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Chemistry of Natural Resources Salters OCR Jan '08

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for % by mass they didnt give Mr for Sulphur so i just used the figures provided and got like 70 something

does error carried forward also appy in these exams

Reply 21

Ahmato

And now I remember why I hate reading these sort of threads..Must have dropped about 10 marks already :banghead:

lol

tell me about it

Hi
They did give u the mass of sulphur, that periodic table they give u, what do u think thats 4.
They said copper ore 2, which is CuS they expect some diligence

Reply 24

unequivocally qualified

iamsuchatwat

Another 1, to oxidise the alcohol to the aldehyde, for 3 marks, u needed:
Acidified (1)
Potassium dichromate (VI) solution (1)
conditions:
heat, in a vertical condenser to distill off aldehyde (1)

DO NOT WRITE HEAT UNDER REFLUX! This would condense the aldehyde, and it would fall back in2 the reaction mixture. It would be oxidised AGAIN to a carboxylic acid.

it says on the york salters website powerpoint on alderhydes and ketones to heat under reflux with acidified potassium dichromate to make an aldehyde. so i dont think it matters whether you put it or not.

Reply 25

Namdeep

hw many marks was that question, the ore one 3?

Reply 26

temporary_username

Yes it does say that
But if u want 2 make an aldehyde, u add the dichromate to the alcohol not the other way around
alcohol = aldehyde = carb acid

a secondary alcohol can only be oxidised 1nce, it only has 1 H, so reflux it all u want, u need 2 specify tho

Reply 27

geriant89

If you look at previous past papers the answer scheme gives marks for:

Acidified (1) potassium dichromate solution (1) and heat under reflux (1)

for the calculation question i got 70 something percent but it said to round to 2 S.f, and didn't the question start off by saying: 'using the information in the.....'

in which case you didnt have to find the Mr of sulphur from the periodic table.

What did people get for the ' how many times more concentrated is the solution question'? think i messed tht one up.

Reply 28

unequivocally qualified

i think it came out at roughly 600!

Reply 29

temporary_username

Thats was easy
80/0.7

I got 350 something

for the people who wrote C16H31OH i think have got it wrong and will only get one mark for it or maybe i'm wrong lol, but i wrote C16H32O because in the mark scheme for January 2004 paper for natural resources it specifically says on question 4 c), its a similiar question, and the mark scheme states that (1 mark only for C10H17OH) and the answer for this specific question was C10H18O, so i think i got 2 marks for this lol, i knew i saw this question somewhere else before

Reply 32

geriant89

obviously wasnt that easy too completely different answers

Reply 33

temporary_username

4 give 4 not remembering the question, but I did find it easy
And anyway, I'd already got 84% in june with minimal revision, my A was guaranteed without lifting a pen. So 2 me its academical lol.
Anyway who doubts it, pm me and I'll add u 2 msn and send u a copy of my OCR grade certificate

Reply 34

kashkash786

what did people get for the copper(ii) ions reacting with powdered zinc? i know i've definitely got this wrong, i took an educated guess :smile:

lol

Reply 35

temporary_username

That was quite simple,
Copper ions oxidise zinc to Zinc ions. Mole ratio's of 1:1
Anyone who's doing chem for materials shud know this

Copper has a more positive E and zinc has a more negative 1.
Copper oxidises zinc/zinc reduces copper

Reply 36

unequivocally qualified

basically its Cu2+ +Zn goes to Zn2+ +Cu

Reply 37

unequivocally qualified

and iamsuchatwat theres no need to have that tone. some people a) may not be doing materials and b) may not have found it easy

Reply 38

Namdeep

iamsuchatwat is exactly wat his screenname says

Reply 39

temporary_username

Many people on this site r testament 2 the help I give them revising. I never bragged in this post or anything, but there's always some1 who doesn't like other people succeeding and that was the other user.
And I think if you look at the previous papers, this one was definitely the hardest Nat Resources for a few years.