Question

Eº for Cr3+ + 3e-> Cr and Cr3+ + e- >Cr2+
are -0.74V and -0.40V respectively. Eº for
the reaction is :-
Cr2+ + 2e -> Cr​

Answer 1

Answer:

Eø Cr3+ / Cr = - 0.74 V

Eø Cd2+ / Cd = - 0.40 V

The galvanic cell of the given reaction is depicted as:

Now, the standard cell potential is

Eø = EøR - EøL

= -0.40 - (-0.74)

= + 0.34 V

ΔrGø = -nFEøcell

In the given equation,

n = 6

F = 96487 C mol - 1

Eøcell = +0.34 V

Then, ΔrGø = - 6 × 96487 C mol - 1 × 0.34 V

= - 196833.48 CV mol - 1

= - 196833.48 J mol - 1

= - 196.83 kJ mol - 1

Again,

ΔrGø = - RT ln K

= 34.496

K = antilog (34.496)

= 3.13 × 1034