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AQA Chemistry New AS Unofficial Mark Scheme

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Reply 40
Original post by haes
because you take the values that are concordant only


This. Values should be within 0.1
Reply 41
Original post by DaVinciGirl
That's also true, but I took it as you know what mass you need to make the solution. It was a six marker, so if that didn't need to be included, I'm not sure what the other marks were needed to be.


well i truly hope that the mark scheme will be kind in that question... there was a similar practical procedure question about distillation in the 2nd specimen paper and if i recall correctly the mark scheme wasn't really specific about marking points :/
Original post by haes
Isn't the MPC question about the sulfuric acid D? because i remember it was between KOH and Ba(OH)2?
if H2SO4 reacted with KOH it would form K2SO4 and H2O, and that would need to be balanced to 2KOH.
but when H2SO4 reacted with Ba(OH)2 there was no need to balance and the moles of the barium hydroxide was 0.05 as well?

Oh I believe you're right. I forgot which one I put down for that one, either it was D or A. Thanks!
Reply 43
Original post by DaVinciGirl
Do we not use solutions during chemistry for other practicals?


I was trying to apply it to the experiment itself. But who knows... up to AQA to decide the points for the six marker
Original post by Gswp
no, only two values


Oh **** how many marks will lose? Got 149 for the second part though :frown:
Original post by Gswp
This. Values should be within 0.1

Oh I wasn't taught that reason. I'll add that into my notes a bit later. Thank you.
Reply 46
Original post by rosemondtan
Oh **** how many marks will lose? Got 149 for the second part though :frown:


to be honest i nearly did the same mistake lol. But i think you'd lose maybe 1 mark, 2 max. AQA did it on purpose to trick students so a they'll award a mark at least as many people will have done the same i assume
Reply 47
Original post by DaVinciGirl
Oh I wasn't taught that reason. I'll add that into my notes a bit later. Thank you.


yeah... i only came across it during the required practical when my teacher told us to ignore values not within 0.1cm^3
Original post by Gswp
yeah... i only came across it during the required practical when my teacher told us to ignore values not within 0.1cm^3

Quite annoying, but all well. Now all my friends lost marks on that question :redface:
Reply 49
If we used all 4 values from the table when calculating the titre mean, is everything wrong? including the next question about Mr?
Reply 50
for pv=nrt what was the appropriate number of significant figures? all the values given were in 3 s.f. but temperature was 300K and i wasn't sure if that was 3sf or 1, so i put my final answer as 1sf..
Reply 51
Original post by hbaig27
If we used all 4 values from the table when calculating the titre mean, is everything wrong? including the next question about Mr?


i'm sure you'd get error carried forward? what did you get as your answer for Mr?
Reply 52
Original post by DaVinciGirl
Quite annoying, but all well. Now all my friends lost marks on that question :redface:


Have to thank you for this mark scheme though - much appreciated :smile:
Reply 53
Original post by haes
i'm sure you'd get error carried forward? what did you get as your answer for Mr?


I got 57, which i know is wrong because the answer is 147 or something. My moles calculated was 9.9x10^-3
Reply 54
Original post by Gswp
to be honest i nearly did the same mistake lol. But i think you'd lose maybe 1 mark, 2 max. AQA did it on purpose to trick students so a they'll award a mark at least as many people will have done the same i assume


lol I thought the trick was the 'rough titre' but AQA aren't that stupid.
Original post by Nechromatic
I'm sorry but the first question is wrong its actually: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d1.

No it isn't even though the 4s shell fill before 3d, 4s is the outer shell so electrons are lost from it
Reply 56
Did the ionisation energy question say it needed state symbols?
Reply 57
What did you guys get for the percentage question before the multiple choice question?
I got like 26/29%
Reply 58
Original post by hbaig27
Did the ionisation energy question say it needed state symbols?


No but they expect you to add them
Original post by A.aaa
What did you guys get for the percentage question before the multiple choice question?
I got like 26/29%


I personally got 35.5%

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