Edexcel Unit 5:Transition Metals and Organic Chemistry 6CH05 (15th June 2015)

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Reply 40

nida234

Original post by Ripper Phoenix

C gives an rfm of 88 and the molecular ion peak is 86? thats impossible

I Know. I thought it's D. But it's not. It's given C in the MS. :mad:

Reply 41

nida234

Original post by ripper phoenix

c gives an rfm of 88 and the molecular ion peak is 86? Thats impossible

okay my badd!!!!
I saw the wrong marking scheme. :colondollar:

Reply 42

Ripper Phoenix

Original post by nida234

okay my badd!!!!
I saw the wrong marking scheme. :colondollar:

lol no problem .. what is the correct answer anyway?

Reply 43

cerlohee

Original post by aersh8

Amines are ligands - that's all you need to know for this one :smile:

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Ah, okay. Was just a bit confused as everything I've learnt so far to do with copper is blue!
Chem teacher says the colour's irrelevant though, just that its a ligand so agreeing with you :smile:

Reply 44

nida234

Original post by Ripper Phoenix

lol no problem .. what is the correct answer anyway?

It's D.

Reply 45

aersh8

Original post by cerlohee

Ah, okay. Was just a bit confused as everything I've learnt so far to do with copper is blue!
Chem teacher says the colour's irrelevant though, just that its a ligand so agreeing with you :smile:

If you carry out a ligand exchange reaction
(Cu(H2O)6)2+ +4Cl- <-> (Cu(Cl)4)2- + 6H2O
You get a green colour too since the aqua complex is blue while the chloro complex is yellow (so since it's reversible you get a mixture of the two colours giving green).
Cu+ is usually white (due to full 3d orbitals so no d-d electron transitions possible), while Cu2O (s) is red and CuO (s) is black.

So please don't think that all copper compounds are blue :smile:

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Reply 46

Nid03

Please help me out with this bull crap.
When a solution containing 0.10 mol of chromium(III) chloride, CrCl3.6H2O, is treatedwith excess silver nitrate solution, 0.20 mol of silver chloride, AgCl, is immediatelyprecipitated. The formula of the complex ion in the solution is
A [Cr(OH)6]3–
B [Cr(H2O)6]3+
C [CrCl(H2O)5]2+
D [CrCl2(H2O)4]

Answer's C. Could someone explain it to me please.

Reply 47

aersh8

Original post by Nid03

You know it's a chloro complex (thanks to the excess of Cl-) so A and B are eliminated. For D, the oxidation number of chromium is +2 so it's wrong (since you're told it's +3). So you're left with C, which is both chloro and has the correct oxidation state of +3.

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Reply 48

Nid03

Original post by aersh8

THANKS

I got it.

Reply 49

cerlohee

I have another questions whoops!

Which of the following reagents would enable you to separate iron(III) hydroxide from a
mixture of iron(III) hydroxide and copper(II) hydroxide?
A Dilute hydrochloric acid
B Aqueous ammonia
C Dilute nitric acid
D Sodium hydroxide solution

Thanks!

Reply 50

frozo123

Original post by cerlohee

I think it's B because Fe3+ doesn't dissolve in aqueous ammonia where as Copper would :smile:

Reply 51

cerlohee

Original post by frozo123

I think it's B because Fe3+ doesn't dissolve in aqueous ammonia where as Copper would :smile:

Ah yeah that makes sense!! Thanks :smile:

Reply 52

frozo123

Original post by cerlohee

Ah yeah that makes sense!! Thanks :smile:

Don't take my word for it though could be wrong!

Reply 53

cerlohee

Original post by frozo123

Don't take my word for it though could be wrong!

Haha well it's true so I don't see why it would be :biggrin:

Do you, or anyone for that matter, know why the others are wrong? Or is that no necessary lol

Reply 54

frozo123

Original post by cerlohee

Haha well it's true so I don't see why it would be :biggrin:

Do you, or anyone for that matter, know why the others are wrong? Or is that no necessary lol

erm well for nitric and hydrochloric acid
you're reacting an acid with a base, they're both bases
you'll form salt + water for both of them which are both aqueous so that won't work
with sodium hydroxide, they're both insoluble with excess sodium hydroxide
the only hydroxides that are amphoteric in the first row of the d block elements are Zinc and Chromium I believe..

Any other questions feel free to ask cus it helps with my revision too :smile:

Reply 55

aersh8

Original post by cerlohee

Both for a precipitate with ammonia but the copper one dissolves in excess so I'd go with B

Edit: woops just saw it was answered already :P

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Reply 56

cerlohee

Original post by frozo123

Woo thanks! I probably will have a lot i'm dreadful at unit 5 hahah

Reply 57

frozo123

Original post by cerlohee

Woo thanks! I probably will have a lot i'm dreadful at unit 5 hahah

I'm awful too haha

Reply 58

Juli23

Hey guys

was wondering if you could let me know how many chem papers you've completed by now just so I know I'm on track

These papers take me hours to cover once I've completed them. This involved marking, the markscheme, examiner reports and writing notes.

is this just me or the same for everyone?

Thank you