Question

How can electrolysis be used to produce chlorine?

Answer 1

Chlorine can be manufactured by electrolysis of a sodium chloride solution (brine). The production of chlorine results in the co-products caustic soda (Sodium hydroxide, NaOH) and hydrogen gas (`H_2`). These two products, as well as chlorine itself, are highly reactive. Chlorine can also be produced by the electrolysis of a solution of potassium chloride, in which case the co-products are hydrogen and caustic potash (Potassium hydroxide). There are three industrial methods for the extraction of chlorine by electrolysis of chloride solutions, all proceeding according to the following equations:

Cathode: 2H + (aq) + 2 e− → H2 
Anode: 2 Cl− (aq) → Cl2 + 2 e−

Overall process: 2 NaCl (or KCl) + 2 `H_2`O → `Cl_2` + `H_2` +
2 NaOH (or KOH)