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Aqa chem 4/ chem 5 june 2016 thread

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Original post by GO97
Does anyone here know exactly which colours we have to know for transition metals in this exam? ive learnt most of the common ones


learn all of them. Seriously it'll only take an hour in total. If you repeat them to urself maybe every hour then they should be in your head. They could ask anything and especially with how chem 4 was I don't think you should leave the memory part down to chance.
Original post by emma_1111
Is lattice dissociation always -ve?


it should be positive? since energy is supplied to break the lattice
Original post by emma_1111
Is lattice dissociation always -ve?


it's always +ve
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Original post by SirRaza97
learn all of them. Seriously it'll only take an hour in total. If you repeat them to urself maybe every hour then they should be in your head. They could ask anything and especially with how chem 4 was I don't think you should leave the memory part down to chance.


like every possible colour? im more than willing to learn every colour on the spec but i dont really have a source to study them, revision guide doesnt give them all and i cant find a useful site. Do you have any recommendations?
Thanks guys! ^^^^^


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can someone list down all the cells we need to know
Original post by GO97
like every possible colour? im more than willing to learn every colour on the spec but i dont really have a source to study them, revision guide doesnt give them all and i cant find a useful site. Do you have any recommendations?

http://www.cram.com/flashcards/transition-metal-complexes-colours-6839469
I made these.
I haven't written solution or precipitate on all of them and some of them may say precipitate instead of solution. But the one's with charges are solutions and the ones without are precipitates
thanks everyone!!
Original post by GO97
like every possible colour? im more than willing to learn every colour on the spec but i dont really have a source to study them, revision guide doesnt give them all and i cant find a useful site. Do you have any recommendations?


Know the 4 precipitation reactions

Let x be (H2O)6

Cux pale blue
Cox pale pink
Fe2+x pale green
Fe3+ yellow

Cu(oh)2 blue
Cu(oh)2 blue
Fe(oh)2 green
Fe(oh)3 orange

Cucl4 yellow
Cocl4 blue

Cu(nh3)4(h2o)2 deep blue

Kmno4 oxidizing agent is purple and turns. Colour less at end point

Acidified potass di chrome

Orange to green
Original post by flylikeafly
can someone list down all the cells we need to know


None.

Except hydrogen-oxygen fuel cell.

You need to know that only the feasible reaction occurs in rechargeable (primary) cells and that rechargeable (secondary) cells can be recharged and discharged
Al2O3 + H2O ---> ?
Can someone explain 7c pls
http://filestore.aqa.org.uk/subjects/AQA-CHEM5-QP-JAN13.PDF
(edited 7 years ago)
Original post by GO97
like every possible colour? im more than willing to learn every colour on the spec but i dont really have a source to study them, revision guide doesnt give them all and i cant find a useful site. Do you have any recommendations?


This is my table I use. Note that the Aluminum column isnt filled in completely. It's mostly white ppt apart from when it's an aqua ion or when it readcts with excess OH where it's colourless solution. Oh and ignore the CO i put in the Fe3+ coloumn for excess nh3:

(edited 7 years ago)
Original post by badaman
Al2O3 + H2O ---> ?


Does not dissolve in water cus of high strength of Al2O3 lattice.
Original post by Super199
Can someone explain 7c pls


7c what?
Original post by Suits101
None.

Except hydrogen-oxygen fuel cell.

You need to know that only the feasible reaction occurs in rechargeable (primary) cells and that rechargeable (secondary) cells can be recharged and discharged


You know when they ask why this cell is not rechargeable or ammeter reading would fall to zero. I don't understand that.
Original post by SirRaza97
7c what?


Check again g
Can anyone help me out on this question image.jpg
Original post by SirRaza97
This is my table I use. Note that the Aluminum column isnt filled in completely. It's mostly white ppt apart from when it's an aqua ion or when it readcts with excess OH where it's colourless solution. Oh and ignore the CO i put in the Fe3+ coloumn for excess nh3:



You don't need every colour spec specifically states fe cu and co in ppt reactions and cu nh3 deep blue cucl4 and cocl4
Original post by Super199


E Au+(/Au) > E O2(/H2O)
So H2O reduces Au+ ions to Au so they are not normally found in aqueous solutions.
Combine Half Equation 1 and 2 (Times 1st one by 2) to get:
2Au+ + H2O → 2Au + 1/2O2 + 2H+

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