Question

In basic solution, hypochlorite ions, oxidize chromite ions, to chromate ions, and are reduced to chloride ions. Write the balanced net ionic equation for this reaction.

Answer 1

We are given the formulas for two reactants and two products; we write as much of the equations as possible. The reaction occurs in basic solution; we can add OH^- and H₂O as needed. We construct and balance the appropriate half-reactions, equalize the electron transfer add the half-reactions, and eliminate common terms.

CrO₂^- + ClO^- -> CrO₄^2- + Cl^-

CrO₂^- -> CrO₄^2- (ox. half-rxn)

CrO₂^- + 4OH^- -> CrO₄^2- + 2H₂O

CrO₂^- + 4OH^- -> CrO₄^2- + 2H₂O + 3e^- (balanced ox. half-rxn)

ClO^- -> Cl^- (red. half-rnx)

ClO^- + H₂O -> Cl^- + 2OH^-

ClO^- + H₂O + 2e^- -> Cl^- + 2OH^- (balanced red. half-rnx)