Question

At 25°C, the standard e.m.f. of a cell having reaction involving two electron change is found to be 0.295 V. The equilibrium constant of the reaction is ______.

Options

• 29.5 × 10⁻²

• 10

• 1 × 10¹⁰

• 29.5 × 10¹⁰

Answer 1

At 25°C, the standard e.m.f. of a cell having reaction involving two electron change is found to be 0.295 V. The equilibrium constant of the reaction is 1 × 10¹⁰.

Explanation:

Given: \[\ce{E{^{\circ}_{cell}}}\] = 0.295 V

n = 2 electrons

The relation between standard cell potential and equilibrium constant K is:

\[\ce{E{^{\circ}_{cell}} = \frac{0.0591}{n} log K}\]

\[\ce{0.295 = \frac{0.0591}{2} log K}\]

\[\ce{log K = \frac{0.295 × 2}{0.0591}}\]

log K ≈ 10

K = 10¹⁰

So, the equilibrium constant is 1 × 10¹⁰.