH3
ii) COH(CH3)2CONH2
iii) NH2CH2CH2CH2COOH
iii) CH3CH2CH(N(CH3)2)COOH hard without drawing

6 a) AlCl3 + CH3COCl -----------------> [AlCl4]- + CH3CO+
AlCl4 - + H+ ---------------> AlCl3 + HCl
Phenylethanone

b) C6H5CO+
c) Inductive effects?? I should really know this but oh well.

7 a) propan-1-ol conc H2SO4 orange-----> green
propanal , fehlings/tollens , brick red PPT, silver mirror
propanoic acid , Na2CO3 , Effervesence(CO2)
Chloropropane , dil HNO3 , NaOH , AgNO3, white PPT

b) oxidation, state wavenumber of c=o,diffrent affinites/solubilities.

8) 1,4 dinitrobenzene
1,2 dinitrobenzene

double bond with 4 methyl groups around it.
cyclocompund (cyclohexane)

c=o on benzene
aldehyde on benzene.


3 ethyl groups as bonded to N.
c(CH3)3NHCH3

Feel free to amend and add to this as some questions I dont know (only a couple). This is very rushed so likely to be mistakes.

Amendment:

8) The C=O was on cyclohexane, obviously with two hydrogen atoms removed from that carbon, not benzene.
The aldehyde group was a CHO attached to a carbon from cyclopentane, using benzene or cyclohexane would mean that the carbon atom had far too many bonds.

6)c. Methyl group has a positive inductive effect, concentrating electron density in the delocalised electron ring, making forces of attraction between that and the electrophile stronger, etc...

7)a. You've not mentioned that acidified potassium dichromate is used, and that causes the colour change.

4)f.ii. I wasn't certain so I just double checked, but phenolphthalein changes from colourless to red/purple/pink.

[Picture~Perfect]

(Original post by lamalas600)
I'm trying to help people, there's no point looking at an exam you've done, you really should concentrate on the other exams your doing

A lot of people like to take the time to go over a paper and estimate the grade they might achieve. For me it helps me get closures and allows me to clear my head and move on to other exams. If thats not the kind of person you are then fine, but don't tell other people what they should or shouldn't do. It can be helpful to go over questions from a paper, its nice to find out that you got the same answer as others, it confirms that you were doing the right thing.

[Liyanajamain]

for 7b for "suggest a chemical process that mightve led to contamination of propan-2-ol with propanone" is it okay to say extraction of crude oil?
i wanted to write oxidation but it felt more like a "reaction" than a "chemical process" ? idk

and can someone link me to the revision thread for unit 4 ?