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Reply 60
Original post by hyy
Thanks a lot. I mean it ... I've been looking for this paper for ages. :smile:

Do you know if you can get the mark scheme?



Original post by abzy1234
Only teachers have it am guessing at the moment :/

My teachers are on holiday so they aren't checking my emails pleading for the markscheme lol :tongue:

We should get it by next week hopefully :smile:

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Here you go guys:
Mark scheme F334 June 2012 :smile:
Reply 61
Original post by thegreenchildren
No worries! My teacher hasn't taught us any of steel story because he says we can just learn everything from books at home so he makes us do stupid experiments in class instead (not even important coursework ones).

Anyway, you don't need 4 coppers, you need 1 copper,this is the central metal ion, then you add 4 chlorine ligands on to it. This means it is tetrahedral in shape. Chlorine ligands are large so only 4 can fit around the central metal ion. This means the coordinate number of the complex ion is 4. H2o and OH- ligands are small so 6 of these can fit around the central metal ion, making the complex ion octahedral and the coordination number is 6.


Thanks for the help, I was confusing myself lol
The question was about EDTA^4- with copper(II) (last Q on June 2010), but I think I get it now. Does it mean that 6 lots of EDTA can fit around the copper, making it octahedral with a coordinate number of 6? (The charge on the EDTA was confusing me :s-smilie:)
Original post by super121
Thanks for the help, I was confusing myself lol
The question was about EDTA^4- with copper(II) (last Q on June 2010), but I think I get it now. Does it mean that 6 lots of EDTA can fit around the copper, making it octahedral with a coordinate number of 6? (The charge on the EDTA was confusing me :s-smilie:)


No because EDTA^4- is a single ligand but it has 6 lone pairs on it so it can make 6 coordinate bonds with the central metal ion. So it is octahedral in shape because the coordination number is 6 not because there are six ligands.

The charge on EDTA is -4 and i think you just need to remember that.

Hope that helps? :smile:
Reply 63
Original post by thegreenchildren
No because EDTA^4- is a single ligand but it has 6 lone pairs on it so it can make 6 coordinate bonds with the central metal ion. So it is octahedral in shape because the coordination number is 6 not because there are six ligands.

The charge on EDTA is -4 and i think you just need to remember that.

Hope that helps? :smile:


Thanks, that makes sense. For some stupid reason I thought the charge influenced the shape :P
I have a quick question - is there any reasons why carbonyl groups (C=O) cannot form dative covalent bonds to the central metal ion in a ligand, despite the oxygen having two lone pairs of electrons? :smile:
Reply 65
Original post by Harantony
I have a quick question - is there any reasons why carbonyl groups (C=O) cannot form dative covalent bonds to the central metal ion in a ligand, despite the oxygen having two lone pairs of electrons? :smile:


Hmm that's an interesting question. If you take the ethanedioate ion, then the lone pair of electrons are on the single bonded carbon to oxygen. I would assume that this is because the carbonyl group has the greater stability? Can the negative charge of the oxygen be spread over the carbonyl group?

Or the oxygen in the carbonyl group don't have any significant lone pairs, as they use it to form a double bond with the carbon.

Something like that I guess :tongue:
Reply 66
Original post by AmirHabeeb
Here you go guys:
Mark scheme F334 June 2012 :smile:


You're a legend. Thanks! :biggrin:
Reply 67
help please!

June 2012
Q. 3, b , ii

how are we meant to know which is tyr !?
Reply 68
Original post by StutZz
help please!

June 2012
Q. 3, b , ii

how are we meant to know which is tyr !?


It says the order of amino acids is Tyr-Gly-Ile. You should know about breaking proteins into amino acids, so do that for the first amino acid present in the protein.

If you're still stuck, look at page 27 in the revision textbook :smile:
Reply 69
Original post by abzy1234
It says the order of amino acids is Tyr-Gly-Ile. You should know about breaking proteins into amino acids, so do that for the first amino acid present in the protein.

