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Carbon dioxide is heavier than oxygen. It can be stored as a liquid at high pressure. When
released it spreads over the fire and extinguishes it. Another way to obtain carbon dioxide
is to release a lot of dry powder of chemicals like sodium bicarbonate or potassium
bicarbonate over the fire, the heat of the fire decomposes the chemical to release carbon
dioxide gas and the fire can be extinguished.

We can use fire extinguishers to extinguish the fire. Most commonly used fire extinguisher
other than discussed above is soda acid fire extinguisher. Soda acid fire extinguisher
contains sodium bicarbonate and sulphuric acid. When combined it releases carbon
dioxide gas water and sodium sulphate. The mixture of carbon dioxide and water can be
sprayed over the fire to extinguish the fire. It cuts off the supply of air as carbon dioxide is
heavier than oxygen and water cools the combustible substance.
The reaction can be written as follows.
Sodium bicarbonate + Sulphuric acid Sodium sulphate + Water + arbon dioxide

NaHCO 3+ H 2SO 4Na 2SO 4+ H 2O + CO 2

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