Question

A constant current of 114.5 A is passed through an electrolytic cell having an impure copper anode, a pure copper cathode, and an aqueous CuSO4 electrolyte.

How many kilograms of copper are refined by transfer from the anode to the cathode in a 22.0 h period?

Answer 1

Solution :-

Lets first calculate the charge

charge = current * time in second

charge = 114.5 A * (22.0 h *3600 s/1 h) = 9068400 C

now lets calculate the moles of electrons

1 mole e- = 96485 C

therefore

9068400 C * 1 mol e- / 96485 C = 94 mol e-

1 mol Cu^2+ needs 2 mole electrons

94 mol e- * 1 mol Cu / 2 mol e- = 47 mol Cu

now lets convert moles of Cu to its mass

mass of Cu = moles * molar mass

                    = 47 mol Cu * 63.546 g per mol

                   = 2987 g Cu

now lets convert gram to kg

2987g * 1 kg / 1000 g = 2.987 kg Cu

so mass of Cu that can be produced = 2.987 kg