OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

100cm3 because it was made up to 100cm3. atleast that's how i interpreted it

So I actually thought the sneakiest question on the whole damn paper was the electron configuration of Cu+, it's not like other configurations, because coppers normal config. is ...3d104s1 so Cu+ is ...3d10 did anyone put the same?

I got 2.12 as well. Not sure it's correct though :/

Does anyone think that there was a lot more AS stuff than normal in both F324 and F325 this year? Also do people think that that paper was harder than 2014 and 2015?

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I put Cu2+ ending 3d9
and Cu+ ending 3d10

Why was H+ not a catalyst!? I said it doesn't speed up the rate of reaction and is not reformed ?

i got 11.72, what did u get for the ph of the buffer of HNO2 i got 2.12?

How many marks was the electronic configuration

When I was doing it, it seemed hard.
Now that I'm out, it looks easy :/

Hopefully 85 is an A*

Lol at F321 in the paper tho

Then don't worry you got the marks
Apart from the even more obvious fact it was written on the reactant side not above the arrow like a catalyst both of your points are correct!

Here are questions topics I remember (Not in order):

Transition metals
Redox gold with CN-
Born haber* for K2SO4*
pH question - weak acid, buffer, Kw at 60°C
Kc for iodine question
k question, H+ catalyst, 4 step mechanism
Water of crystallisation

Nothing on fuel cells?

My numerical answers:
k=2.9e-2
H=-1099
Kc=104
pH=2.12, 3.43, 13.03, 10.76
Emf= 0.60V
X=4

Other stuff I remember writing:
- I2 is insoluble because it is non-polar and doesn't form hydrogen bonds
*
- Bidentate ligand donates 2 lone pairs to form 2 coordinate bonds

- Yellow precipitate with I- and AgNO3

- Entropy increases because of more moles and solid becomes aqueous

- Drawing a cell with platinum electrode and electrons/ions marked

The mechanism was weird, I had 2 steps as H+ +OH- becomes water

Hope it helps someone out there! Overall I think a similar paper to last year, maybe similar grade boundaries? Not sure.

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For buffer question I think you had to know that 1 mol of A- reacted with 2 moles H+. So instead of 0.04 mol HA you actually had 0.08 mol HA reacting with 0.05 mol A-. At equilibrium, the buffer would contain 0.03 mol HA and 0.05 mol A-. Plug that into the buffer ratio equation also using the Ka they gave you to work out H+ and then take -log(H+) to calculate pH. I got pH to be 3.55 to 2dp


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