Question

For the reduction of silver ions with copper metal, the standard cell potential was found to be +0.46 V at 25°C. The value of standard Gibbs energy, ΔG° will be ______. (F = 96500 C mol⁻¹)

Options

• −89.0 kJ

• −89.0 J

• −44.5 kJ

• −98.0 kJ

Answer 1

For the reduction of silver ions with copper metal, the standard cell potential was found to be +0.46 V at 25°C. The value of standard Gibbs energy, ΔG° will be −89.0 kJ.

Explanation:

Given: \[\ce{E^{\circ}_{cell}}\] = 0.46 V

n = 2 electrons (since \[\ce{Ag+ + e- -> Ag}\], and 2Ag⁺ react with Cu)

F = 96500 C mol⁻¹

The standard Gibbs free-energy change is calculated using the relation:

\[\ce{\Delta G{^{\circ}} = -nFE{^{\circ}_{cell}}}\]

= −2 × 96500 × 0.46

= −88780 J

Convert to kJ:

ΔG° = −88.8 kJ mol⁻¹

≈ −89.0 kJ