Edexcel A2 Chemistry 6ch04/05 JUNE 2015

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What do we have to know for this specification point???

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For infra-red you will have to be able to use the Data Booklet and/or graphs they provide and quote the correct values for the peaks and analyze it to figure out compounds. They may also not give a graph and simply provide you with values, and you will have to find what type of bond stretching the values correspond to from the Data Booklet.

According to my notes, you have to be able to describe simply how microwaves heat up things and know that it affects all POLAR molecules but not non-polar molecules.

UV ray causes homolytic fission and free radical substituition. This is covered in earlier units regarding ozone depletion and alkane reactions.
That's the important part. My notes also mention that UV is used in the technique of flash photolysis. They've said that it used by: 'subjecting a sample to intense UV radiation which excites the system and making observations when the system relaxes'. But there's no details given other than this sentence, so this method is not necessarily required. We simply have to know that it can be used in the analysis of molecules/particles. Edit: I've also NEVER seen this any of the past papers, haha.

Radio waves are used in NMR spectroscopy. You have to understand the basic theory of how it affects the spin of a proton, because this is the principle that NMR relies on as H atoms in different environments will resonate at different frequencies allowing identification.

You may be asked why TMS (tetramethylsilane) is used as a reference compound in nmr, but you will not be required to know any further details on this compound.

You will be required to know how to analyze both low resolution and high resolution NMR peaks and identify structures using the information given. They may also ask for uses of NMR for a couple of marks. :smile:

That's all I can think of.

(edited 8 years ago)

Reply 781

Wahid1

Yo someone pls help me before i have breakdown pls

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Reply 782

HaydenMoussa

can someone list the key points of how buffer solutions work, just so I know where the marks are. An example with ethanoic acid and sodium ethanoate?

Reply 783

bbyturtlexox

lattice enthalpies in data book. you always use the ones NOT in bracket right?

Reply 784

Gg7

Okay so here's the thing
I get pretty much everything on acid base equilibria except titration curves
can someone for the love of god go through the steps of plotting a titration curve
and where exactly marks would be awarded
Thanks in advance :smile:

Reply 785

Hairysweets

Look at 11 (d)! Edexcel made a typo, I want to see grade boundaries dropped now or else!:

http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/Mark-scheme-Unit-4-(6CH04)-Paper-1R-June-2014.pdf

Reply 786

Maham88

Original post by Gg7

here have look at the last few pages https://chemrevise.files.wordpress.com/2014/04/4-acid-base-equilibria.pdf

Reply 787

Wahid1

Please answer me someone :frown:

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Reply 788

Maham88

Original post by Wahid1

Please answer me someone :frown:

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what is your question ?

Reply 789

Wannabe007

Original post by Wahid1

Confirmation required

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I havent seen anything more than MCQs and those 6 mark Qs. That knowledge should suffice.

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Reply 790

Wahid1

Original post by Maham88

what is your question ?

2 questions on the previous page :smile:

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Reply 791

Wahid1

Original post by Wannabe007

I havent seen anything more than MCQs and those 6 mark Qs. That knowledge should suffice.

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Thanks!!

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Reply 792

thymolphthalein

Original post by lizzie97

Can someone please do this question and go through it step by step, preferably taking a photo of your method please? im so confused
An experiment was carried out to determine the value of Kc for this reaction.
0.120 mol of ethanoic acid was added to 0.220 mol of ethanol.
5.00 cm3 of 1.00 mol dm–3 hydrochloric acid was added as a catalyst. Thiscontains 0.278 mol of water.
The mixture was left to reach equilibrium.
The mixture was titrated with 1.00 mol dm–3 sodium hydroxide, whichreacted with both of the acids.
The titre was 45.0 cm3. Use these data to determine the value for Kc.

Reply 793

Wahid1

Original post by thymolphthalein

Or you could simply do the usual by subtracting the HCl titre from that of the equilibrium mixture to give you the real volume

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Reply 794

Maham88

Original post by Wahid1

2 questions on the previous page :smile:

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the chemguide one or ...?

Reply 795

simsid

i know hardly anything about the hydration stuff that we need to know? does anyone have any tips to learn this as it was in the section C of june 2012 and i found it very hard

Reply 796

Hairysweets

Original post by bbyturtlexox

lattice enthalpies in data book. you always use the ones NOT in bracket right?

If you read above the values it tells which are the actual values and which are the (theoretical values). Use the actual values!

Reply 797

thymolphthalein

Original post by Wahid1

Or you could simply do the usual by subtracting the HCl titre from that of the equilibrium mixture to give you the real volume

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Uhh...that IS how I got 0.04 mol.

But most people ask how or why that is equal to the amount of CH3COOH remaining, I was trying to explain that part.