Question

In a particular redox reaction, no2– is oxidized to no3– and ag is reduced to ag. complete and balance the equation for this reaction in acidic solution. phases are optional.

Answer 1

Reduction Reaction:

                     Ag⁺  +  1e⁻   →   Ag    ------ (1)

Oxidation Reaction:

                    NO₂⁻  →    NO₃⁻  +  2e⁻

Balance Oxygen atoms, by adding H₂O to side having less number of O atoms, and H⁺ to side having greater number of O atoms.

                    NO₂⁻  +  H₂O  →    NO₃⁻  +  H⁺  +  2e⁻

Balance the H⁺'s,

                    NO₂⁻  +  H₂O  →    NO₃⁻  +  2 H⁺  +  2e⁻    ------ (2)

Multiply eq. 1 by 2 to balance the number of electrons in overall reaction.

                     2 Ag⁺  +  2e⁻   →   2 Ag    ----- (3)

Compare eq. 2 and 3,

                    NO₂⁻  +  H₂O  →    NO₃⁻  +  2 H⁺  +  2e⁻
                    2 Ag⁺  +  2e⁻   →   2 Ag
             _______________________________________

                    NO₂⁻  +  H₂O + 2 Ag⁺  →   NO₃⁻ +  2 Ag + 2 H⁺