Think the marks schemes left out the question on that proton nor where you had to determin the structure and you where given the integration values in the table.

Reply 1186

wannabeme

Originally by TheBigDog, amended too many times to mention everyone...

1a) rate - 14.4x10^-3, Q - 0.1, P - 0.30 (3)
b) rate constant and units - 0.15 mol-2dm+6s-1 (3)
c) exponential graph - G (1) 7 marks

2a) sufur trioxide = 5.2 (1)
dioxide - 2.8 (1)
b) Kc = [O2][SO2]^2/[SO3]^2 (1)
c) 0.0338 (3)
d)i) increased (1)
ii) no effect (1)
e) higher temperature was T1, T2 had to be lower because Kc fell, which meant products fell. Backward was exo so a fall in temp would increase exo reactants. (3) 12 marks

3a) proton acceptor (1)
b) CH3CH2NH2 + H2O --> CH3CH2N+H3 + OH-
b) ii) As the ammonium ion can dissociate easily in equilibrium/ only partially dissociates in water
c) ethylamine stronger, inductive effect of alkyl group increases availability of lone pair on N to accept a proton (3)
d) NH3 / CH3CH2N+H3Cl / ? (1)
e) NH3 + H20 -> NH4+ + OH- reacts with ethylamine from the solution, which in turn makes the ethyl ammonium salt so concentration of H+ stays same due to shift of equilibrium position
adding H+ makes H20 with OH ions, equilibrium shifts right to replace the OH ions (2) 10 marks

4a) pH = 0.177 (2)
b) partially dissociates Ka = [H+][OH-] / [HX]
c) Ka = 3.09 x 10^-5 (3)
d) pH = 12.94 (6) 12 marks
5a) H. (1)
b) CH3.(1)
c) peak 29 = CHO. and CH3CH2. (2)
c) ACDB (4)

6a) OH (1)
bi) RC(=O)CH2RR (?)
ii) CH3C(=O)R (?)
iii) RC(OH)(CH3)2 (?)
c) CH3C(=O)CH2C(OH)(CH3)2 (?) total marks?

7a) Heat breaks down peptide link to form non-sweet amino acids, gets rid of flavour
b) 2-amino- 1,4 butandioic acid , don't need 1, 4 (1)
c) high pH = COO- *on both COOH groups* (1)
d) zwitterions (1)
c) stereoisomer – same structural formula, arranged differently in space (2)
ii) pair of optical isomer will rotate plane polarized light different directions (2) 7 marks

8a) 3 uses = soap (sodium salt), biodiesel (methyl ester), cationic surfactant / fabric softener
(quaternary ammonium ion) (3)
b) common name and type = terylene and polyester (2)
Kevlar or any Nylon and polyamide (2)
c) polyamide has hydrogen bonds, polyester just has van der wals (2) 9 marks

9a) many possible equations, HNO3 + H2SO4 = H20 + NO2+ + HSO4-
Both concentrated (3)
b) mechanism (3)
c) Cmnr = 5 (1)
Hnmr = 2 (1)
d) 2C7H5N3O6-> 7CO + 7C + 5H2O + 3N2 (1) 9 marks

10a) nucleophilic addition elimination made propanimide (6)
b) nucleophilic substitution made primary amide of propylamine (6)
c) electrostatic repulsion (because NH3 has a lone pair and is attacking an electron-rich ring The delta positive will be delocalised into the ring, making the carbon less prone to nucleophilic attack (1) 13 marks

11. propan-2-ol and propene (2)
Step 1 = NaBH4 and nuc. addition (2) (or LiAlH4)
Step 2 = conc phosphoric acid / conc H2SO4 and elimination (2)
Step 3 = HBr and electrophilic addition (2) 8 marks

Not too sure of ones in bold, will someone check?

with updated 6

Reply 1187

wibletg

Original post by Vinz93

the something being ACDB. maybe u misheard or its hazy in your memory now? Many people on this forum have posted with ACDB. :s-smilie:

the middle CD seems right to me but I can't remember for the life of me what I put, whether it was AB or BA :s-smilie:

*nmr

Question 6)

a) OH

b) RCOCH

c) RCOCH

d) RCH3

e) 4 hydroxy 2,2 dimethylbutan2one

Reply 1190

juliewho

On the markscheme for 6a), did we have to write O-H (alcohol)? Because there are O-H (acid) too

Reply 1191

Chemteacher

Original post by Chemteacher

Question 6)

a) OH

b) RCOCH

c) RCOCH

d) RCH3

e) 4 hydroxy 2,2 dimethylbutan2one

Total Marks 5

Reply 1192

Yosemite80

Original post by wibletg

the middle CD seems right to me but I can't remember for the life of me what I put, whether it was AB or BA :s-smilie:

It's ACDB, I remember I checked and verified in the exam that A was first and C was second. Drew the fragment lines across the bonds with the m/z value of the leftover bit written beside them, lol

Reply 1193

Vinz93

with stereoisomer, i think you can have same molecular formula too

and 6a) will be very specific...OH (alcohols)

Reply 1194

Yosemite80

Original post by juliewho

On the markscheme for 6a), did we have to write O-H (alcohol)? Because there are O-H (acid) too

Yes. I suspect alcohol will be underlined specifically in the mark scheme as usual

Reply 1195

Chemteacher

Original post by juliewho

On the markscheme for 6a), did we have to write O-H (alcohol)? Because there are O-H (acid) too

I would have told my kids to put alcohol at the end, but not too sure what the examiner would say after all an OH is the functional group

Reply 1196

handsome7654

Original post by Chemteacher

Question 6)

a) OH

b) RCOCH

c) RCOCH

d) RCH3

e) 4 hydroxy 2,2 dimethylbutan2one

****! You had to name the molecule?!! I don't think I named it! :mad:

Reply 1197

Chemteacher

Original post by Yosemite80

Yes. I suspect alcohol will be underlined specifically in the mark scheme as usual

Agreed

Reply 1198

Shalo1

What was question 5! It's really bugging mee :frown:

Reply 1199

freddy

Original post by Manii93

Probably 1 or 2 marks below average since the alkaline buffer seems to have thrown a lot of people off (well people in my school thought so anyway), but generally it was standard with a hint of 'weirdness'. :biggrin: