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Edexcel Chemistry Unit 5 June 19 2012

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Reply 180
Original post by Jukeboxing
I'm not sure why, but i think it has something to do with the arrangment of orbitals.

Maybe someone else may know why.


is it to do with something about the amount of free orbitals because Zn2+ would become [Ar] 3d10 4s0. meaning that there would be only 4 orbitals that can be filled by the dative covalent bonds ie/ the 4s0 and the 4p0 which allows 4 dative covalent bonds?? (im guessing - seems like the only logical answer)
Reply 181
Original post by keerthi3
Can someone please reply to this?

I'm using George Facer book to revise and I'm finding loads of extra information that is not in our specification Do we need the chemical reactions of phenylamine?


The main reaction of phenylamine that you should know is with Hcl and Nano2 to form benzene diazonium ion(chloride)

Also there are usual stuff like adding bromine - which is just the same as if you were adding bromine to phenol

then it goes through the same reactions as just normal aliphatic amine ( because dont forget there is reactions with the ring as the main constituent and then the ring as a side group)

so:

amine + acid chloride => n-sub amide

amine + acid => salt

amine + water => amineh+ + oh-

thats all i can think of that i know
Reply 182
Original post by keerthi3
Can someone please reply to this?

I'm using George Facer book to revise and I'm finding loads of extra information that is not in our specification Do we need the chemical reactions of phenylamine?


I think you do.
From the revision book I'm using you need to know:
Its preparation and physical properties
Reactions of the NH2 group as a base
Reactions of the NH2 group with ethanoyl chloride
Reactions of the NH2 group with Copper (II) ions
Reactions of the NH2 group with Nitrous Acid
The ring is activated the same way it is for phenol
Reply 183
Original post by marcus94
The main reaction of phenylamine that you should know is with Hcl and Nano2 to form benzene diazonium ion(chloride)

Also there are usual stuff like adding bromine - which is just the same as if you were adding bromine to phenol

then it goes through the same reactions as just normal aliphatic amine ( because dont forget there is reactions with the ring as the main constituent and then the ring as a side group)

so:

amine + acid chloride => n-sub amide

amine + acid => salt

amine + water => amineh+ + oh-

thats all i can think of that i know


yeh marcus is right but mostly you have to know about the diazonium salt manufacture tbh (sodium nitrate and HCL making the HNO2 and HCL) They like these questions because there is alot to ask about as you have to keep it below 10degrees etc... also how to make it from nitrated benzene! soo yeh :biggrin:
Reply 184
can anyone explain to me why NH3 is a weaker base than CH3NH2??? doesnt make sense to me
Reply 185
Original post by physics1
can anyone explain to me why NH3 is a weaker base than CH3NH2??? doesnt make sense to me


Amines are bases because they pick up hydrogen ions on the lone pair on the nitrogen atom. In methylamine, the attractiveness of the lone pair is increased because of the way it interacts with the electrons of the ch3. the alkyl group "pushes" away its electrons so the nitrogen will be a little bit more delta negative this means it can pick up hydrogen more easily
(edited 11 years ago)
Hey !!
Whens a complex ion square planar and tetrahedral ?
The book I am using says a coordination no. of 4 attaching to ligands and complete d-subshells is formed means tetrahedral and vice versa for square planar :s-smilie:. I am confused I thought transition metals have incomplete d subshells ?
Reply 187
Original post by physics1
yeh marcus is right but mostly you have to know about the diazonium salt manufacture tbh (sodium nitrate and HCL making the HNO2 and HCL) They like these questions because there is alot to ask about as you have to keep it below 10degrees etc... also how to make it from nitrated benzene! soo yeh :biggrin:


Oh, I know the reactions of phenol and amine so basically all I need to do is combine them right? I thought adding sodium nitrate and HCL to phenylamine gives you benzenediazonium chloride instead of 'HNO2 and HCL' :/ Ahh I'm soo confused :frown:
Reply 188
Original post by Sykikdoc1993
Hey !!
Whens a complex ion square planar and tetrahedral ?
The book I am using says a coordination no. of 4 attaching to ligands and complete d-subshells is formed means tetrahedral and vice versa for square planar :s-smilie:. I am confused I thought transition metals have incomplete d subshells ?


I remember my teacher saying that the reasoning behind it is beyond a level. As said in a couple of posts in the thread the only ones we should know as being square planar is [pt(nh3)2(cl2)] and [cu(cl)4]2- (Dont take my word for it)
Reply 189
What is the colour of [Fe(CN)6]3- ?
Reply 190
Original post by 11billi11
What is the colour of [Fe(CN)6]3- ?


I think its blue
Reply 191
Original post by keerthi3
Oh, I know the reactions of phenol and amine so basically all I need to do is combine them right? I thought adding sodium nitrate and HCL to phenylamine gives you benzenediazonium chloride instead of 'HNO2 and HCL' :/ Ahh I'm soo confused :frown:


no you may be thinking of phenol with benzenediazonium ion to make an azo dye.

Your right... Basically the reaction occurs in two stages this is because Hno2 is very unstable and needs to make in situ : Firstly you need to make the HnO2

Nano2 + Hcl => HnO2 + Nacl

the overall reaction is:

c6h5nh2 +hno2 + 2hcl -> c6h5n2cl + 2h2o
(edited 11 years ago)
Original post by marcus94
is it to do with something about the amount of free orbitals because Zn2+ would become [Ar] 3d10 4s0. meaning that there would be only 4 orbitals that can be filled by the dative covalent bonds ie/ the 4s0 and the 4p0 which allows 4 dative covalent bonds?? (im guessing - seems like the only logical answer)


Yes, thats what I was thinking. But then I tried using the same logic with Cu2+ but It didnt seem to work.
Reply 193
Could someone please tell me what isoelectric means?
Reply 194
Original post by keerthi3
I think its blue


It doesn't state the colour in the revision guide either :s-smilie:
Reply 195
Original post by marcus94
Amines are bases because they pick up hydrogen ions on the lone pair on the nitrogen atom. In methylamine, the attractiveness of the lone pair is increased because of the way it interacts with the electrons of the ch3. the alkyl group "pushes" away its electrons so the nitrogen will be a little bit more delta negative this means it can pick up hydrogen more easily


when does the point come when adding alkyl groups has more impeding affects to basic action? e.g CH3CH2CH2NH2 is weaker...
Reply 196
Original post by Jukeboxing
Yes, thats what I was thinking. But then I tried using the same logic with Cu2+ but It didnt seem to work.


yeh exactly =/ Are you sure those equations are right and its not [zn(nh3)6] ??
Reply 197
Original post by marcus94
yeh exactly =/ Are you sure those equations are right and its not [zn(nh3)6] ??


is this from the CGP revision guide by any chance?
Reply 198
Original post by physics1
when does the point come when adding alkyl groups has more impeding affects to basic action? e.g CH3CH2CH2NH2 is weaker...


it doesnt, they all have similar effect regardless of the number of alkyl group. Its only when it has a benzene ring when it gets weaker as the nitrogen interacts with the ring
Reply 199
Original post by physics1
is this from the CGP revision guide by any chance?


No, im looking at Jukeboxing's sheets with all of the reactions, to be honest im not that sure because it seems to be different depending on what book you read

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