Iron (II) ions, Fe ^2

Question

Iron (II) ions, Fe ^2 , reduce dichromate ions, Cr2O7^2-, in acidic solution to chromium (III) ions, Cr^3 , forming ferric ions, Fe^3 .

Write the balanced net ionic equation for the reaction, H or H2O may be added as necessary.

Answer 1

Oxidation:  Fe2+ ==>  Fe3+ + e-

Reduction: Cr2O7 2- + 14H+ + 6e-  ==>  2Cr3+ + 7H2O

Multiply the oxidation step by 6 to cancel the electrons, then add to the reduction equation.

6Fe2+ + Cr2O7 2- + 14H+ ==>  6Fe3+ + 2Cr3+ + 7H2O