Question

What is the mass of Cu metal produced at the cathode during the passage of 5 ampere current through CuSO₄ solution for 6000 seconds? Molar mass of Cu is 63.5 g mol⁻¹.

Answer 1

Stoichiometry for the formation of Cu is

\[\ce{Cu^{2+}_{ (aq)} + 2e- -> Cu_{(s)}}\]

Hence,

Mole ratio = `(1  "mol")/(2  "mol e"^-)`

= `1/2`

Mass of Cu formed,

W = `("I"("A") xx "t"("s"))/(96500 ("C"// "mol e"^-)) xx "Mole ratio" xx "Molar mass of Cu"`

= `(5 xx 6000)/96500 xx 1/2 xx 63.5`

= `9525/965`

= 9.8704 g

∴ Mass of Cu metal produced at cathode is 9.8704 g.