Baking soda is also known as sodium hydrogen carbonate (NaHCO3), sodium bicarbonate, sweet soda and food soda. It is also an ingredient of antacids. Due to its alkaline nature, it relieves the depression of excessive acid in the stomach.It is also used in soda-acid fire extinguishers.

Soda-acid fire extinguishers are a type of portable fire extinguisher commonly used to extinguish small fires. They work by releasing a stream of water mixed with a chemical agent to suppress the fire. The chemical agent used in a soda-acid fire extinguisher is baking soda.

Explanation:
1. Soda-acid fire extinguisher composition:
- Soda-acid fire extinguishers consist of two main components: a container filled with water and a separate container filled with a mixture of baking soda (sodium bicarbonate) and a weak acid.
- The two containers are connected by a tube or hose, and when the extinguisher is activated, the acid is released into the water, causing a chemical reaction.

2. Chemical reaction:
- When the baking soda (sodium bicarbonate) reacts with the weak acid (typically tartaric acid or sulfuric acid), it produces carbon dioxide gas.
- The carbon dioxide gas generated rapidly expands, creating pressure inside the extinguisher, which propels the water and the gas mixture towards the fire.

3. Suppression mechanism:
- The water in the extinguisher cools down the fire, reducing the temperature below the point at which combustion can occur.
- The carbon dioxide gas helps to suffocate the fire by displacing oxygen, which is necessary for combustion.

4. Advantages of baking soda:
- Baking soda (sodium bicarbonate) is commonly used in soda-acid fire extinguishers because it is non-toxic, non-corrosive, and effective against certain types of fires, such as Class B (flammable liquids) and Class C (electrical) fires.
- It is also readily available and affordable, making it a practical choice for fire extinguishers.

In conclusion, baking soda is used in a soda-acid fire extinguisher because it reacts with a weak acid to produce carbon dioxide gas, which helps to suppress the fire by cooling it down and displacing oxygen. Baking soda is a safe and effective chemical agent for extinguishing certain types of fires.