If you're still stuck, look at page 27 in the revision textbook :smile:



yea but how do we know that if the sequence started from the left or the right of the molecule? as in, how do we know that the phenol end was the tyr one? :s
Reply 70
Original post by StutZz
yea but how do we know that if the sequence started from the left or the right of the molecule? as in, how do we know that the phenol end was the tyr one? :s


It is always the case. The left will be the first amino acid of the protein chain :smile:
Reply 71
Original post by abzy1234
It is always the case. The left will be the first amino acid of the protein chain :smile:


hey! are you ready for this exam?! I still have rates of reaction theory to go over :s-smilie:
i have a quick question:- is this definition correct for bidentate ligands
The ligand can form 2 bonds to the central metal ion by using lone pairs of electrons from two of its atoms.

I thought the june 2012 paper was quite difficult! What are you views? and also is it true that january papers are much easier than june ones?
Reply 72
Original post by sharon800
hey! are you ready for this exam?! I still have rates of reaction theory to go over :s-smilie:
i have a quick question:- is this definition correct for bidentate ligands
The ligand can form 2 bonds to the central metal ion by using lone pairs of electrons from two of its atoms.

I thought the june 2012 paper was quite difficult! What are you views? and also is it true that january papers are much easier than june ones?


Hey! Yup I feel that I am ready. I've done tons of past papers, and I feel that I am getting used to the style of papers. I'm lucky that I did reaction kinetics as my A2 cswk, so that is pretty much sorted and in my head :tongue:

Yup your definition is correct. But if I was to be picky, the mark scheme (which is very specific) defines it as uses two lone pair of electrons to form dative covalent bonds with the metal. I always try and use the mark scheme definitions to be on the safe side :tongue:

I think it was an average paper to be honest. I think the more you practice on past papers from 2010, you will gradually get used to this format; where it seems a lot of synoptic elements are used. Remember, the chemistry is the same, don't be put off by how they ask you it.

And nope, it fluctuates and changes so much, that I wouldn't think Jan papers are easier. January 2011 was particularly challenging, whereas June 2011 had the highest grade boundaries as it was rather straightforward.

Learn your content, be confident and tackle them past papers. Good luck :biggrin:
Reply 73
Hey everyone,

I've done every single past paper for Chemistry of Materials from 2005 - 2012. I've done the ones from the current specification 3 - 4 times each. I've basically memorised every single mark scheme. I've gone over all of the content and I don't feel there is a single thing I don't know.

I'm not sure what to revise anymore. Any tips?
Reply 74
Original post by thelion0
Hey everyone,

I've done every single past paper for Chemistry of Materials from 2005 - 2012. I've done the ones from the current specification 3 - 4 times each. I've basically memorised every single mark scheme. I've gone over all of the content and I don't feel there is a single thing I don't know.

I'm not sure what to revise anymore. Any tips?


Have you done the Chemical Ideas Textbook questions? They are really good.

And keep on going through your content, covering up your notes and writing down what you can remember.

Do some extra reading as well around some of the topics; that always helps :smile:
Reply 75
Yep you do. As long as you do 10-12 hours a day of solid Chemistry. I'm only saying this because I don't know what stage your at.

Past papers are very important do every single one!
Reply 76
Original post by abzy1234
Have you done the Chemical Ideas Textbook questions? They are really good.

And keep on going through your content, covering up your notes and writing down what you can remember.

Do some extra reading as well around some of the topics; that always helps :smile:


Thank you for the tips! I'll be sure to use them :smile:
Can someone please explain water absorption to me?
Questions keep coming up, and its not in the textbooks anywhere?Is it something to do with hydrogen bonding?
Thanks
Reply 78
Original post by jackerharder
Can someone please explain water absorption to me?
Questions keep coming up, and its not in the textbooks anywhere?Is it something to do with hydrogen bonding?
Thanks


a polymer can only absorb water if it can form hydrogen bonding with the water molecules. The lone of electron on the atom of the polymer forms hydrogen bonding with water. for example, when nylon absorbs water, it is because it can form hydrogen bonding with it and also this affects its tg. Water molecules allow chains to slide past each other because they act as " plasticiser" if you know what i mean. so tg is lowered. the tg is therefore is below temperature, and hence becomes flexible.
Reply 79
my school has only had us do papers from 2009 upwards, where can i get the stuff from before that?