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).
Al3++3e−→Al
The number of moles of Al = 13 g27 g/mol=0.48 mol
1 mole of Al is produced by 3 moles of electrons.
0.48 mole of Al is produced by 3×0.48=1.44 moles of electrons. This corresponds to 1.44 faradays of electricity.
Note: 1 faraday of electricity corresponds to 1 mole of electrons.