Question

Calculate the standard cell potentials of galvanic cells in which the following reactions take place:

(i) 2Cr(s) + 3Cd²⁺(aq) → 2Cr³⁺(aq) + 3Cd

(ii) Fe²⁺(aq) + Ag⁺(aq) → Fe³⁺(aq) + Ag(s)

Calculate the Δ_rG^θ and equilibrium constant of the reactions.

Answer 1

(i)

The galvanic cell of the given reaction is depicted as:

Now, the standard cell potential is

In the given equation,

n = 6

F = 96487 C mol⁻¹

= +0.34 V

Then, = −6 × 96487 C mol⁻¹ × 0.34 V

= −196833.48 CV mol⁻¹

= −196833.48 J mol⁻¹

= −196.83 kJ mol⁻¹

Again,

= −RT ln K

= 34.496

K = antilog (34.496)

= 3.13 × 10³⁴

(ii)

The galvanic cell of the given reaction is depicted as:

Now, the standard cell potential is

Here, n = 1.

Then,

= −1 × 96487 C mol⁻¹ × 0.03 V

= −2894.61 J mol⁻¹

= −2.89 kJ mol⁻¹

Again,

= 0.5073

K = antilog (0.5073)

= 3.2 (approximately)