Nickel-cadmium battery cases and drain surfaces, which have been affected by electrolyte, should be neutralized with a solution of

• A. potassium hydroxide
• B. boric acid
• C. hydrochloric acid
• D. sodium bicarbonate

Answer: (D)

Nickel-cadmium cells use an alkaline electrolyte, potassium hydroxide, which is caustic. To reduce that caustic hazard on battery cases and drain surfaces, you neutralize with a mild neutralizer that converts the base into a less corrosive carbonate. Sodium bicarbonate reacts with the hydroxide to form potassium carbonate, water, and carbon dioxide: 2 KOH + NaHCO3 → K2CO3 + H2O + CO2. The result is a much less aggressive residue that’s easier to rinse away. Using a strong acid would create heat and potentially fumes, and while boric acid could also neutralize, baking soda is the common, practical choice for this cleanup. After neutralization, flush with water and wipe clean.