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AQA AS Chemistry 7404/1 and 7404/2 - 27th May 2016 and 10th June 2016

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Original post by rheajain
I literally just put that temporary dipoles are set up between the molecules lol. Yeah I think I did! yes silicon does have the highest melting point. Yeah, I think I put sulphur as the biggest jump was between 6 and 7. I don't remember what I put I think I got 1.2 something as the mass? Yeah that was piss easy tho I was like wow. They didn't even give a graph


Yeah I thought that exam was pretty good, compared to last year, what grade are you hoping to get in it?
(edited 7 years ago)
Has an unofficial mark scheme been made?
Original post by aimeekaur
Has an unofficial mark scheme been made?



http://www.thestudentroom.co.uk/showthread.php?t=4125207
Is their a mark scheme for the chem unit 1 Resit?


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Original post by Chocofudge123
Is their a mark scheme for the chem unit 1 Resit?


Posted from TSR Mobile


http://www.thestudentroom.co.uk/showthread.php?t=4124307&p=65233395#post65233395

Here's one
is there a paper 2 thread?
Original post by ramseyisbuff
is there a paper 2 thread?


This is is g
Original post by rheajain
I literally just put that temporary dipoles are set up between the molecules lol. Yeah I think I did! yes silicon does have the highest melting point. Yeah, I think I put sulphur as the biggest jump was between 6 and 7. I don't remember what I put I think I got 1.2 something as the mass? Yeah that was piss easy tho I was like wow. They didn't even give a graph


Lucky old spec people. Really really lucky :tongue:
How did everyone find the paper 1 AS Chemistry ?
Original post by OfficialChemist
This is is g


then why are people still talking bout the first one g?
Original post by ramseyisbuff
then why are people still talking bout the first one g?


Because it was a hard paper, can't blame em tbh
http://www.thestudentroom.co.uk/showthread.php?t=4074387
Aside from these 2 specimen papers from AQA, are there any other papers for Physical+Organic that I can do?
What's everyone's predictions for Chem unit 2 resit? Do you think it's going to be hard?


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Original post by Chocofudge123
What's everyone's predictions for Chem unit 2 resit? Do you think it's going to be hard?


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Are there any predictions for paper 2 floating around ? Its impossible to get an idea looking at the past papers.
Can someone list the topics in paper 2?
Hey

For this part of the spec for paper 2:

explain how the method used to oxidise a primaryalcohol determines whether an aldehyde or carboxylicacid is obtained

How would you explain it? Would you say reflux for carboxylic acids and distillation for aldehydes but do you need to know why you do reflux/distillation respectively?
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oxe
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Hi,
Does anybody have Set 2 Mark Scheme (only need the MS) ples. I only Physics Set 2 MS and Paper if anybody needs it (i know this is chem but...)
Thanks.
Original post by metrize
Can someone list the topics in paper 2?


I've attached a list of what topics are included in paper 2

Hope this helps x
Chem Paper 2 list.docx14.7KB
It says explain... so maybe a sufficient amount of detailed is required. Quite hard to tell without an indication of how many marks it would be.

And yes I think you're just about correct with reflux with carboxylic acid and distillation with aldehydes.
And yes again - you may have to explain them respectively;

So the reason why you want to DISTIL aldehydes is because it can be easily oxidised to carboxylic acid if it is in excess. Using a condenser as a make-do distillation column allows the aldehyde produced to condense into a liquid and be collected - in a sense it allows equilibrium to shift to the right since continuously removing the product prevents any of the produced aldehyde to quickly oxidise into carboxylic acid. This is a PARTIAL oxidation of alcohols.

Reflux however is basically allowing the product to condense and drop back down in solution. So excess aldehyde is still present for full oxidation. It's quite a different set-up to a distillation set-up. (Condenser is at the top to allow the condenses liquid to drop down back into flask).
So anyways, heating the alcohol solution under REFLUX allows FULL OXIDATION to the carboxylic acid.

And you might need to know your Test for Functional Groups as well - just for the safe measure.
The test for aldehydes can either be using Tollen's re-agent / Benedict's / Fehling's
The test for carboxylic acids is basically adding Sodium Hydrogden Carbonate (look it up - i'm not too sure) which will fizz to produce Carbon Dioxide, and if you bubble it through limewater it should turn cloudy.

So if you oxidise the alcohol using an oxidising agent (e.g potassium (IV) dichromate) and it tests positive for aldehydes - then it's an aldehyde.
Oxidise an alcohol under reflux using the same oxidising agent, and it tests positive for carboxylic acids - then it's a Carboxylic acid.

Hope this helps :smile:
I predict that, as well as all the Organic topics and Kinetics, this paper 2 will have energetics and equilibria on it as they were barely touched in paper 1 even though they're across both papers. Although they still could be evil and throw it in, Bonding was heavily on paper 1 so I don't think there'll be many bonding q's (probably a few multiple choices I reckon). Amount of substance is bound to reappear - i think we'll get some general moles stuff (the easy triangle formulae) considering paper 1 had amount of substance q's involving the horrible titrations and that ridiculous physics question!!!!!

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