Question

consider the reaction: 2ag+ + cd 2ag + cd2+ the standard electrode potentials for ag+ /ag and cd2+/cd couples are 0.80 volt and -0.40 volt. what is the standard potential e for this reaction

Answer 1

whenever we have such question we should write the cathode and anode reaction.

Let's take the reaction

2Ag+  + Cd(s)  →  2Ag(s)   + Cd2+

Ag+ is getting reduced to solid Ag with means reduction is taking place and it will take place in Cathode

Cd is getting oxidised to Cd2+, which means it will take place at Anode

so we can write '

Anode reaction   Cd2+  ---> Cd + 2e-

Cathode reaction : Ag+ + e-    ----->  Ag

We have Reduction potential of E Cd2+/Cd = -0.40

and Reduction Potential of E Ag+/Ag = 0.80

The Cell potential is calculated as

$E^o _{cell} = E^o_{red, cathode} - E^o_{red, anode}$

So Answer is

$E^o_{cell}=0.80-(-0.40)$

= 1.20 V