Dry chemical agents are fire extinguishing substances that interrupt the chemical reaction of a fire. They are typically composed of powdered chemicals, such as sodium bicarbonate, potassium bicarbonate, or monoammonium phosphate. These agents are effective against various types of fires, including Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical fires). When applied, dry chemical agents create a barrier between the fuel and the oxygen, helping to smother the flames. They are commonly found in portable fire extinguishers and are favored for their versatility and ease of use. However, they can leave a residue that may require cleanup after use.