Question

For a particular redox reaction NO2– is oxidized to NO3– and Cu2 is reduced to Cu . Complete and balance the equation for this reaction in basic solution. Phases are optional.

Answer 1

While balancing O and H - atoms in basic medium follow the below steps

For each excess O - atom, add 1 H2O molecule on the same side and 2 OH^- ions on the opposite side.

O + H2O ---------> 2OH^-

For each excess H- atom, add 1 OH^- ions on the same side and 1 H2O molecule on the opposite side.

H + OH^-   ---------> H2O

Hence the balanced oxidation - half reaction is

Oxidation - half reaction: NO₂^-(aq) + 2OH^-(aq) ----- > NO₃^-(aq) + H2O + 2e^-

Reduction - half reaction: Cu²⁺(aq) + 2e^- ------- > Cu(s)

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Complete balanced reaction: NO₂^-(aq) + 2OH^-(aq) + Cu²⁺(aq) ------ > NO₃^-(aq) + H2O + Cu(s) (answer)