Question

If the half-reaction: Fe3+ + e- = Fe2+ were chosen as the standard reduction potential table reference instead of: 2H+ + 2e- = H2, what would the Eo value for Zn2+ reduction be?

Answer 1

`E^(0)` for
`Zn^(2+)\mid Zn` system would be -1.53 V

Step-by-step explanation:

Determination of standard reduction potential of any system is done by placing the system in cathode and a reference half cell in anode and then evaluate the cell potential. The cell potential is the standard reduction potential of the system.

So
`E_(cell)^(0)=E_(system)^(0)-E_(reference)^(0)`

As
`E_{H^(+)\mid H_(2)}^(0)` is equal to 0 therefore cell potential is equal to reduction potential of any system by taking hydrogen electrode as a reference.

`E_(Zn^(2+)\mid Zn)^(0)` equal to -0.76 V with respect to hydrogen

`E_(Fe^(3+)\mid Fe^(2+))^(0)` equal to 0.77 V with respect to hydrogen

Therefore standard reduction potential of
`Zn^(2+)\mid Zn` system when
`Fe^(3+)\mid Fe^(2+)` system is taken as reference is-

`E_(cell)^(0)=E_(Zn^(2+)\mid Zn)^(0)-E_(Fe^(3+)\mid Fe^(2+))^(0)`

= -0.76 V - 0.77 V

= -1.53 V