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AQA Chemistry C3 - Unofficial Mark Scheme

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Reply 40
Original post by arj2104
How many marks was the Specific Heat Capacity question


I think 3
what was the methane q
what did everyone write for question 1 with test tube 1 and 2?
what about the catalyst used for esters?
The lowest boiling point was Rb
Original post by Roquebrune2014
For bond energies I am 100% sure it should be (-)1,276. I wrote out all the bonds underneath next to their bond energies, added up each side of the reaction and checked the numbers 3 times (I finished quite early so thought I'd count up each side again)


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Yep, I just told someone that not putting a minus won't lose you a mark but they had what I think was the wrong answer... I agree from what I remember that it's -1,276kJ/mol
Original post by YAY GCSE
It was definitely an exothermic reaction which gave a negative enthalpy change and I'm 100%on this because at the start of the next question is said "this reaction is exothermic" lol


I thought it said "this reaction is exothermic" on the following page. I remember because I was unsure if I had done the calc right (ending up with negative value) and the statement basically confirmed I got the question correct/on the right lines at least :smile:
Reply 46
For the energy change I divided 3444 by 0.8 and go 4305? ANYONE ELSE?
Original post by Scarliemarie
The lowest boiling point was Rb


Nope, it was fluorine - check google if you don't believe me - it's well known google never lies. :-)
Original post by bod247
Its Rb because in group 1 (alkali metals), the Boiling point and Melting Point decrease as you go down. Rb was the last Alkali Metal so its the lowest Boiling Melting/Point.


Yes but rubidium is a solid at room temperature and fluorine is a gas, so it should be fluorine.
Original post by Aminah53
What did everyone get on that table question which asks about the changes of the solutions?
I got white precipitate for the calcium one, no change for both the water one, no change for one of potassium and for the other potassium one I wrote fizzing and bubbling which i think is probably wrong.


I got no change for all except 1 of them where I said white precipitate! It looked really wrong lol but oh well.
Original post by Sadxa
For the energy change I divided 3444 by 0.8 and go 4305? ANYONE ELSE?


The question only asked for energy released by 0.8g of the fuel but you worked it out for 1g of fuel. There was no need to do that
Original post by etata
I got that too


That answer is right
Reply 52
What was the first question and the methane question?
Reply 53
Original post by Sadxa
For the energy change I divided 3444 by 0.8 and go 4305? ANYONE ELSE?


Yup...RIP
Anyone else get -217 for bond calculation?
Reply 55
Original post by miamathewss
what did everyone write for question 1 with test tube 1 and 2?
what about the catalyst used for esters?


I assume u mean the first question? Tube 2 limewater went cloudy, and I guessed tube one saw bubbling as carbon dioxide was produced?
Reply 56
Original post by chelseafc141
I got -1276 for the bond energies


me too
Original post by Youngey4
Yes but rubidium is a solid at room temperature and fluorine is a gas, so it should be fluorine.


The answer is rubidium
I put animals like cows/cattle as they produce alot of methane. Friends put natural gas and biogas too
Reply 59
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
it was 50j 0.6* specific heat capacity * temp change

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