The Student Room Group

AQA - Unit 5 - Energetics, Redox and Inorganic Chemistry

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Reply 1700
Original post by lemontang1
yh


right ok..

well basically they gave us the formation enthalpy and the two enthalpies of hydration (or was it solution?)

you had to add them together BUT you had to change the sign for the formation enthalpy, as you have to dissociate the lattice and then hydrate it..

think it was -51??
Original post by Zakir
right ok..

well basically they gave us the formation enthalpy and the two enthalpies of hydration (or was it solution?)

you had to add them together BUT you had to change the sign for the formation enthalpy, as you have to dissociate the lattice and then hydrate it..

think it was -51??


Thanks, think I did that....also on the second page if forgot to half the equations, will that have mucked up every question on that page???
Reply 1702
Original post by lemontang1
Thanks, think I did that....also on the second page if forgot to half the equations, will that have mucked up every question on that page???


i forgot to half the equations also...but only on the first bit..

i think if you showed the formule (bonds broken - formed) and ( products - reactants) then we should get the mark for that...if we're luck we might even get method marks to show that we knew what to do..

so hopefully you won't have mucked it all up :smile:
Original post by Zakir
i forgot to half the equations also...but only on the first bit..

i think if you showed the formule (bonds broken - formed) and ( products - reactants) then we should get the mark for that...if we're luck we might even get method marks to show that we knew what to do..

so hopefully you won't have mucked it all up :smile:


You know on the second bit of this...about finding delta G...etc, I cant really remember it...did we have to use the equation on this...i cant remember???
Reply 1704
Original post by lemontang1
You know on the second bit of this...about finding delta G...etc, I cant really remember it...did we have to use the equation on this...i cant remember???


i think we had to use the delta S value we calculated and the delta H value they gave us (-46)...

nope we didn't have to use the equation :smile:

what answers did you get?
Original post by Zakir
i think we had to use the delta S value we calculated and the delta H value they gave us (-46)...

nope we didn't have to use the equation :smile:

what answers did you get?


I cant remember my answers at all.... thats whats making me panic!! I always seem to make loads of stupid mistakes on exams, even when I know how to do it.
Original post by Zakir
i think we had to use the delta S value we calculated and the delta H value they gave us (-46)...

nope we didn't have to use the equation :smile:

what answers did you get?


Also, sorry to be a pain....but how did you calculate the delta delta s value???
Reply 1707
Original post by lemontang1
I cant remember my answers at all.... thats whats making me panic!! I always seem to make loads of stupid mistakes on exams, even when I know how to do it.


yup don't we all!

iv made quite a few VERY silly mistakes on the paper...but my methods were all good, and AQA do tend to credit that, as well as not being penalised twice for the same mistake...they carry the error forward and mark it like that..

guess thats the only good thing about AQA lol

:smile:
Reply 1708
Original post by lemontang1
Also, sorry to be a pain....but how did you calculate the delta delta s value???


its fine..

im just as worried as most the peeps on here!

well for once (lol) i read the question properly for delta S..

i realised it said one mole...

so you used the formula (products) - (reactants) <<< for the S values..

and got -99.5 i think...
Dont suppose anyone has got the paper??? I realise that ur not meant to give them out, etc, before anyone gives me neg rep!!
Reply 1710
someone did mention on here that they had the paper...

don't know if they're in the process of putting it up..
Original post by kingjohno
The waters go above and below a single plane. On the plane, two molecules of C2)4 bond twice (as bidentate), thus the angle between each o-Cu-o is 90o


Like i said I misread the question. I know the bond angles of o-Cu-o would be 90 degrees, I was talking about the bond angles on the ethane dioate ligands themselves.
After reading this I reckon I've done awful, made a few really stupid mistakes like the ionic equations instead of full etc.... and the thing is I knew the ionic :frown:
Reply 1713
If the paper is marked online and each question is marked by a diffrent person how are you ment to get error carried forward.
Original post by Wish I Could Change This
After reading this I reckon I've done awful, made a few really stupid mistakes like the ionic equations instead of full etc.... and the thing is I knew the ionic :frown:


It's easier to remember the stuff you got wrong and not remember the stuff you got right, especially since the people of TSR have a habit of discussing the harder questions. An A in this unit is usually around 70% of the exam. That means it's possible to drop around 30 marks and still do brilliantly. I'm sure you did more than fine :smile:

Let it go since there's nothing you can do about it now. Focus on the exams you've got left or if you're lucky enough to have finished them already go and enjoy the sunshine with friends! :tongue:
(edited 12 years ago)
What do people think the grade boundaries will be? And if 80% of 120ums is 95ish, is that what you should get if you get like bang on the A boundary?
Original post by jimmy303
It's easier to remember the stuff you got wrong and not remember the stuff you got right, especially since the people of TSR have a habit of discussing the harder questions. An A in this unit is usually around 70% of the exam. That means it's possible to drop around 30 marks and still do brilliantly. I'm sure you did more than fine :smile:

Let it go since there's nothing you can do about it now. Focus on the exams you've got left or if you're lucky enough to have finished them already go and enjoy the sunshine with friends! :tongue:


I'm going to keep my hopes up then, thank you :biggrin:
any idea how much you could drop for an A*? I was under the impression it was 80% for an A and 90 for an A*
What did you guys get for the Pb electrode question?
Original post by Wish I Could Change This
I'm going to keep my hopes up then, thank you :biggrin:
any idea how much you could drop for an A*? I was under the impression it was 80% for an A and 90 for an A*


Yeah, you are correct in terms of UMS:

90% --> A*
80% --> A

But normally on chem5 it is 70% raw marks for 80% ums.
Original post by fsaeed20
If the paper is marked online and each question is marked by a diffrent person how are you ment to get error carried forward.


I'm pretty sure that if they were marked by more than one person, atleast a whole question will be marked by an individual person.

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