Question

Sometimes water can be oxidized when electrolysis takes place in aqueous solutions. What are the reactions, SRPs and where do they occur? When would water be oxidized or reduced?

Answer 1

Water can be oxidized or reduced during electrolysis, where oxidation occurs at the anode producing oxygen gas and hydrogen ions, and reduction at the cathode produces hydrogen gas and hydroxide ions. SRPs determine whether water or another species in the solution undergoes redox.

Step-by-step explanation:

During electrolysis of aqueous solutions, water can either be oxidized or reduced, dependent on the substances present in the solution and their electrode potentials. Water is oxidized typically at the anode to produce oxygen gas (O2) and hydrogen ions (H+), while at the cathode, it is reduced to hydrogen gas (H2) and hydroxide ions (OH-). The tendency for water to undergo oxidation or reduction is determined by the relative standard reduction potentials (SRPs) of the other species in the solution.

For example, metals that do not react with water to produce hydrogen gas can be produced by the electrolytic reduction of an aqueous solution of the metal cation. Conversely, nonmetallic elements that do not easily oxidize water to oxygen can be obtained by electrolytic oxidation of an appropriate anion present in the solution. This understanding is crucial for predicting the outcomes of redox reactions in aqueous solutions.