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AQA Chemistry C3 - Unofficial Mark Scheme

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Original post by LilyKitty
There wasn't one so dw, think some people are doing the other spec. 😊 Xx


But didnt u just say that u got the same answer as me for the bond question, 212, so how are we doing different specs?
Original post by mediaya
But didnt u just say that u got the same answer as me for the bond question, 212, so how are we doing different specs?



Oh dear, I don't know, yes I did get 212. Really sorry I am very confused now cos I definitely didn't see a specific heat capacity calculation on the paper. Sorry. xx
Original post by LilyKitty
There wasn't one so dw, think some people are doing the other spec. 😊 Xx


I was thinking that was weird, I got +212 for the bond energy one too, others must have had a different exam
Does anyone know if the OP is going to update this unofficial mark scheme? I appreciate the original effort but it is very disorganised; there is a lot of uncertainty amognst people as different exams have different answers etc.
(edited 7 years ago)
Original post by LilyKitty
Oh dear, I don't know, yes I did get 212. Really sorry I am very confused now cos I definitely didn't see a specific heat capacity calculation on the paper. Sorry. xx

But i never said there was specific heat capacity question 😕 you probably misread my post 😅 (seeing that there was sooo many people talking about the SHC, u thought i was saying there was too but no!)
To clarify, there was no specific heat capacity calculation on OUR spec
Original post by mediaya
But i never said there was specific heat capacity question 😕 you probably misread my post 😅 (seeing that there was sooo many people talking about the SHC, u thought i was saying there was too but no!)
To clarify, there was no specific heat capacity calculation on OUR spec



Okay haha, really sorry again for confusion, it has been a long day 😔haha. Are you doing further additional physics on friday. How are u feeling for it? xx
Original post by LilyKitty
Okay haha, really sorry again for confusion, it has been a long day 😔haha. Are you doing further additional physics on friday. How are u feeling for it? xx


Yep doing physics on friday 😑 and i really hate it 😣. I like biology and chemistry but physics and its stuff about maganets and all that i hate it 😧. What about u?? Hiw u feeling about it? And btw am meant to be revising right now for physics but see what i am doing..... Again procrastinating.....
Original post by RayRay99
Last question:

Low temp is needed for a higher yield of ammonia as the forward reaction is exothermic.
But this would decrease the rate of reaction too much so a comprise temp of 450'c is used.

A high pressure would also give a higher yield as there are fewer molecules in the right than on the left.
But a higher pressure costs too much money so a compromise pressure is used. (200atm)

I said about high pressure increases yield but i didnt talk about molecules???? I was going to but then forgot
Can someone help me please?!?!?

The question that asked to draw the energy level diagram was 4 marks.

I drew the diagram but used straight lines. Would I get the marks?

I drew a line upwards from the reactants then I drew a horizontal line then a line downwards and then a horizontal line (below the reactants) to show the products. I labelled the activation energy as an arrow from the level of the reactants to the highest horizontal line and the overall energy change was an arrow from the level of the reactants to the level of the products which is below the reactants. Because I used a ruler to draw straight lines I'm worried I may lose marks?

Here is a picture of what I drew:
4704b.png
Btw the line from reactants to top line is shorter than the line from the top to products because it was an exothermic reaction in the exam. In the image attached it shows the opposite (an endothermic reaction).
(edited 7 years ago)
Original post by theone97
3444


I put 3444 as the answer but because i was not sure i put a line of working under my first answer and did 0.8 x 4.2 x temp change which was 55 J. Would i lose marks? I had 2 answers shown in my working but put 3444 in the answer box
Original post by Mahrez
i got -486.5


i got it as i did the further additional science not triple chemistry
Original post by guy321
Can someone help me please?!?!?

The question that asked to draw the energy level diagram was 4 marks.

I drew the diagram but used straight lines. Would I get the marks?

I drew a line upwards from the reactants then I drew a horizontal line then a line downwards and then a horizontal line (below the reactants) to show the products. I labelled the activation energy as an arrow from the level of the reactants to the highest horizontal line and the overall energy change was an arrow from the level of the reactants to the level of the products which is below the reactants. Because I used a ruler to draw straight lines I'm worried I may lose marks?

Here is a picture of what I drew:
4704b.png
Btw the line from reactants to top line is shorter than the line from the top to products because it was an exothermic reaction in the exam. In the image attached it shows the opposite (an endothermic reaction).

LOL I did the same thing I'm afraid I don't how much marks we would get (C3 was sooo hard what do u think grade boundaries will be) someone post the answers to the questions on the periodic table
(edited 7 years ago)
Original post by LilyKitty
Yes that is what I got too!!! Was really starting to panic cos loads of people were saying exothermic but me and my friends all said read it as endothermic and got 212. xx And think I did get that for the balancing equation. Is there a full unofficial markscheme for our spec yet??? xx

This is the link to the further additional science C3 specs
http://www.thestudentroom.co.uk/showthread.php?t=4167269
Reply 453
Original post by user2k16
the bond energy question I didn't get a minus (-) as it was an endothermic reaction ?


It told you on the next page that it was an exothermic reaction.
Could anyone please tell me what this would get overall?

ISA: 48/50
C1: 56
C2: 54
C3: 40

Thanks.


Posted from TSR Mobile
Reply 455
Original post by mrtum3000
Corrections:
''Tube B: calcium carbonate produced, solution goes cloudy'' - carbon dioxide makes limewater go cloudy
''How is methane obtained: Cows (?)'' - natural gas
''Element that has low boiling point: F'' - Rb is also valid I think


@ the people saying it is Rb, this is wrong
the boiling point of rubidium is 687.8 °C
the boiling point of fluorine is -188.1 °C
Reply 456
Original post by dausa99
Could anyone please tell me what this would get overall?

ISA: 48/50
C1: 56
C2: 54
C3: 40

Thanks.


Posted from TSR Mobile


I'm pretty sure this would be an a*
Your ISA and C1 score will probably be 100UMS and if you're lucky so will your C2 UMS which will easily pull up your 40 in C3
Original post by Account user
TBH I'm actually being realistic with my C3 mark😐 So let's say I got these marks (after recounting) C1:45 C2:48 and C3:28 it should be an A? Along with the same ISA grade thanks much appreciated!!


ISA borderline A/A*
C1 A
C2 again borderline A/A* but thinking about it, the boundaries will probably be quite high for this paper esp considering the 6marker so most likely on the A side
C3 C

i think overall that'd hopefully be a good A :crossedf::crossedf::crossedf:
Reply 458
Original post by guy321
Can someone help me please?!?!?

The question that asked to draw the energy level diagram was 4 marks.

I drew the diagram but used straight lines. Would I get the marks?

I drew a line upwards from the reactants then I drew a horizontal line then a line downwards and then a horizontal line (below the reactants) to show the products. I labelled the activation energy as an arrow from the level of the reactants to the highest horizontal line and the overall energy change was an arrow from the level of the reactants to the level of the products which is below the reactants. Because I used a ruler to draw straight lines I'm worried I may lose marks?

Here is a picture of what I drew:
4704b.png
Btw the line from reactants to top line is shorter than the line from the top to products because it was an exothermic reaction in the exam. In the image attached it shows the opposite (an endothermic reaction).


This made me panic so much I thought I'd confused endo and exothermic graphs and put the wrong one!

But yes - this will still be credited the maximum number of marks you could lose is 1 but its still unlikely.

At least you didn't forget to label overall energy change as I did..
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.


I thought that but the boiling point of Rb is 687.8 °C and fluorine is -188.1 °C

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