Question

Balance the following equation by the ion electron method.

\[\ce{C2O^2-_4 + Cr2O^2-_7 -> Cr^3+ + CO2}\] (in acid medium)

Answer 1

\[\ce{C^{+3}_2O^2-_4 -> C^{+4}O2}\] ......(1)

\[\ce{Cr^{+6}_2O^2-_7 -> Cr^3+}\] .......(2)

\[\ce{C2O^2-_4 -> 2CO2 + 2e^-}\] .....(3)

\[\ce{Cr2O^2-_7 + 14H^+ -> 2Cr^3+ + 7H2O}\] ......(4)

\[\ce{3C2O^2-_4 -> 6CO2 + 6e^-}\] ........(5) [Eq. (3) × 3]

\[\ce{Cr2O^2-_7 + 14H^+ + 6e^- -> 2Cr^3+ + 7H2O}\] .........(4)

\[\ce{Cr2O^2-_7 + 3C2O^2-_4 + 14H^+ -> 2Cr^3+ + 6CO2 + 7H2O}\]