Corrosion of an iron pipe can be prevented by connecting it to a magnesium bar buried in the ground. The magnesium corrodes in preference to the iron.
If the average current flowing between the two metals is 2.0 × 10^–6 A, the amount of magnesium metal, in mol, reacting each second, would be
A. 1.0 × 10^–11
B. 2.1 × 10^–11
C. 4.1 × 10^–11
D. 0.19
Solution
Which one of the following describes the polarity of the anodes in electrolytic and galvanic cells?

A. electrolytic cells=positive, galvanic cells=positive
B. electrolytic cells=positive, galvanic cells=negative
C.electrolytic cells=negative, galvanic cells=negative
D. electrolytic cells=negative, galvanic cells=positive
Solution
An aqueous solution containing a mixture of 1.0 M KI and 1.0 M CaBr₂ was electrolysed using unreactive electrodes.
Which one of the following reactions is most likely to occur at the anode?
A. 2H₂O(l) + 2e– → H₂(g) + 2OH^–(aq)
B. 2Br^–(aq) → Br₂(aq) + 2e–
C. Ca²⁺(aq) + 2e– → Ca(s)
D. 2I^–(aq) → I₂(aq) + 2e–
Solution
Lithium metal is manufactured by electrolysis of lithium salts.
Which of the following would be the best choice for the electrolyte and the anode in a commercial cell?
electrolyte anode
A. LiCl solution iron rod
B. molten LiCl iron rod
C. LiCl solution carbon rod
D. molten LiCl carbon rod
Solution

A classroom experiment was set up to simulate the industrial extraction of zinc metal from an aqueous solution of zinc ions by electrolysis. In this experiment 150 mL of 1.00 M ZnSO₄ solution was electrolysed at 25°C
using inert carbon electrodes.
Write a half-equation for the oxidation reaction.
Solution

A mass of 0.900 g of zinc is produced in 30.0 minutes.
Calculate the electric current, in A, supplied to the cell during the electrolysis. Express your answer to an appropriate number of significant figures.

Solution