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AQA Chemistry C3 - Unofficial Mark Scheme

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Original post by Himani Vadhia
thats what i got!!!!!!!

You went wrong with the 0.8 bit. That was the mass of fuel burnt when you are ment to use 50 which was the mass of the water.
Original post by Lmemon123
For the titration question , i said to put the alkali in the burette and acid in the flask does it make a difference?


Same and everyone is telling me it's wrong but I don't see why :s-smilie:
Original post by surina16
Same and everyone is telling me it's wrong but I don't see why :s-smilie:


It shouldn't matter, the method is still the same.
Yeah for everyone wondering, the 0.8g wasn't meant to be used at all.
AQA included it as a sort of 'trick' to see if you knew what mass you were actually meant to use instead of plugging all of the values into the equation :smile:
If you did use 0.8g though, you should still get 1 mark from what I have seen in past papers :h:
Original post by YAY GCSE
You went wrong with the 0.8 bit. That was the mass of fuel burnt when you are ment to use 50 which was the mass of the water.


oh
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Zhundo
1
Original post by surina16
Yeah for everyone wondering, the 0.8g wasn't meant to be used at all.
AQA included it as a sort of 'trick' to see if you knew what mass you were actually meant to use instead of plugging all of the values into the equation :smile:
If you did use 0.8g though, you should still get 1 mark from what I have seen in past papers :h:


Yep, the 0.8g is also included so you can calculate the mass per 1g burned which is on most past papers, but they didn't include that in this paper for some reason.
Original post by Zhundo
Yep, the 0.8g is also included so you can calculate the mass per 1g burned which is on most past papers, but they didn't include that in this paper for some reason.


It's annoying! I was getting ready to calculate kJ/g, kJ/mol etc because the maths bits in chem are the best :lol:
Original post by Zhundo
Yep, the 0.8g is also included so you can calculate the mass per 1g burned which is on most past papers, but they didn't include that in this paper for some reason.


That's probably what threw me off, normally you would convert it to 1g and if you had done it wrong you would realise.
Original post by harry9s
It shouldn't matter, the method is still the same.


peak, this makes me feel better :biggrin:

Spoiler

The answer with the lowest boiling point was F, because think about it, fluorine is a gas a room temperature and rubidium is not, therefore F has the lowest boiling point
Original post by milolj
Will you lose a mark for saying 1623 rather than -1623?


That wasn't the answer, but on past papers they tend to ignore any signs given anyway so wouldn't worry
Original post by TheAnon121
For specific heat capacity, I got 3444J. And some people said it was F for that and some Rb - not sure which one was right


F has the lowest boiling point because it's a gas at room temp
Reply 392
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123Kady
The bond energies question had to have an answer of positive integers given that the following question stated that the reaction was endothermic
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Zhundo
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Original post by 123Kady
The bond energies question had to have an answer of positive integers given that the following question stated that the reaction was endothermic


The following question stated that it was exothermic. Plus, the reaction was a combustion reaction so it has to be exothermic.
LOL, why am i the only dumbass that got -2009 fort the bond energy :')
Did everyone find unit 3 harder than Unit 2 or was it just me?
Original post by surina16
oh :s-smilie: Maybe it was something with your calculator...? I stored the values that I got in letters and then minused the letters away from each other :/


@starstudent7 got 2 thousand ish too... 😯
Original post by milolj
Will you lose a mark for saying 1623 rather than -1623?


yeh unfortunately. negative numbers show exoteric reactions, positive numbers show endothermic.
Original post by surina16
Same and everyone is telling me it's wrong but I don't see why :s-smilie:


as long as you explain it right it'll be fine. the indicator was added to the solution in the flask (alkaline = pink, acid = clear) so as long as you said it the right way round it's fine.
What was the answer to the first question where you had to fill in the gaps?

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