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AQA Chemistry Paper 2 AS Level 2016 Unofficial Mark Scheme

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Original post by moshe015
Can u repost the edited mark scheme

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The original post is the edited one. I've been changing it on there.
Reply 81
Avatar for spidle
spidle
12
Original post by Anna1909
For the spectroscopy peak question I think you could also have the C=C bond and the range ☺️ I think


I did that, used the 1620-1680 wave range I think and noticed it was C=C bond.
Original post by haes
How are our overall grades determined? Do they total our marks out of 160?
Also was the honeycomb question 1 or 2 marks?


they make a grade boundary for each i guess and then do a an overall mark
Original post by metrize
Oh well 1 mark, was the last multichoice the argon one


Wouldn't adding argon lead to an increase in V which would lead to a decrease in pressure?(the question was asking us to increase the pressure right or was I an idiot?)
what do you think the grade boundaries will be ?
i found it quite hard
There was a fixed volume

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Reply 86
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uud
1
Original post by Splaffie
i believe you can also talk about zeolites for the separation of octane and isooctane, also wasnt the percentage uncertainty (1/38)*100 since it was + or minus 0.5 which means that the value can deviate by 1?


no the uncertainty of the thermometer is +- 0.25 and they gave us that the uncertainty is +-0.5 for the reading in total because u measure it twice(change) so its 0.5/38.
Original post by uud
no the uncertainty of the thermometer is +- 0.25 and they gave us that the uncertainty is +-0.5 for the reading in total because u measure it twice(change) so its 0.5/38.


+-0.5 means the uncertainty is 0.5 either side of the value, so it can be 38.5 or 37.5 which means its 1, that makes it (1/38)*100
Original post by Splaffie
+-0.5 means the uncertainty is 0.5 either side of the value, so it can be 38.5 or 37.5 which means its 1, that makes it (1/38)*100

In Physics AS Level uncertainty is heavily used in the exams. I always find absolute uncertainty which is 0.25+0.25=0.5. Then you do 0.5/measured value of 38 * 100.
Original post by DaVinciGirl
In Physics AS Level uncertainty is heavily used in the exams. I always find absolute uncertainty which is 0.25+0.25=0.5. Then you do 0.5/measured value of 38 * 100.


nonono it told you the uncertainty was + or - 0.5 because you were measuring it TWICE because remember X +-0.25 - X +-0.25 = +-0.5, you then have to double it to get the absolute uncertainty of 1 because thats the deviation of the value, so (1/38)*100
Reply 90
Avatar for haes
haes
6
Original post by Splaffie
+-0.5 means the uncertainty is 0.5 either side of the value, so it can be 38.5 or 37.5 which means its 1, that makes it (1/38)*100


In the question they stated the uncertainty of the thermometer was 0.25 and because you find two temperatures that makes the total absolute uncertainty 0.5
Original post by haes
In the question they stated the uncertainty of the thermometer was 0.25 and because you find two temperatures that makes the total absolute uncertainty 0.5

I agree :smile:
Original post by haes
In the question they stated the uncertainty of the thermometer was 0.25 and because you find two temperatures that makes the total absolute uncertainty 0.5


you have the two temperatures with an uncertainty of +-0.25, so the uncertainty is +-0.5, so the value deviates by 1
wouldnt the percentage uncertainty be +-1.31% so 2.62%?
Reply 94
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haes
6
Original post by Splaffie
wouldnt the percentage uncertainty be +-1.31% so 2.62%?


the +- sign is there telling you that the true value could be 1.31% lower than your calculated value, or 1.31% higher than the calculated value. I understand what you're saying but the +- is there for that reason
Reply 95
Avatar for SANTR
SANTR
8
Was the volume fixed for the hydrogen question?
I thought the volume decreased?
(edited 7 years ago)
Original post by haes
the +- sign is there telling you that the true value could be 1.31% lower than your calculated value, or 1.31% higher than the calculated value. I understand what you're saying but the +- is there for that reason


i know, but unless you write +-1.31% i think you might actually get it wrong
Original post by Splaffie
i know, but unless you write +-1.31% i think you might actually get it wrong

I don't think so, as percentage uncertainty in the specimen paper wasn't answered like that.
For the temperature difference you read between 2 readings, so 2x0.25=0.5 absolute uncertaintu.

They even told you the uncertainty for the reise of the temoerature was 0.5 why did you go double it again LMAO
Reply 99
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SANTR
8
Original post by metrize
For the temperature difference you read between 2 readings, so 2x0.25=0.5 absolute uncertaintu.

They even told you the uncertainty for the reise of the temoerature was 0.5 why did you go double it again LMAO


Do you know for the hydrogen graph Q, whether the vol decreased?

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