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

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Can anyone help me with question 6, specimen paper 1? Thanks~

I was doing past papers and was getting pretty decent results now I've just tried the set 2 specimen papers and OH MY GOD they are so hard euugh

Reply 122

The Panic Queen

Original post by 123chem

Can anyone help me with question 6, specimen paper 1? Thanks~

first you work out the number of moles of HCL so
n=0.2x (50/1000)= 0.01
now you know this you know that the moles of ca(OH)2 is half of this
0.01/2 =5x10^-3
now work out the mass of ca(OH)2 - mass=moles/mr
5x10^-3x74.1=0.371
therefore, mass must be less than this amount

You need to now outline practcal details
1)Measure 50cm3 of acid using a burette
2)Transfer this into a conical flask
3)Add the weighed solid. Add the indicator
4)titrate using 0.2 moldm-1 NAOH
5)Record volume once indicator changes colour
6)Calculate moles NAOH which is equal to the moles of HCL

Hope this helps :smile:

Reply 123

rosemondtan

Hey guys! What did you all learn for ionisation in time of flight mass spectrometry? Are the samples bombarded with high energy electrons or protonated by adding a H+?

Reply 124

Science_help

Original post by rosemondtan

Hey guys! What did you all learn for ionisation in time of flight mass spectrometry? Are the samples bombarded with high energy electrons or protonated by adding a H+?

This should help, these are very recent and updated.

http://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS.PDF

http://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS-QA.PDF

Reply 125

emilysmith268

the chem2 past papers are so long wtf why are they 100 marks? I feel exhausted after doing one

Reply 126

G2S

Does anyone know which practicals we have to know about?

Reply 127

sameer99

wishing you guys all the best for Paper 1 and Paper 2 :smile:

Reply 128

The Panic Queen

Original post by G2S

Does anyone know which practicals we have to know about?

All 6 that you've done this year :smile:

Reply 129

G2S

Original post by The Panic Queen

All 6 that you've done this year :smile:

Could you name them all for me please

Reply 130

The Panic Queen

Original post by G2S

Could you name them all for me please

http://www.aqa.org.uk/subjects/science/as-and-a-level/chemistry-7404-7405/a-level-practical-assessment

Scroll down a bit and there is a table with them all in (The first 6 are just for AS)

Reply 131

champ_mc99

Is kinetics in the first exam??

Reply 132

ajsullivan

Can I suggest you check out www.scienceskool.co.uk

There are model answers for the version 2 specimen papers on there as well as lots of others notes, questions etc.

Hope it helps!

Alex

Reply 133

itvvnews

do you guys think they will ask about the dehydration of cyclohexanol in paper 1?
spec says relevant practical skills and cyclohexanol is organic therefore should be in paper 2 right?

Reply 134

0161maria

Original post by champ_mc99

Is kinetics in the first exam??

it is not.

Paper 1 topics:
- atomic structure
- amount of substance
- bonding
- energetics
- equilibria (including Kc)
- redox
- periodicity
- group 2
- group 7
- practicals

Paper 2 topics:
- amount of substance
- bonding
- kinetics
- energetics
- equilibria (including Kc)
- practicals
- all organic chem (6 topics)

Reply 135

angellll

Original post by champ_mc99

Is kinetics in the first exam??

nope

Reply 136

angellll

Who else found the specimen papers extremely difficult :frown:

Feeling so demotivated right now.

Reply 137

haes

Original post by rosemondtan

Hey guys! What did you all learn for ionisation in time of flight mass spectrometry? Are the samples bombarded with high energy electrons or protonated by adding a H+?

You should know both! For questions asking about ionisation they usually accept either but I think from now on they're going to be more specific and ask you something like "How are the samples ionised in electrospray ionisation(protonation) / electron impact(with electron gun)?"