AQA CHEM4 and CHEM5 revision thread 2016

Original post by Anon_98

I don't think I can remember what the exam questions consisted of anymore tbh + what I properly thought of it bc it was quite a while ago + I've had quite a few since then.

Hm, how irritating. I think it was alright though? We had that double titration calculation stuff at the beginning I think..which was quite nice then a 2 marker crystallization question at the end. - I don't know what was in between. >.<

What about you?

I personally found it okay, but I'm sure people would've messed up that Vanadium redox potential question, as well as the question about calibrating a ph probe then how you would use the results (interpolate calibration curve) and the nickel complex question was pretty weird!

Reply 22

thenextchemist

21

Original post by Engineerrookie

I personally found it okay, but I'm sure people would've messed up that Vanadium redox potential question, as well as the question about calibrating a ph probe then how you would use the results (interpolate calibration curve) and the nickel complex question was pretty weird!

Yeah
I found it pretty difficult tbh
I'm hoping grade boundaries would be low but I don't think that's likely

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Reply 23

Engineerrookie

Original post by Bloom77

Yeah
I found it pretty difficult tbh
I'm hoping grade boundaries would be low but I don't think that's likely

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What are you hoping for in Chem? I guess it's only a small percentage of the a level so don't worry!

Reply 24

thenextchemist

21

Original post by Engineerrookie

What are you hoping for in Chem? I guess it's only a small percentage of the a level so don't worry!

Hoping for an A!
But aiming for an A* as it might be what I do at uni.
I got a B in AS so I retook the unit 1 module only.

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Reply 25

123456789012

11

A few tips from me (since I've already had the pleasure of doing these exams :tongue:

).. never try to memorise something if you don't get it (might sound a little obvious to some); ask your teachers, use the internet, textbooks, or any other means, and make sure the understanding is absolutely clear.. once you've done that, move on to past papers: do as many papers you can get hold of, and highlight any challenging questions so you can visit them again near the exam period. Making revision notes isn't necessary in my opinion, at least not for me because I just felt making them would have been a waste of time.. but if they work for you, then go for it!

The only aim of this post is to encourage everyone taking these exams.. there's no doubt these exams are tough, but with practice it's not going to be as bad as some people might make it out to be.

Spoiler

(edited 7 years ago)

Reply 26

rxns_00

15

Anyone got anything on organic synthesis? I can't deal with it man, I have no clue when it comes to answering a synthesis question lol

Reply 27

peterpotatoes

5

Original post by Anon_98

Yeah, it's such a big topic aha. Aw I mean, it feels a little tedious at first but I find it really fun learning all the colours + reactions so I think that makes it easier + my notes for it are super pretty too which helps. :colondollar:

Make some pretty notes! I also think it's more manageable if you split it up into sub-sections. So I've got it like:

- properties+ characteristics
- Complex formation
- Unidentate/Bidentate/Multidentate
-Naming cationic complexes
- Naming anionic complexes
- Stereochemistry
- Ligand substitution reactions
- Reactions of metal-aqua ions in solution.
- Transition metals as catalysts.
- Colour of ions + Spectrophotometry.

It's the only topic I've made notes on so far lol. I'd recommend that you make your notes on each section + then learn each individual sub-section. I think the easiest way to learn the reactions is by grouping them in pairs. I don't know what works for you, but since there are 6 elements to remember ( Copper, Cobalt, Iron(II), Iron (III), Chromium, Aluminium) I grouped Copper + Cobalt. Then I grouped the two Irons and I grouped Chromium + Aluminium which is all based on the reactions that take place.

I'm not sure that all makes much sense. :colondollar:

Oh, I literally haven't done any Biology revision whatsoever. I have zero knowledge on it. Like, absolutely zero.- I genuinely don't even know what I've learnt this year bar light independent reactions + the worst thing is, it's my weakest subject so I should really be spending much more time on it. I guess I prefer Unit 4 though bc I don't know anything in Unit 5. What about you?

Thank you for the luck! I also did AS physics last year, I totally agree with that judgement. Thankfully I picked Statistics as my module though, which isn't quite as bad. (':

Thanks so much for your tips on transition metals! I'll be sure to write up some pretty notes on those and hopefully it'll help a bit. Especially grouping the metals together, that sounds like it would work really well.

I think biology is really not about content. Obviously, you need the foundation of content to build upon but I'm sure you're aware that it's all about application of knowledge, especially at A2. If you can do that and data/math questions, I'm sure you'll be okay.

I much prefer unit 5 to unit 4 - it's so much more interesting! Unit 4 doesn't even feel like biology to me :/

I've heard statistics is a lot easier than mechanics, hope it goes well for you! :smile:

Reply 28

Engineerrookie

Original post by Bloom77

Hoping for an A!
But aiming for an A* as it might be what I do at uni.
I got a B in AS so I retook the unit 1 module only.

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Same here, although I'm retaking unit 1 and unit 2, it says on the specification that unit 2 is 23% of our a level and each A2 module is just 20%?! I'm pretty sure I won't be getting an A* but I know it's only about around 85/100 to get an A* in unit 5 so it doesn't seem to bad :smile:

Reply 29

6. (a) (i) Draw a fully-labelled Born–Haber cycle forthe formation of solid barium chloride, BaCl2, from its elements.Include state symbols for all species involved.
(ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1 Ive had a go at this Q and know the answer to it - it came up as -347kj/mol which was half the value initially got of -695 - so i missed the step to half that value but i dont understand why i need to half it? (ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1

Reply 30

sorry the message messed up
Ive had a go at this Q and know the answer to it - it came up as -347kj/mol which was half the value initially got of -695 - so i missed the step to half that value but i dont understand why i need to half it? (ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine.

Reply 31

ReviewTag

Does anyone have any useful resources for learning all of the colours/ transition metal equations? Thanks!

Reply 32

ajsullivan

8

Original post by ReviewTag

Does anyone have any useful resources for learning all of the colours/ transition metal equations? Thanks!

Check out www.scienceskool.co.uk

Specifically: http://www.scienceskool.co.uk/unit-5.html and then colour of complexes. Might help you visualise it a little easier.

Good luck!

Reply 33

peterpotatoes

5

Original post by ajsullivan

Check out www.scienceskool.co.uk

Specifically: http://www.scienceskool.co.uk/unit-5.html and then colour of complexes. Might help you visualise it a little easier.

Good luck!

Can I just say thanks so much for this! It was a massive help for simplifying the transition metal reactions and colours

Reply 34

Could someone possible help answer my Q on this thread?

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Reply 35

Signorina

Original post by ahsan_ijaz

6. (a) (i) Draw a fully-labelled Born–Haber cycle forthe formation of solid barium chloride, BaCl2, from its elements.Include state symbols for all species involved.
(ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1 Ive had a go at this Q and know the answer to it - it came up as -347kj/mol which was half the value initially got of -695 - so i missed the step to half that value but i dont understand why i need to half it? (ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1

Because the value you got (-695 kj mol-1) is the electron affinity of chlorine x 2. You had 2Cl(g). Electron affinity is energy change when ONE mole of gaseous atoms gains one mole of electrons.

Therefore you need to divide -695 by 2

Reply 36

Original post by Signorina

Because the value you got (-695 kj mol-1) is the electron affinity of chlorine x 2. You had 2Cl(g). Electron affinity is energy change when ONE mole of gaseous atoms gains one mole of electrons.

Therefore you need to divide -695 by 2

Thanks thats fine but the molecule is bacl2? so considering it has 2 chlorine which would have to be 2cl- thus wouldnt you have 2 electron affinities?

Reply 37

Signorina