[Abrar_Higuain]

um reallly scared with the synoptic questions...specially regarding Organic synthesis routes.....i seem to forget them always.....any advise what i myt do?????

[Chaofan88]

quick question guys, [Cr(H2O)6]3+ is purple right? Providing there are only water ligands swimming around.

[marcus94]

(Original post by Abrar_Higuain)
um reallly scared with the synoptic questions...specially regarding Organic synthesis routes.....i seem to forget them always.....any advise what i myt do?????

Do a massive flow chart for all the reactions you have learnt over the last two years.

(Original post by Chaofan88)
quick question guys, [Cr(H2O)6]3+ is purple right? Providing there are only water ligands swimming around.

I've remembered it as green but i remember someone saying they thought it was purple/green colour and some said purple. im guessing they will accept all on a mark scheme though. Best thing to do is go check on a ms somewhere - im sure there has been a question on it previously

[arnab]

(Original post by giraffegiraffe)
no our teacher said we just need to know the electrophile is SO3 and the product is benezenesulfonic acid, but we don't need the mechanism

(Original post by King_Arthur)
i don't think need to but it's not that different from any other E+ substitution
http://www.chemguide.co.uk/mechanism...phonation.html

Thank you both!

[arnab]

Guys what do we need to know about application of aromatic compounds?

[NutterFrutter]

(Original post by arnab)
Guys what do we need to know about application of aromatic compounds?

Can you expand on this. What do you mean by "application"?

[NutterFrutter]

(Original post by Chaofan88)
quick question guys, [Cr(H2O)6]3+ is purple right? Providing there are only water ligands swimming around.

It's actually green. Technically it's blue-violet but because of negative ions in the solution (e.g. Cl-) they can replace one of the water ligands and so it appears green.

You'd never only get water ligands but yes if that was the case then it would be a purple (violet) colour. They'd probably accept green/purple/violet/blue-violet/ruby

[Backflip]

(Original post by arnab)
Guys i have a big question > you see complex ions with 4co-ordination number, WHY do they form two isomers (tetrahedral and square planner)?

There are no hard and fast rules for whether it will form a tetrahedral or square planar complex. However, square planar complexes form almost exclusively with metal ions with the d^8 configuration.
For example; Cisplatin Pt(NH3)2(Cl-)2 forms a square planer complex which is one to be aware of. Another example is [Ni(CN-)4]2-.

[Backflip]

(Original post by arnab)
Guys what do we need to know about application of aromatic compounds?

Vague... but dyes are a major use. Pharmaceuticals is a general point. Sulphonation of aromatic rings is an important reaction in the manufacture of many detergents/surfactants.

[Jukeboxing]

(Original post by XiaoXiao1)
Cheers that's really helpful, only isn't Cr 3+ Green?

Like i said, some may not agree with the colours but my teacher did all the reactions in front of the class, so thats where I got the colours from.

(Original post by arnab)
are you sure this is right?

For Cr with OH-

Blue-purple solution >>>>>>> Muddy green precipitate

[Cr(H2O)6]3+ + 3NH3 >>>>>>>> [Cr(H2O)3(OH)3] + 3NH4+

I thought the formula for the purple solution was [Cr(Nh3)6]3+?

It is correct, [Cr(NH3)6]3+ is what you get when dissolve the Cr3+ in excess NH3

[Alexlol28]

(Original post by shahofiran)
Also, why is Mn(II) more stable than Mn(III)?

Mn(II) has an extra electron, it is more charged dense, hence more stable

[nmudz_009]

(Original post by marcus94)
basically if there is only one type of ligand its going to be tetrahedral and if there are two different types of ligands its going to be square planar. thats how ive learnt it

Isn't (Ni(cl)4) ^2- square planer?

[nmudz_009]

(Original post by giraffegiraffe)
I get confused on this too. Our teacher has told us that if the coordination number is 4, assume its Tetrahedral, unless the compound is Pt(NH3)2Cl2 which is the one we have to know as being square planar (and also (NiCl4)2-)

Hey Are those two the only square planar molecules we need to know about?

[nmudz_009]

(Original post by Chaofan88)
quick question guys, [Cr(H2O)6]3+ is purple right? Providing there are only water ligands swimming around.

erm my teacher actually said green violet, but colours are subjective I guess

[giraffegiraffe]

(Original post by nmudz_009)
Hey Are those two the only square planar molecules we need to know about?

Yess i think the main one to be aware of is the Pt.... one

[EffKayy]

(Original post by Jukeboxing)
x

Wanna scriblink in like an hour? :P

[bsblitter]

Can someone explain to me when we have to use the platinum electrode in the half cells?

thanks

[11billi11]

Can some one please help on transitional metal colours.. Mn2+ , Ni2+, Cr2+, Co2+.. I am using different books to revise some are really old and have completely confused me as they contain conflicting info regarding colours of these compounds e.g. with excess NH3

[nmudz_009]

(Original post by giraffegiraffe)
Yess i think the main one to be aware of is the Pt.... one

Thanks

[nmudz_009]

Whats the colour of the solution made when hexa aqua chromium(iii) is dissolved in excess ammonia? My book says actually says yellow solution, but in my class notes ive got it written as purple can anyone confirm