Aqa chem 4/ chem 5 june 2016 thread

Scroll to see replies

Reply 2140

Ejsjwwj

Original post by GO97

what does this mean? sorry if i sound stupid

I have have no idea myself 😅 but i think its another way of saying theyre spherical

Reply 2141

vish.handa

Original post by GO97

im not well informed on the perfect ionic model theory can someone who knows it well bullet point the key ideas

It assumes ions are perfectly spherical
Assumes no covalent character
Real value may be more negative (I think) because of any covalent character present
(the negative thing check, It may be more positive)

Reply 2142

vish.handa

Original post by GO97

what does this mean? sorry if i sound stupid

Not sure about chem but in Physics point charge means the entire charge acts froma singlular point (rather than enitre ion) like the centre of mass , rather the centre of charge

Reply 2143

Kikstar

Hi! Could someone PLEASE tell me how you know if there will be a further reaction, if given E theta values of electrochemical cells? I'm feverishly trying to look through notes haha

Posted from TSR Mobile

Reply 2144

GO97

Original post by vish.handa

Not sure about chem but in Physics point charge means the entire charge acts froma singlular point (rather than enitre ion) like the centre of mass , rather the centre of charge

ah okay i dont do physics lol but that sounds like its assuming that there is no distortion in the charge, similar to what jmedi said

Reply 2145

Jmedi

Original post by GO97

ah okay i dont do physics lol but that sounds like its assuming that there is no distortion in the charge, similar to what jmedi said

Yeah it means the same thing.

Reply 2146

Aliceeee12

Hello everybody hope revisions going ok!

Just wanted 2 ask, how much do you need 2 know abt alkaline half equations like how do we know when 2 use alkaline half equations

Reply 2147

GO97

Original post by Jmedi

Yeah it means the same thing.

ok nice im grasping this now

Reply 2148

Jmedi

Original post by Aliceeee12

Hello everybody hope revisions going ok!

Just wanted 2 ask, how much do you need 2 know abt alkaline half equations like how do we know when 2 use alkaline half equations

They will tell you if it's in alkaline solution

Reply 2149

Suits101

Original post by Jmedi

There is only ionic interaction, electrostatic forces
The ions are perfect spheres (no charge cloud distortion)

no covalent character

Original post by vish.handa

I use covalent character/interaction interchangeably - is this ok? Since I've seen on markschemes for perfect ionic model they say no covalent INTERACTION

Reply 2150

GO97

so if u have more distortion of charge, then the ions are less spherical, theoretical enthalpy will be higher and there will be more covalent interactions??

(edited 7 years ago)

Reply 2151

vish.handa

Original post by GO97

so if u have more distortion of charge, then the theoretical enthalpy will be higher and there will be more covalent interactions??

well would it be more exo or endo, once you've got that in your head then no need to worry about remembering which way it goes , I dont know though haha hoping someone will pop up who knows

Reply 2152

Jmedi

Original post by vish.handa

well would it be more exo or endo, once you've got that in your head then no need to worry about remembering which way it goes , I dont know though haha hoping someone will pop up who knows

lattice dissociation would be more endothermic

Reply 2153

GO97

Original post by vish.handa

well would it be more exo or endo, once you've got that in your head then no need to worry about remembering which way it goes , I dont know though haha hoping someone will pop up who knows

i remeber my teacher always talking about the size and polarity of atoms/ions when it came to these types of questions but im not too sure how they relate(i doze in class really easily)

Reply 2154

Hopefulmedic15

Original post by Kikstar

Q7(d) in Jan 13 is a good example of this - look at the mark scheme to clarify.

Essentially one oxidising agent is strong enough to oxidise the reducing agent twice

Reply 2155

Hopefulmedic15

Original post by GO97

anything without an essay is a steal in my eyes haha. lets hope we get the grades we need

That's one of the only nice things about the paper :P

Good luck for your exams!

Reply 2156

Jmedi

Original post by GO97

i remeber my teacher always talking about the size and polarity of atoms/ions when it came to these types of questions but im not too sure how they relate(i doze in class really easily)

smaller ions increases the lattice enthalpy and so will increased charge

Reply 2157

Kikstar

Original post by Hopefulmedic15

Q7(d) in Jan 13 is a good example of this - look at the mark scheme to clarify.

Essentially one oxidising agent is strong enough to oxidise the reducing agent twice