The Student Room Group

Chemistry - Redox II

The standard electrode potentials of two half reactions are shown below.
½Cl2 + e− --> Cl− E = +1.36 V
Co3+ + e− --> Co2+ E = +1.82 V
Which of the following processes is thermodynamically favourable?
The reaction of
A) Co2+ with Cl2 to form Cl−
B) Co2+ with Cl− to form Cl2
C) Co3+ with Cl2 to form Cl−
D) Co3+ with Cl– to form Cl2

Help pleaseeee!!!!
Reply 1
I'm not sure about it being thermodynamically favoured, but just from an electrochemistry point of view I can help you answer.

If a reaction is feasible the Ecell is greater than 0. Do you know how to work out the emf for a reaction as this may help?
Reply 2
@IJaguar

Thanks for replying

Yeah above 0 is feasilbe.
Emf would be reduced - oxidised which means emf= 1.82-1.36= 0.46V

But I'm not sure how this would help figure out the answer

The answer is D btw
(edited 2 years ago)
Reply 3
Original post by Piriyanka22
@IJaguar

Thanks for replying

Yeah above 0 is feasilbe.
Emf would be reduced - oxidised which means emf= 1.82-1.36= 0.46V

But I'm not sure how this would help figure out the answer

The answer is D btw


If the reduced equation is the bottom one, the oxidised equation is the top one.

So the two equations would be

Co3+ + e- -> Co2+ and
Cl- - > 1/2Cl2 + e-

Can you work out what's reacting from that?
Reply 4
No I am not sure

Quick Reply

Latest