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Edexcel a2 chemistry revision for the may/june 2012 exam :)

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Original post by wam-bam
why doesn't [Zn(NH3)6]4+ ever form


NH3 has no overall a charge, the only ion of Zinc is a 2+ ion, so this 4+ complex could never form as Zn^4+ doesn't exist.
Reply 21
Original post by NutterFrutter
NH3 has no overall a charge, the only ion of Zinc is a 2+ ion, so this 4+ complex could never form as Zn^4+ doesn't exist.


okay so my question is more why can't Zn form 6 ligands with NH3 but it can form [Zn(NH3)4(H2O)2] happily??
Reply 22
guys i feel so scared & nervous for unit 5 chem :frown:
I really cant understand it.... any suggestions or tips on how to go about it ?
Original post by aqua05
guys i feel so scared & nervous for unit 5 chem :frown:
I really cant understand it.... any suggestions or tips on how to go about it ?


What don't you understand? The difficulty of the unit 5 content is about the same as unit 4, there is just quite a bit more to learn.
Reply 24
Original post by NutterFrutter
What don't you understand? The difficulty of the unit 5 content is about the same as unit 4, there is just quite a bit more to learn.


I really dont know :frown:
I was just going through & i feel really lost... how do you study chem ?
Original post by aqua05
I really dont know :frown:
I was just going through & i feel really lost... how do you study chem ?


Colourful notes, lots of past paper questions.
Reply 26
Original post by NutterFrutter
Colourful notes, lots of past paper questions.


You studying the old syllabus papers as well ?
Are there chem salters nuffield papers ? Just wondering :s-smilie:
What resources are you using to study ?

I;m so sorry for asking you so many questions... its just that i'm really tensed
Original post by aqua05
You studying the old syllabus papers as well ?
Are there chem salters nuffield papers ? Just wondering :s-smilie:
What resources are you using to study ?

I;m so sorry for asking you so many questions... its just that i'm really tensed


I'm going to start doing the salters nufffield papers during holidays. Then official edexcel in early mayish.
facer book is alright but it gets confusing at times.
Look at your syllabus and tick off what you know and don't know. That'll make it easier for you. (I need to do this at some point too :colondollar: )
Reply 28
Hello,
Can someone help me how to write the formula for complex ions ? :s-smilie:
I have forgotten :/
For instance if we are given the metal cation Fe3+, ligand(CN-) & co-ordination number (6)...how do we get the formula as [Fe(CN)6]4-
Reply 29
Original post by raheem94
I agree with you, the edexcel text book isn't any good.

George facer is the best.

I don't know about any revision guides, i didn't used those things. But i do advice to do a lot of past papers, even the old ones. Don't do the questions(in the old past papers) which are not in the spec, if you are not sure which type of questions aren't in the new spec then ask your teacher.

Also use the mark scheme a lot for chemistry, i will advice you to learn the definitions and details about reactions, like conditions etc from the mark scheme. Books don't always give the same conditions for reactions, they differ, so it will be best to use the mark scheme to ensure that what you are learning is correct.

Also don't take A2 chemistry as easy as AS chemistry, A2 is much harder than AS.

By the way, i am not taking any exams in chemistry. I did edexcel chemistry last year, achieved an A* :smile: (AS: 300/300 A2 272/300).

Best of luck for your exams:smile:


Heyyy, congratulations on your A* you must be a genius. Would you recommend the cgp book because I am not sure whether or not I should buy it. Also did you revise using flashcards and that sort.
Thanks :smile:
Reply 30
Original post by Cyber123
Heyyy, congratulations on your A* you must be a genius. Would you recommend the cgp book because I am not sure whether or not I should buy it. Also did you revise using flashcards and that sort.
Thanks :smile:


Thanks, but i am not a genius. Getting an A* is not a very big deal.

I didn't used any of those, cgp book and flashcards.

I don't have any idea about the cgp book, i have never seen it.

I did a lot of past papers, of the complete decade. Actually i don't like chemistry very much, i like maths, so it was tough for me to concentrate on chemistry. But in the end when the exam neared then i got serious about chemistry and studied everything then practiced a decade of past papers. So as i did the past papers late, hence i didn't needed to do any revision, as everything was in my mind.
(edited 12 years ago)
Original post by aqua05
Hello,
Can someone help me how to write the formula for complex ions ? :s-smilie:
I have forgotten :/
For instance if we are given the metal cation Fe3+, ligand(CN-) & co-ordination number (6)...how do we get the formula as [Fe(CN)6]4-


Surely, it'd be [Fe(CN)6]3-

The coordination number tells you the number of dative covalent bonds that form, in this case you know there are 6 dative covalent bonds and so you will have 6 ligands of CN- (remember CN- is monodentate).

Put it all together and you get [Fe(CN)6]3-, the overall charge is 3- because +3 + (-6) = -3.
Reply 32
Original post by NutterFrutter
Surely, it'd be [Fe(CN)6]3-

The coordination number tells you the number of dative covalent bonds that form, in this case you know there are 6 dative covalent bonds and so you will have 6 ligands of CN- (remember CN- is monodentate).

Put it all together and you get [Fe(CN)6]3-, the overall charge is 3- because +3 + (-6) = -3.


why did you put a -ve sign around the 6 when calculating the overall charge ?
Original post by aqua05
why did you put a -ve sign around the 6 when calculating the overall charge ?


The Cyano group is CN-.
Reply 34
Original post by NutterFrutter
The Cyano group is CN-.


aaaaww...thankss :biggrin:
Reply 35
can someone please help me out with the transition element bit.. the place where they form complex ions & stuff...its so mega confusing!
Original post by aqua05
can someone please help me out with the transition element bit.. the place where they form complex ions & stuff...its so mega confusing!


Need more details...
Reply 37
heey...can someone please help me with calculating the errors...as in when are we suppose to multiply by 2?
I need help in apparatus such as burette, pipette, thermometer and balance...
Thank you :smile:
Reply 38
Original post by NutterFrutter
Need more details...



oh gosh! i just read this post... i solved my problems with my teacher.. im okay with it :smile:
Thanksssss :biggrin:
Reply 39
Original post by Cetacea
Hi, I'm taking Edexcel Unit 4 and Unit 5 in June 2012. Starting making revision notes/mindmaps now using the Edexcel student's book, George Facer Book and CGP book.

If anyone's interested in some good online resources for A2 Chemistry:
-Chemguide
-Knockhardy
-Rod Beavon's pages (chief examiner)
-Tips on surviving your Chemistry A-Level, written by a successful student

I'm doing Unit 5 in class at the moment - doing electrochemistry/redox and organic synthesis. Transition metals, arenes and organic nitrogen chemistry all done!

Good luck!


thanks :smile:

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