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Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed)

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Original post by lordmackery
I did a question:

The cell represented below was set up under standard conditions

Pt| Fe2+ , Fe3+ || Tl3+, Tl+ |Pt Cell e.m.f. = +0.48V

Use these relevant half equations to write an equation for the spontaneous cell reaction.

Fe3+ + e- -> Fe2+
Tl3+ + 2e- -> Tl+


I wrote:

Tl3+ + 2Fe2+ -> Tl+ + 2Fe3+

is that correct?

Apart from what James said, your method is correct (reversing the oxidized equation) and multiplication to get the same number of electrons.
For the Tl3+ + 2e- -> Tl+
I think it should be Tl3+ + 3e- -> Tl+
Reply 401
Avatar for jojo1995
jojo1995
2
Original post by David Tennant
Hey Jojo,

I think this is right! You see, it's reduction of the nitrobenzene to the phenylamine.

C6H5NO2 + 6H+ (in the presence of Sn and HCl)——————→ C6H5NH2 + 2H2O


Thanks David, yeah that is right :smile:

I just dk if we need to know like the whole equation. I came up with one but idk if its correct :frown: could you look at it pls ? Below


C6H5NO2 + 3Sn + 6HCl ~~> C6H5NH2 + 2H2O + 3SnCl2
Original post by jojo1995
Thanks David, yeah that is right :smile:

I just dk if we need to know like the whole equation. I came up with one but idk if its correct :frown: could you look at it pls ? Below


C6H5NO2 + 3Sn + 6HCl ~~> C6H5NH2 + 2H2O + 3SnCl2

My PowerPoint doesn't have the full equation, just a picture of an arrow going to the nitro benzene and the phenylalamine...
George Facer just gives it as what I had above,( by the way when I said H+ I meant 6[H] (as in the reducing agent)).

As SN and HCl are catalysts, I don't think we need to include them in the equation, but I'm not 100% sure.
Reply 403
Avatar for jojo1995
jojo1995
2
Original post by David Tennant
My PowerPoint doesn't have the full equation, just a picture of an arrow going to the nitro benzene and the phenylalamine...
George Facer just gives it as what I had above,( by the way when I said H+ I meant 6[H] (as in the reducing agent)).

As SN and HCl are catalysts, I don't think we need to include them in the equation, but I'm not 100% sure.


Yeah I think you are right, thanks so much :biggrin: !


How you finding chem 5 - have started amino acids yet ? It looks hard :redface:
(edited 11 years ago)
Original post by David Tennant
My PowerPoint doesn't have the full equation, just a picture of an arrow going to the nitro benzene and the phenylalamine...
George Facer just gives it as what I had above,( by the way when I said H+ I meant 6[H] (as in the reducing agent)).

As SN and HCl are catalysts, I don't think we need to include them in the equation, but I'm not 100% sure.


The spec is extremely vague when it comes to the word equations we have to memorise.

I would defo remember the equation, but is HCL also a catalyst??

After all, it isn't regenerated :s-smilie:
Original post by James A
Your half equation for TI3+ + 2e- ---> TI+ is wrong.

Your atoms don't balance right here and hence the charges don't balance.


Sorry TI was meant to be titanium.
the first one with 3+ charge the other with 1+
Original post by lordmackery
Sorry TI was meant to be titanium.
the first one with 3+ charge the other with 1+


Makes sense now :yep:
Reply 407
Avatar for senz72
senz72
19
Really guys?
Really?
Guys, what would you name this?
I went for 2-amino-3-hydroxy-3-phenylpropane
but it took me a number of tries, so I have no idea what takes the end of the name.
A.png
How's revision going?
Original post by jojo1995
Yeah I think you are right, thanks so much :biggrin: !


How you finding chem 5 - have started amino acids yet ? It looks hard :redface:

We've just got onto the nitrogen chemistry part, I'm looking forward to the amino acids because I want to be able to see them from another perspective (as oppose to Biologically), but there isn't too much on amino acids?
Chem 5, with enough revision and past papers shouldn't be to difficult...I still can't get my head over the electrochemical stuff though and with all the reactions and mechanisms, it's beginning to feel like unit 2 all over again!

Original post by James A
The spec is extremely vague when it comes to the word equations we have to memorise.

I would defo remember the equation, but is HCL also a catalyst??

After all, it isn't regenerated :s-smilie:

Yeah your right, the only catalyst is the tin!
Original post by Mollymod
Guys, what would you name this?
I went for 2-amino-3-hydroxy-3-phenylpropane
but it took me a number of tries, so I have no idea what takes the end of the name.
A.png
How's revision going?


I'm making the asumption that we name from the phenyl group which has priority. I'm not 100% sure, but the IUPAC book will tell us.

2-amino-1-hydroxy-phenylpropane
Original post by James A
I'm making the asumption that we name from the phenyl group which has priority. I'm not 100% sure, but the IUPAC book will tell us.

2-amino-1-hydroxy-phenylpropane

That sounds about right because it adds up to the lowest total, but why wouldn't it be 2-amino-1-hydroxy-1-phenylpropane?
as you name where the phenyl group is on the alkyl chain?
Original post by Mollymod
That sounds about right because it adds up to the lowest total, but why wouldn't it be 2-amino-1-hydroxy-1-phenylpropane?
as you name where the phenyl group is on the alkyl chain?


Because we made the assumption that the phenyl group takes priority over the others in the alkyl chain when it comes to numbering the carbon atoms, so there would be no need to put a 1 (although it is perfectly right if you chose to do so) because of the assumption!
Woops, ignore that last post
Here it is:

(1S,2R)-2-amino-1-phenylpropan-1-ol
(edited 11 years ago)
Original post by David Tennant
Woops, ignore that last post
Here it is:

(1S,2R)-2-amino-1-phenylpropan-1-ol


The R and S, are you talking about rectus and sinister enantiomers? :redface:
Original post by David Tennant
Woops, ignore that last post
Here it is:

(1S,2R)-2-amino-1-phenylpropan-1-ol


:beard:

Mark schemes are lenient when it comes to naming compounds which is dead handy :borat:
Original post by Mollymod
The R and S, are you talking about rectus and sinister enantiomers? :redface:

Not sure about rectus and sinister enantiomers...Wolfram alpha did though :lolwut:!
Hello all, does anyone have the answers to the Unit 4 review questions from the Hodder book? I'm having trouble finding them.
Original post by 1234lime
Hello all, does anyone have the answers to the Unit 4 review questions from the Hodder book? I'm having trouble finding them.

The unit 5 ones are posted, I will look for unit 4 soon for you :biggrin:
aha, I like the poll...

hopefully I can make my way across the salt bridge and onto feeling electrophilic soon :biggrin:

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