BALANCING REDOX EQUATIONS

A. OXIDATION NUMBER METHOD 1. Identify the elements being oxidized and reduced by assigning oxidation numbers. 2. Determine the number of electrons gained or lost per formula unit of reducing agent (RA) and oxidizing agent (OA). 3. Adjust the coefficient of the RA and OA in order to make the number of electrons lost equal to the number of electrons gained. 4. Balance the elements that changed in oxidation number by adjusting the coefficients of the substances on the right side of the equation which contain these elements. 5. Balance the rest of the equation by inspection, The usual procedure is to balance all other atoms except H and O first, followed by H and O. 6. Check if all atoms are balanced.

B. HALF EQUATION METHOD 1. Write the equations for the oxidation and reduction half reactions. 2. Balance each half-reaction separately. a. Balance all elements except hydrogen and oxygen. b. Balance oxygen using H2O. c. Balance hydrogen using H+. d. Change H+ to H3O+ by adding H2O. e. Balance the charges using electrons. 3. If necessary, multiply each half reaction by the appropriate integer so that the electrons lost in the oxidation half reaction is equal to the electrons gained in the reduction half-reaction. 4. Eliminate duplications on both sides of the equation. 5. (Only in basic solution – add OH- equal to H3O+ to both sides.) 6. Check the number of atoms of each element and total charge.