When hypochlorite ions act as an oxidizing agent, hydroxide ions are formed. What will this do to iron (II) or to iron (III) ions?
Both Fe(OH)2 and Fe(OH)3 are insoluble in an aqueous solution.
When hypochlorite ions (ClO-) act as an oxidizing agent, they will react with water to form hypochlorous acid (HOCl) and hydroxide ions (OH-). The hydroxide ions can then react with iron (II) or iron (III) ions to form insoluble hydroxide compounds.
In the case of iron (II) ions (Fe2+), the hydroxide ions will react with them to form iron (II) hydroxide (Fe(OH)2). Iron (II) hydroxide is insoluble in aqueous solutions, which means it will precipitate out of the solution as a solid. The equation for this reaction is:
Fe2+ + 2OH- -> Fe(OH)2
Similarly, in the case of iron (III) ions (Fe3+), the hydroxide ions will react with them to form iron (III) hydroxide (Fe(OH)3). Iron (III) hydroxide is also insoluble in aqueous solutions and will precipitate out. The equation for this reaction is:
Fe3+ + 3OH- -> Fe(OH)3
In both cases, the formation of insoluble hydroxide compounds will cause the iron (II) or iron (III) ions to be removed from the solution as solid precipitates.