[i'm no superman]

(Original post by Hasan)
That was a really hard paper. For Jan 08, 40/60 was an A and for June 08 it was 44. This was harder than both so I think 40 might be an A.

For the reaction between 4-methylphenol and aqueous bromine, where did the bromine go? I put two, one on the second carbon and one on the 6th carbon. Also, was the answer for what reagent makes benzoic acid go to benzenemethanol LiAlH4?

Yeah I got exactly the same answers as you there.

I'm really hoping the grade boundary stays the same as it was back in Jan '08. The paper certainly wasn't easy to the extent for an A to be anything over 44/60. It had a lot of calculations and follow up questions from those questions.

Where the concentrations 0.025 and 0.075 or did I have to do something else with them?

My formula was something like CH3CH2COOH + NaOH -> CH3CH2COO-Na+ + H2O and then I just did 10/40 x 0.1 = 0.025 and 30/40 x 0.1 = 0.075 to get the concentrations...how many marks out of 3 would I have got for that?

[mittal1989]

(Original post by BaptistJohn)
there was a test between the aldehyde and alcohol, but what was the second test? was it like the carboxylic acid and the aldehyde? because i remember putting sodium hydrogen carbonate and 'fizzing/bubbling', would that be right?

yup thats what i wrote

[dersire3]

(Original post by mittal1989)
yh yh i got the same second part for congo red. The top one was about how each colour happens in inidcators. i dint get 4.41 alot of ppl got that. i think its coz i got the concentration of base wrong. i got 0.01 for base i think. buh 0.075 for acid. So that shud get me some marks right ?

pH red was 5 and 3 was violet
concentration of propanoic was 0.075 and naoh was 0.025
i got 179 for activation energy and remember kc as 5.88
i said that you dont need to know volume because moles=conc times volume over thousand, reaarnage each to get conc and when didvining the volumes cancel so they aint needed

[Papaya]

(Original post by dersire3)
i said that you dont need to know volume because moles=conc times volume over thousand, reaarnage each to get conc and when didvining the volumes cancel so they aint needed

I kind of implied that - I said all reactants and products were in liquid state, so the total volume does not change.

[dersire3]

(Original post by Papaya)
I kind of implied that - I said all reactants and products were in liquid state, so the total volume does not change.

what u get for kc value

also why can acyl chloride not be reversible?
i wrote cause hcl cannot act as a nucleophile like water can so no backwards reaction can occur!

[Papaya]

(Original post by dersire3)
what u get for kc value

also why can acyl chloride not be reversible?
i wrote cause hcl cannot act as a nucleophile like water can so no backwards reaction can occur!

I got that Kc value wrong anyway

Eeer... I said that no stable ion can be formed when the H-Cl bond is broken, so the nucleophile attacks to bring the reaction to an end, unlike the COOH group, where a stable COO- ion can be formed. Not sure whether that's right, though.

[dersire3]

(Original post by Papaya)
I got that Kc value wrong anyway

Eeer... I said that no stable ion can be formed when the H-Cl bond is broken, so the nucleophile attacks to bring the reaction to an end, unlike the COOH group, where a stable COO- ion can be formed. Not sure whether that's right, though.

ph 5 was red
ph 3 was violet

[thegodfather7]

it didnt ask why can acyl chloride not be reversible did it?

[dersire3]

kc values people!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!1

[thegodfather7]

kc = 4

[dersire3]

(Original post by thegodfather7)
it didnt ask why can acyl chloride not be reversible did it?

yh it said y did acyl chloride go to completion hence not reversible

dogfather what ur kc value?

[Papaya]

(Original post by thegodfather7)
it didnt ask why can acyl chloride not be reversible did it?

The first part asked why it reached completion and the second part said explain why it was more vigorous than the carboxylic acid, I think

[dersire3]

(Original post by thegodfather7)
kc = 4

dam i had a feeling i was wrong, i got 5.88

[thegodfather7]

dont think it did say that, but neway my kc was 4, urs?

[dersire3]

mine was 5.88

[thegodfather7]

yer, what is the right answer ? isit 4?

[dersire3]

(Original post by thegodfather7)
yer, what is the right answer ? isit 4?

so far only know your answer and mine so no idea, im trying to get others to write answers aswell, dw soon will find out

btw check other unit 4 forum, the paper is up, can u send it to me please

[mittal1989]

(Original post by dersire3)
so far only know your answer and mine so no idea, im trying to get others to write answers aswell, dw soon will find out

btw check other unit 4 forum, the paper is up, can u send it to me please

the paper is up howw show me send it my way plz

[mittal1989]

kc is defo 4.01
the indiicator question i cant remember the colours buh when more alkali added it shifts to the right releasing In- so u get more of the colour of ph5 and when acid added the equilibrium shifts to the left so u get colour of ph3

[mittal1989]

(Original post by Papaya)
I kind of implied that - I said all reactants and products were in liquid state, so the total volume does not change.

all you had to write for that one is volumes cancel when concentrations calcuated so it makes no difference