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8CH02 Paper 2 EDEXCEL CHEMISTRY Friday 10th June 2016

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Original post by P_Digby
Was is H2S04 and K2Cr2O7 and then heating under reflux?


I wrote that then crossed it off. The examiner better give it to me (probably not) 😂😭😭😭😭


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I thought it was fairly nice. Nothing was particularly hard, the n value was the only one that required some thinking - got 2.26 to 3 sf in the end.
Reply 22
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P_Digby
2
Original post by Florent venhari
I wrote that then crossed it off. The examiner better give it to me (probably not) 😂😭😭😭😭


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Yeah I think "The examiner better give it to me (probably not)" really just sums it up aha.
Grade boundary predictions:

A - 59
B - 53
C - 46
D - 39
E - 35
F - 31
U - x < 31




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Reply 24
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P_Digby
2
Original post by Florent venhari
Grade boundary predictions:

A - 59
B - 53
C - 46
D - 39
E - 35
F - 31
U - x < 31




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On balance that seems fair, although the new specs always do seem to have a lower grade boundary, so there may be hope yet!
Original post by Astro_Joe
I got n=2.25 so I rounded it down to 2 as it had to be a whole number. I'm not sure if it's right, but the fact that it's not a whole number is explained by the question after, so maybe it is.


what did u get for the question after? i said it would decrease the titre and decrease the value of N
Original post by P_Digby
Was is H2S04 and K2Cr2O7 and then heating under reflux?


no it was dehydration so it was just conc suluric acid and then reflux it think
Original post by clairebear101
what did u get for the question after? i said it would decrease the titre and decrease the value of N


It would decrease the titre but increase the value of n, because more of the original mass of the acid-water complex would be attributable to the mass of the water.
(edited 7 years ago)
Original post by Astro_Joe
It would decrease the titre but increase the value of n, because more of the original mass of the acid-water complex would be attributable to the mass of the water.


i just guessed as i coudlnt work out the value of N, will i get 1/2 marks then? for saying that teh titre would be less as the acid is more diluted due to it being moist
Original post by clairebear101
i just guessed as i coudlnt work out the value of N, will i get 1/2 marks then? for saying that teh titre would be less as the acid is more diluted due to it being moist


Yeah I'd imagine you'll still get half the marks for that question.

At least you didn't do what I did and forgot that by 'conditions' they actually meant stuff like 'reflux' and 'heat' rather than just 'acidified.' That was a stupid idea.
I said that the value of n would increase as there is more water being added than expected, so the coefficient would be higher


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Ozil5
8
Is anyone else not getting into university now
Original post by Astro_Joe
Yeah I'd imagine you'll still get half the marks for that question.

At least you didn't do what I did and forgot that by 'conditions' they actually meant stuff like 'reflux' and 'heat' rather than just 'acidified.' That was a stupid idea.


I swear it was a dehydrationa nd so it was just conc phosphoric acid and reflux it
What would 100 UMS be?
Original post by SolomonP
What would 100 UMS be?


76 probably


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Original post by clairebear101
I swear it was a dehydrationa nd so it was just conc phosphoric acid and reflux it


I may be remembering wrong, but if the product was an aldehyde, a carboxylic acid or a ketone, then the answer was definitely acidified potassium dichromate and heat with reflux/distillation.
Reply 36
Avatar for zak_121
zak_121
2
Unofficial Mark Scheme?
Which way were the arrows supposed to be drawn??? I got + 70 something for the enthalpy change (the 2 mark one). I got -23.50 Kj mol -1 for the part before it????


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Original post by Astro_Joe
I may be remembering wrong, but if the product was an aldehyde, a carboxylic acid or a ketone, then the answer was definitely acidified potassium dichromate and heat with reflux/distillation.


i swear it was a dehydrated Di-ol
Original post by clairebear101
i swear it was a dehydrated Di-ol


dw, ithink i read it wrong :frown: exam panic :frown: if it was 2 marks will i still get a mark for heat under reflux?

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