Chapter 20, Problem 10QAP

Zinc is produced by electrolytic refining. The electrolytic process, which is similar to that for copper, can be represented by the two half-reactions
   $\begin{array}{l}\text{Zn}\left(\text{impure},s\right)\to Z{n}^{2+}+2e^{-}\\ Z{n}^{2+}+2e^{-}\to \text{Zn}\left(\text{pure},s\right)\end{array}$
For this process, a voltage of 3.0 V is used. How many kilowatt hours are needed to produce one metric ton of pure zinc?