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Reply 20
Salters chem of materials today was sooooo hard...and this one was spose to be the better out of the 2... uh oh...
Reply 21
Food Science (Nuffield Special Study) was pretty good I thought. The last section was on the last chapter and obviously therefore required major bull%^&*ing. Most people at my centre (myself included) had no clue what slash and burn even is, never mind what the question was.

Apart from that a) and b) were simple and c) was nothing too tricky. Should be ok.
Reply 22
SFC_FOREVER!
The one about undiluted etc.. I got 0.09mols. Dont ask me how I got there :biggrin:
I think I got that too, something like that. I think it might have been 0.9 for undiluted

The person that said it didn't test many areas was totally right. I feel cheated, I learnt so much random stuff and it didn't come up. There was practically nothing on the steel story, except flippin complexes. Was the Fe complex with a coordination no. of 6, assuming the ligands were bidentate? meh. I thought so.

I liked the calculations for once, it's just those flipping recall things like "what ion is red coloured" hmm ^o)
It was me that said about them testing just one subject:rolleyes: As you can tell, I dont really like Salters. This was a retake from January, and in both papers only tiny amounts of the steel stroy has come up. How is this fair? Todays paper was horrible I thought.
Reply 24
SFC_FOREVER!
It was me that said about them testing just one subject:rolleyes: As you can tell, I dont really like Salters. This was a retake from January, and in both papers only tiny amounts of the steel stroy has come up. How is this fair? Todays paper was horrible I thought.
I did it in january and a lot of the steel story came up then, in terms of half cells and the last page was all about the basic oxygen process. I did so badly then :s:
Reply 25
salters chemistry was really hard, i thought......there was no half cells or anything like that, and that ligand one confused me... i couldn't draw it properly!! anyone remember any other answers they got? :smile:
Saffie
I did it in january and a lot of the steel story came up then, in terms of half cells and the last page was all about the basic oxygen process. I did so badly then :s:


Yeh true, forgot about the half cells. I got 22/90 in January. I don't expect to do any better now!
Edexcel Chemistry Unit 4 & 5 were surprisingly easy. I liked both papers...Something tells me this is going to be another killer synoptic paper. The practicals were rather easy too...they're going to drop a bomb on the 26th...
Hmm it was... 20.1cm^3 0.02moldm^-3 KMnO4 was needed to complete 20cm^3 of 6g of tablet made into 200/250cm^3 of solution.

The equation was a 1:5 ratio of KMnO4-Fe(II)?

Anyone care to have a go...

I actually think my answer was 37.2...rounded up to 37.3 so it could be i had half the actual answer, or something.
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For the AB rate determining step question what did you put?

I put SN1 and put that the rate determining step depended on the conc of B. But that doesn't sound good to me, as the orders were 1 and 2(?) and SN1 involves 1 and 0. But it couldn't be sN2 as that doens't havea rate determining step and i couldn't think of any other relevant mechanisms.
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And the bit about reactivity of the acid chloride, what did people put there?
Reply 29
uk6458
salters chemistry was really hard, i thought......there was no half cells or anything like that, and that ligand one confused me... i couldn't draw it properly!! anyone remember any other answers they got? :smile:
I remember the "why are polymers brittle when they get to the glassy state", kinda rambled bout coldness and less energy to overcome intermolecular forces.
Fe3+ (aq) + 2OH- (aq) --> Fe(OH)2 (s) - hope that was right
red ion? I made that up, I said Cr2+ I think :redface:
how to replicate DNA- unzips (H bonds break) to form mRNA in nucleus from free nucleotides
shape of DNA- helix. Thing ommited in formation- H2O.
heterogeneous + homogenous catalysts :yy:
PEN higher MP than PET- more functional groups, more Pd-Pd bonds
describe potassium manganate titration
describe paper chromatography
describe collecting O2 in H2O2 experiment.

they did ask quite a lot..
Reply 30
SFC_FOREVER!
Yeh true, forgot about the half cells. I got 22/90 in January. I don't expect to do any better now!
wow that's bad:smile: I got 46. Did quite a few past papers, hopefully brought it up to a B *prays*
It was not substitution as there was only one product. So it was addition. I just said it was electrophilic addition and the addition of B molecules to A was the rate determining step.

Reactivity of acid chloride? Did i miss something?
Saffie
I think I got that too, something like that. I think it might have been 0.9 for undiluted

The person that said it didn't test many areas was totally right. I feel cheated, I learnt so much random stuff and it didn't come up. There was practically nothing on the steel story, except flippin complexes. Was the Fe complex with a coordination no. of 6, assuming the ligands were bidentate? meh. I thought so.

I liked the calculations for once, it's just those flipping recall things like "what ion is red coloured" hmm ^o)


I got 0.91 for the undiluted.
I put a coordination number of 3, but then drew it with bidentate ligands, so I've screwed up one of those things :s-smilie:
Erm, what else... Didn't like the question about why lowering tg made polymers brittle (Yeah, simple I know, but I went blank.)
The last one was a bit weird too. Quite liked it, because I knew it all from biology. It didn't seem very chemically at all.
Oh, didn't like writing the titration procedure. Didn't know enough detail for 6 marks. It was the self indicating, pink one though, right?
Sounds good to me hakking. Mine was just a wild stab, and i phrased my second part about what actually causes the rate determining step so it was independant of my mention of SN1.

After the question asking for the ester to be drawn out it said why does the reaction happen without a catalyst or heat. Because COCl makes the carbon positive and susceptible to nucleophilic attack moreso than COOH. Or I suppose it could have just been about lower Ea, but that'd be lame.
Reply 34
For the mechanism one it didn’t have to be a known mechanism, you just had to invent one that corresponded with the rate equation and the stoicheometerical equation, and I think the rate determining step was one where A + A + B reacted (as showed by the rate equation) Rate = k[A2]
Well the papers cudnt have been better....
It was surprise to know that the papers were easy compared to the previous years(Raoults and other laws. They didnt even gave us any graphs in interpret) I think i did quite well in 4 and 5. I think i messed up the AB mechanism thing in unit 5. I wrote the mechanism was SN2 and had an intermediate(A + B = A-----B = AB) Wht do u think was the right answer?
Also i got the Fe % as 74.5 which is quite rights as most of the guys got that (and it seems reasonable as well)
Unit 4 i got Kc as 0.49 atm or something(cant remember)
I think they r not gonna let us get away that easily...they r gonna strike on 26th with synoptic.......... I just hope that it comes as a peice of cake as these did...
Hope everyone had a good paper.......
And best of luck in synoptic.
Reply 36
on the nmr q, where you had to identify the "mystery alcohol" , what did you get? think i put methanol......:confused:

i put cordination no as three aswell.....damm.....how many marks was that question? :frown:
GAH someone tell me how they got 74.5% I've been trying for a while, it's frustrating.

SN2 has no rate determining steps.

Prometheus' idea seems a good one.

If i did as well as i calculated (80%) I'll only need 55% synoptic.
Reply 38
moles of KMnO4 = 20.1/1000 x 0.02 = 4.02 x 10^-4
5:1 ratio so x5 = 2.01 x 10^-3 moles of Fe compound
sampled from 200cc so x 8 = 0.01608 moles

theoretical moles = mass/relative molecular mass
=6/278 = 0.02158

0.01608/0.02158 = 74.5%
Aha! I multiplied by 4 instead of 8.

Drop 1 or 2 marks out of 5? Everthing else was otherwise correct, consequently i got half the right answer.

That's cheered me up a little bit.

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