ocr a f325 revision thread

I think I got 0.0448
I have no idea where the range will be, because I've seen all sorts of answers from 0.02-0.05

Don't take my word as gospel for the CO2 question. I'm only a student too.

Going to oxbridge .
Are you confident of full marks so far?

No, on that CO2 question I forgot to multiply by 6. However, although I won't get 100/100 raw, I could have got 150/150 ums.

No, on that CO2 question I forgot to multiply by 6. However, although I won't get 100/100 raw, I could have got 150/150 ums.

For the table with concentration changes, was it the Iodine that had its concentration increased?

If so, I put HI to increase and hydrogen to decrease, and Iodine to have increased, in order to keep the value of Kc constant.

If you think about it, Kc is constant, increasing Iodine increase the bottom of the fraction, so the value of the Kc expression decreases. We need to increase it again, so we need to increase the top and decrease the bottom, so HI rises, Hydrogen decreases, and Iodine decreases relative to its inital concentration (but relative to the previous experiment it has still increased).

Anyone agree (if it was hydrogen that had its concentration increased, my answer is the same but swap hydrogen and Iodine around)?

I think I got 0.0448
I have no idea where the range will be, because I've seen all sorts of answers from 0.02-0.05

ah OK, do you reckon if we used delta G but did the right method we would still get 0/2 yeah?
99/100 is still pretty damn godly

Does anyone remember the figures for the CO2 question?

Probably 0/2, sorry (assuming it is wrong). And I doubt I got 99/100 - probably made other errors, particularly in written questions (that Cl2/ClO question was a bit odd).

Ah ok cool. I got NiSO4.7H2O at the end but didnt use the method that everyone else, as in i missed 1 step, i reckon i could lose 2 marks for that!

Are you sure we definately had to times it by 6 for the CO2 question.

The enthalpy change of reaction definition suggests not

3.4x10^18 kJ I think. Enthalpy was 2879 I think and entropy about -256 (J, not kJ).

what did people get for the order? i got first order because the half life was constant?