Question

Baking soda is used in a small amount for making bread and cake. It helps to make these soft and spongy. An aqueous solution of baking soda turns red litmus blue. It is also used in soda-acid fire extinguishers.

How does it help in extinguishing fire?

Answer 1

• When sodium hydrogen carbonate is heated sodium carbonate will produce a large amount of carbon dioxide will produce.
• $$\begin{gathered} 2{\mathrm{NaHCO}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+2{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{sodium}\mathrm{bicarbonate}\mathrm{sulfuric}\mathrm{acid}\mathrm{sodium}\mathrm{sulphate}\mathrm{water}\mathrm{carbondioxide} \end{gathered}$$
• A fire extinguisher has a large iron vessel in which sodium bicarbonate is stored.
• The iron vessel has a nozzle through which discharge of sodium bicarbonate (baking soda) takes place.
• There is a sulfuric acid bottle also attached with a knob inside the iron vessel and when the knob is lifted sulfuric acid drops down in baking soda and following the above reaction takes place forming sodium sulfate, water, and carbon dioxide, where the water helps in extinguishing the fire.