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Aqa chem 4/ chem 5 june 2016 thread

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Very easy paper! Definitely a bit harder than last years though so I would guess grade boundaries will be similar or perhaps 1/2 marks lower

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Reply 2301

zombaldia

Original post by Fibsy

I found it mostly easy but I don't want to get my hopes up. The questions i didn't get were:
What is the effect on emf of increasing pressure of oxygen?
Ditto for effect of increasing Pt surface area
Conditions under which E for something was something (I put in circuit with standard hydrogen electrode with 298K etc)

For the titration calculation I out something like 96%? Sneaky of them to make the compound have three C2O4 ions in

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If you look at the equation it's just le chatelliers so inc pressure means more h2o produces which means more redox and less oxidation and so emf inc.

Sa has no effect

conditions are 298k, 100kpa(although not sure if relevant there) and then 1m solution

Reply 2302

lahigueraxxx

Anyone else get something like +1910 for the Born Haber cycle?

Reply 2303

Cadherin

Original post by zombaldia

Solid is cr(h2o)3(oh)3 and the gas is co2, it's M3+ with co32- reaction

Yeah, *******s, I should've picked up on that.

Reply 2304

Johnny98

Enthalpy for lattice dissociation was 2328? And did we have to work out enthalpy of solution, this was negative answer wasn't it?

Reply 2305

zombaldia

Original post by greenmath

Wanted a nice exam paper but I thought that was a bit too nice, grade boundaries are going to be sky high

Yeah I agree. wasted a day of revision. I'm ****ed for c4

Reply 2306

openmyeys

Original post by perpetua

If there is a lot of crossing out but the answer was correct.... Is it ok

If you look at previous mark schemes they want full working out for the marks, as long as you showed them how you got your answer you will be fine, but you will always get a mark for a correct final answer

Reply 2307

chloeabeki

Original post by Sufyxyz

It was 2238

wasnt it 2328?

Reply 2308

Cadherin

Original post by cowie

Very easy paper! Definitely a bit harder than last years though so I would guess grade boundaries will be similar or perhaps 1/2 marks lower

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I think they'll be higher than last year to be honest, I'm expecting 95/100 for 120 UMS, 87/100 for A*, etc.

Reply 2309

cowie

Original post by zombaldia

I thought hydrogen oxygen cell was my reversible and hence lie chateliers principle wouldn't have any effect?

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Reply 2310

Cadherin

Original post by chloeabeki

wasnt it 2328?

It was something like that, but I remember all those numbers appearing!!

Reply 2311

Johnny98

Anyone remember for lattice dissociation. Did we get given atomisation of oxygen or bond enthalpy of oxygen?

Reply 2312

Charco63

Original post by cowie

Very easy paper! Definitely a bit harder than last years though so I would guess grade boundaries will be similar or perhaps 1/2 marks loweRe

Agree 100%

Reply 2313

12284

what were the reagents used to change Cr3+ to Cr2+?
i wrote Zn with H+?

Reply 2314

calh97

I didn't multiply my moles of c2042- by 3 as I didn't see they was 3 of them in the formula, will I get about 5/6 marks for the question??

Reply 2315

Studious_Student

I completely blanked on the purity question. How many marks would I get if I get the 2 half equations right, but the overall equation is wrong? And I did all the method right but got the wrong answer? Overall I feel like this paper was good, but made a lot of stupid mistakes.