Question

How many Faradays of electricity are required to produce 13 gram of aluminium from aluminium chloride solution ? (Given : Molar mass of Al = 27.0 gram mol^–1)

Answer 1

AlCl₃ → Al³⁺ + 3Cl^– 

 Al³⁺ + 3e^– → Al

1 mole of Al requires passage of 3 mole of electrons. Charge on 3 mole of e^– is 3 Faraday.

Moles of Al produced = Mass of Al/Molar mass of Al

= 13/27 = 0 .48 Moles

3F of electricity produces 1 mole of Al.

:.  Number of Faradays of electricity required to produce 0.48 moles of Al

= 0.48 x 3

= 1.44 Faraday.