What chemical reaction occurs when wet chemical extinguishing agent is applied to fats and oils?

• A. Freezing reaction
• B. Polymerization
• C. Saponification forming a soapy layer
• D. Vaporization

Answer: (C)

When a wet chemical extinguishing agent is applied to fats and oils, the key process is saponification. The alkaline component (commonly potassium acetate) reacts with the triglycerides in the fat to form potassium fatty acid salts, i.e., soap, plus glycerol. That soap forms a thick, soapy layer on the surface, which blankets the oil, separates the fuel from the air, and helps smother the flame. The wetting action also spreads and cools the surface, further preventing re-ignition. Other options don’t describe the chemical change that occurs with fats and oils in this context (they’re not about freezing, polymerization, or vaporization).