Writing Half Equations for Basic Aqueous Solutions Chemistry Tutorial
To write a balanced oxidation or reduction reaction for a species in basic or alkaline aqueous solution:
- Write a skeletal equation for the oxidation or reduction equation based on the information provided.
- Balance the half-reaction equation according to the following sequence:
(i) Balance all atoms other than H and O by inspection
(ii) Balance O atoms by adding H2O to the appropriate side
(iii) Balance the H atoms:
⚛ add H2O molecule to the side deficient in H
⚛ add one OH- ion to the opposite side, for each H atom needed.
You may need to cancel out H2O molecules duplicated on both sides of the equation at this point.
- Balance the charge by adding electrons (e-) to the side deficient in negative charge.