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AQA - Unit 5 - Energetics, Redox and Inorganic Chemistry

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Reply 1560
Avatar for lou12
lou12
Original post by artykid23
wooo nice :smile: and the the entropy just times the entropies by its coefficients
and then -45 -(800x delta S/1000)? and then positive g so not feasible>


hope so coz i thats what i did:smile:
Original post by artykid23
wooo nice :smile: and the the entropy just times the entropies by its coefficients
and then -45 -(800x delta S/1000)? and then positive g so not feasible>


If I recall correctly, the enthalpy was -36kJmol^-1

and yeah, you should have got about -99.5 for the change in entropy I believe (I forgot to divide by two for the entropy, but remembered for the enthalpy, fml)
Fe3_ more acidic?
Fe3 with carbonate?
lead acid cell?
Palladium shapes etc?????
Original post by artykid23
Fe3_ more acidic?
Fe3 with carbonate?
lead acid cell?
Palladium shapes etc?????


Palladium shapes were Tetrahedral and Square Planar.
Right, did anyone else get thrown on the Aluminium reactions with HCL and NaOH? because the question said 'Ionic equation' but i don't remember learning the actual production of OH- or H+ ions and all that so I just wrote the equations as we've learnt?
But overall a very nice paper, section B was a definite treat, but as normal plenty of little obscure questions to trip you up. FREEDOM!
Reply 1565
Avatar for lou12
lou12
Original post by artykid23
Fe3_ more acidic?
Fe3 with carbonate?
lead acid cell?
Palladium shapes etc?????


can i just ask, for the delta G question you just asked me about, i used the mean bond enthalpy value of -36 when i worked out delta G. do you think i'll lose all the marks for this?
Original post by lou12
can i just ask, for the delta G question you just asked me about, i used the mean bond enthalpy value of -36 when i worked out delta G. do you think i'll lose all the marks for this?


you will probably get error carried forward...its was out of 3 marks so i think it would be 1 for g= h-ts, 1 for answer and 1 for units so might lose 1?
Reply 1567
Avatar for lou12
lou12
:smile:
Original post by artykid23
you will probably get error carried forward...its was out of 3 marks so i think it would be 1 for g= h-ts, 1 for answer and 1 for units so might lose 1?


cool. it still gave a positive delta G though, so i wont lose that mark:smile:
what was the acid lead equation?
Original post by artykid23
what was the acid lead equation?


I'd like to know this too.

I think mine ended up being really short as you could cancel loads out. :rolleyes:
Original post by jimmy303
Octahedral shape yes and the C2O4(2-) form a square planar without the two waters yes because it said the waters were opposite each other.

120 degrees because http://en.wikipedia.org/wiki/Oxalate the carbons are bonded to three things then its trigonal planar, so unless i misread the question (i thought it wanted the bond angle between carbon and the oxygen) then i think it's 120 degrees.

If it asked for bond angles of the coordinate bonds with the metal ion then I'm wrong :P


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
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


That's what I put.
I messed this up so badly :/ I panicked and just forgot everything I learned and messed up all the big questions! And I didn't learn all the recharging etc etc, so I messed that up too! How many marks can you afford to lose to still get an A?
Original post by Seasick Steve
Also, there was another weird question like "describe an experiment to show that Aluminium oxide contained ions?" I really just put down random rubbish there just as the invigilator told us to put our pens down.


I put about electrolysis in molten cryolite and Al going to cathode with O2 forming at the anode, think it's the process for getting Aluminium from it's ore
Reply 1574
Avatar for kabolin
kabolin
9
Original post by Willyg11
Was the enthalpy of solution negative or positive?

Also was the best reducing agent Zinc?

Only one colour! annoying!


i wrote zn2+??????????????????
Original post by lou12

Original post by lou12
dammit. i put hydrogen fuel cell


but wouldnt the emf of the standard hydrogen cell equal to 0.00v?
Reply 1576
Avatar for Betsss
Betsss
would "hydrogen oxygen" fuel cell be ok?
and the reason was, the electrons and hydrogen ions produced at the anode, by oxidation of H2, is recirculated to the cathode; so the emf doesnt go down?
what did people get for the KO2, H+ / O2 cell diagram?
Original post by Betsss
would "hydrogen oxygen" fuel cell be ok?
and the reason was, the electrons and hydrogen ions produced at the anode, by oxidation of H2, is recirculated to the cathode; so the emf doesnt go down?


I suspect so. The reason is that the reactants are constantly supplied to the fuel cell, i.e. hydrogen and oxygen are constantly pumped in so the cell doesn't require recharging and the reactants stay at a constant level (I hope at least. . .)
Reply 1579
Avatar for ef8888
ef8888
Was it just me or the paper didn't have a question where they ask you the colour of a certain complex right?? There was one about why it is coloured but they didnt actually ask us any actual colours??
In the Al question, did it really say ionic equations?? I put whole equation down!! Damn it!! :frown:

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