Question

explain,with the help of a labelled diagram,how a soda-acid type fire extinguisher works

Answer 1

A soda-acid type fire extinguisher contains concentrated solution of sodium hydrogen carbonate (NaHCO3) in a small cylinder fitted with a glass bottle filled with sulphuric acid. When fire breaks out, the cylinder is hit on a hard surface to break the bottle. Once the bottle breaks, the acid reacts with sodium hydrogen carbonate to evolve carbon dioxide and water in the form of vapours. Carbon dioxide, being a non-supporter of combustion, forms a blanket over the fire and extinguishes it. Water, because of its cooling effect, brings down the temperature below the ignition temperature to check burning.

Answer 2

Answer:

There are three conditions on which the principle of working of any fire extinguisher works:

(a)- Lowering the combustible substance or material below its ignition temperature.

(b)- By cutting off the supply of air or oxygen.

(c)- Lowering the combustible substance or material at the same time cutting the supply of air or oxygen.

So the soda-acid type fire extinguisher mainly works on the second principle i.e., by cutting off the supply of air or oxygen. Except for the fire caused by electrical or flammable liquid, soda-acid type extinguishers can be used for all types of fire.

The acid used in this is sulfuric acid (

H

2

S

O

4

H2SO4

) and the soda used is baking soda (

NaHC

O

3

NaHCO3

). So when an acid reacts with baking soda it liberates carbon dioxide and thereby increases the percentage of carbon dioxide in the air. Carbon dioxide becomes a barrier to the supply of oxygen.

Soda-acid type fire extinguishers have a bottle that contains sulfuric acid which is supported by a metallic container filled with baking soda. So when this cylinder is inverted the knob opens and the acid comes in contact with baking soda producing a large amount of carbon dioxide. The reaction is:

2NaHC

O

3

+

H

2

S

O

4

→N

a

2

S

O

4

+2

H

2

O+

2NaHCO3+H2SO4→Na2SO4+2H2O+2CO2

So this carbon dioxide cuts off the supply of air or oxygen and hence the fire is extinguished.

Explanation:

hope it helps you.