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AQA CHEM5 A2 Chemistry - 19th June 2013

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The oxygen doesn't balance in the overall MnO4- equation. And what happened to the H2O2 when you combined both half equations?

my bad. missed the 5h2o2. then it balances.

Reply 981

SamEastie

Original post by Vip3rgt9

Thank you very much, I couldn't find these anywhere on the internet.

Original post by Zazuwaved

Thanks very much =)

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i missed the 5H2O2 off on mno4- by accident! sorry. ive edited it now.

Reply 982

A sheesh

right, has ANYONE GOT A DOCUMENT OF ALL THE EQUATIONS FOR COLOURS AND COLOUR CHANGE?
Pi keep getting 70-80 on papers but lose around 10 on colours

Reply 983

xoxoxoxoxox

hey guys.. would knowledge of mechanisms be required for unit 5..
also.. would be need to revise unit 4 . unit being synoptic and all..

Reply 984

gingerandice

how do you balance redox equations involving hydroxide ions?

Reply 985

cuckoo99

Original post by xoxoxoxoxox

hey guys.. would knowledge of mechanisms be required for unit 5..
also.. would be need to revise unit 4 . unit being synoptic and all..

knowledge of the whole course is required for unit5. so all manners of organic/ inoranic/ physical and analytical chemistry :wink:

mechanism can come up in otherwords lol

Reply 986

simanana

hey can any one help?

In my aqa text book at says at one point that [Co(NH₃)₆]³⁺(aq) is formed by oxidation of [Co(NH₃)₆]²⁺and that this is yellow.

However in chapter 16.3 it says that [Co(NH₃)₆]²⁺ may be oxidised to air to a dark brown mixture containing Co(III) compounds.

So why does oxidation of the same compound form two different colours?

Reply 987

Chris-69

Original post by cuckoo99

knowledge of the whole course is required for unit5. so all manners of organic/ inoranic/ physical and analytical chemistry :wink:

mechanism can come up in otherwords lol

And where did you read that? Because it's not true lol.

Reply 988

mathsguy

Original post by cuckoo99

knowledge of the whole course is required for unit5. so all manners of organic/ inoranic/ physical and analytical chemistry :wink:

mechanism can come up in otherwords lol

Not true, certain aspects from unit 1 and 2 can come up in unit 5. No unit 4. :-)

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Reply 989

cuckoo99

Original post by mathsguy

Not true, certain aspects from unit 1 and 2 can come up in unit 5. No unit 4. :-)

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i have a question right infront of me that says "name and outline the mechanism for this reaction" also has some bronstead-lowry acid base theory

Reply 990

Sherlockedd

Original post by cuckoo99

i have a question right infront of me that says "name and outline the mechanism for this reaction" also has some bronstead-lowry acid base theory

It's probably old spec :wink:

Reply 991

cuckoo99

Original post by Chris-69

And where did you read that? Because it's not true lol.

my teacher told me and i have a unit 5 past paper infront of me with organic chemistry in it

Reply 992

cuckoo99

Original post by Sherlockedd

It's probably old spec :wink:

hmm maybe it is a 2008 paper but that means my teacher was wrong lol

Reply 993

Sherlockedd

Original post by cuckoo99

hmm maybe it is a 2008 paper but that means my teacher was wrong lol

Yeah 2008 is old spec, new spec won't combine U4 and U5 :smile:

(and usually they'll combine U4 with U2 and U5 with U1, although that's not a strict rule, it's just what fits better content wise)

Reply 994

Chris-69

Original post by cuckoo99

my teacher told me and i have a unit 5 past paper infront of me with organic chemistry in it

You're probably doing an old paper. And you're teacher is wrong, the AQA specification from there website says that the units are not synoptic and that your can do unit 5 and 4 in which order (i.e Unit 5 could be done in Jan and Unit 4 in June).

Reply 995

Smartass

Can someone explain chromatography column and gassbpleae exams tomorrow

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Reply 996

cuckoo99

Original post by Smartass

Can someone explain chromatography column and gassbpleae exams tomorrow

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check the unit 4 thread , i posted an explanation there at around page 13 ish of the thread

Reply 997

idunnotbh

hey guys random question here but can anyone confirm this for me please...

we do NOT have to learn the half equations and overall equations of re chargeable batteries and non re chargeable batteries, for example for lead acid batteries or zinc/carbon like in the text book?

thank you

Reply 998

melony852