The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Aqa chem 4/ chem 5 june 2016 thread

Scroll to see replies

Original post by 12284
Isn't the positive and negative electrodes the wrong way around?


The example I gave may be the wrong way around yup!
Original post by DDan123
I think after chem 4 a lot of people have just found this paper a lot easier in comparison. But I agree. It wasn't an extremely easy paper, but not insanely difficult.


Posted from TSR Mobile


Yeah I didn't resit chem 4 this year so I don't have that to compare to, and it's a bit inaccurate to compare chem 5 to chem 4 grade boundaries because they're completely different papers.
Original post by ravichauhan11
everyone remember to include that deltaH was approx 0 because same amount and type of bonds being broken and formed? for the thermo stability Q


what thermo stability question?
For increase O2 pressure I put decrease EMF?

because Ecell=Ered-Eox

Reduction EQM would shift to left to oppose change, decreasing Ered, therefore decreasing Ecell?
Original post by 12284
Ohh that makes sense...
do you remember how many marks that was?


1 mark for each half equation
1 mark for overall equation
= 3

Original post by no-1
Probably my worst error on the paper. That was what, 3 marks?


Yup.
Original post by no-1
Probably my worst error on the paper. That was what, 3 marks?


Yep. I'm pretty sure the rest of it was fairly good unless I slipped up somewhere and haven't realised.
Original post by Kay Fearn
Damn lost two marks on the alkaline fuel cell question, couldn't work it out in time.

Also got 35.2% for the % purity question but that's % by mass so think i lost like 4 marks from both of those^^

i said increase in pressure increases emf because when more oh- formed/reaction speeds up not sure if that's right tho :/

For the last 3 marks what did people say? I talked about mixing two solutions indifferent proportions one containing ligand and one containing mn04- then shine light through a filter at the solution and use data logger to measure absorbance then find ratio at max absorbance.


- Answer about pressure is correct because it does increase emf
- Answer about colorimetry is wrong because how does MnO4- bond with ligands??? It is not a transition metal, plus it's already a purple solution. Finally, data logger????? It's a colorimeter.

Well done for the pressure one, I'm sorry but I think you may only get 1 mark max for your answer about the colorimeter
I got 50.7 for purity too
(edited 7 years ago)
Original post by K2Cr2O7
Formation of complex ions
Coloured ions
Variable oxidation states


No 'catalytic properties'? :frown:
Original post by Maki.98
It asked about the enthalpy change so I dont think you do it to one mole. I know the question you're talking about but that one had to specifically say 1 mole


if you're working out enthalpy or entropy though then the units are per mole, so i divided by 2. Idk though i was unsure which to do.
Did anyone out KNO3 for the acid on question?8??? I literally was thinking it could be any so just went with that but now I'm writing this I realise it could've formed KMno4- so


Posted from TSR Mobile
Original post by no-1
No 'catalytic properties'? :frown:


I said that because it said cobalt and ITS COMPOUNDS :smile:
Original post by hi-zen-berg
For increase O2 pressure I put decrease EMF?

because Ecell=Ered-Eox

Reduction EQM would shift to left to oppose change, decreasing Ered, therefore decreasing Ecell?


i put this as well
Original post by minjinoor
what do you think grade boundaries will be?????


I genuinely don't know. I find chem5 easier than chem4. If I was estimating:

67/68 - B
76/78 - A
83/85 - A*
Original post by no-1
No 'catalytic properties'? :frown:


Yes thats the 4th one.
Reply 2555
Avatar for tbh12
tbh12
9
Original post by no-1
No 'catalytic properties'? :frown:


Yes, catalytic properties would also be on the mark scheme.
Original post by hi-zen-berg
For increase O2 pressure I put decrease EMF?

because Ecell=Ered-Eox

Reduction EQM would shift to left to oppose change, decreasing Ered, therefore decreasing Ecell?


I wrote this too, but everybody saying it was increased :frown:


Posted from TSR Mobile
Original post by hollyclaireee
Did you write the units of deltaG as Jmol-1? If you did then you should get all the marks I think!

Then if you did deltaS divided by 1000 instead you'd have to give units of deltaG to be kJmol-1 right?


I think I wrote my units as JK-1mol-1 because that's what delta s was given in? Can't really remember though.
Original post by randoms132
[Cr(h20)3(oh)3](s)


Posted from TSR Mobile


So X(g) = CO2 ?
How many marks do you lose for not converting degrees to k?

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you