An aqueous solution of silver nitrate ( AgNO ₃ ) is electrolysed using a steady current of 0.965 A. If 1.62 g of silver is deposited at the cathode, the time (in minutes) for which the current was passed is : (Given : Molar mass of Ag = 108 g mol ⁻¹ ; 1 F = 96500 C mol ⁻¹ )

Step-by-step solution

The reduction reaction at the cathode is Ag ⁺ + e ⁻ Ag . Here, the number of electrons involved, n = 1 . From Faraday's first law of electrolysis, the mass of silver deposited is: m = M I t n F Rearranging for time t (in seconds): t = m n F M I Substituting the given values: t = 1.62 1 96500 108 0.965 = 156330 104.22 = 1500 s Converting the time into minutes: t = 1500 60 = 25 minutes Answer: 25