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Chemistry unit 4 AQA

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http://store.aqa.org.uk/qual/gce/pdf/AQA-CHEM4-W-QP-JUN10.PDF

can someone help me with Q4 b how can you tell how many molecular ion peaks there are going to be :/

There are 4 chlorine atoms in that molecule therefore the possible combinations of chlorine atoms will be;
Cl-37 Cl-37 Cl-37 Cl-37
Cl-37 Cl-37 Cl-37 Cl-35
Cl-37 Cl-37 Cl-35 Cl-35
Cl-37 Cl-35 Cl-35 Cl-35
Cl-35 Cl-35 Cl-35 Cl-35
Therefore there will be 5 molecular peaks.

Reply 1661

nathaan5

hi, in the spec it says 'be able to perform calculations for the titrations of
monoprotic and diprotic acids with sodium hydroxide, based
on experimental results' im stuck on this so can anyone offer any help!?

e.g In a titration we find that the equivalence point is reached when 25cm3 of 0.0150 mol dm-3 NaOH is neutralised by 15.0cm3 HCL. what is the conc of the acid?

and what else do we need to know for titrations? Thanks :biggrin:

Reply 1662

lochbeau

Can anyone link me a paper with all correct answers and working for January 2012? Can't learn anything from a mark scheme... would be greatly appreciated.

Reply 1663

Disney0702

Original post by Besakt

M1 x V1 = M2 x V2

0.154 x 10 = M2 x (total volume which is 990cm3 + 10 cm3 = 1000cm3)

then you do (0.154 x 10)/1000

Which gives M2 to be 1.54 x10-3 so [H+] = 1.54 x10-3

then you just -log it to find ph

Hi there!

I am going to sit the CHEM4 exam this June and I was looking at this paper for revision and was so clueless.

Your explanation really helped, thanks a lot :h:

Reply 1664

lucy2506

Can anybody help me how I am able to find the rate of a reaction from a graph

Reply 1665

lucy2506

Has anybody got the june 2014 paper too?

Reply 1666

Arshii

hey guys! has anyone done anything on the chem4 isa's ..? from what i know its likely to be on kinetics ..

Reply 1667

Disney0702

Original post by I.LoveSyria.Aleppo

What topics are most likely to come up on this exam?
Whats not on the past papers?

This was posted from The Student Room's Android App on my GT-S5830

There's definitely going to be Acids and Bases questions and I'm pretty sure there'll be at least one Organic mechanism question, they usually throw that in too.

I'm also expecting route synthesis.

I don't what topic hasn't come up from the past papers because I haven't done them all yet. :colondollar: