Question

Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water, and a gas C is evolved. The gas C, when passed through lime water, turns it milky. Identify A, B, and C.

Answer 1

• Salt A is Baking soda (Sodium Hydrogen Carbonate) which will turn to Sodium carbonate (salt B) on heating.
• Gas C turns lime water milky, it must be ${\mathrm{CO}}_2$(carbon dioxide).
• Above baking soda gradually decomposes into sodium carbonate, water, and carbon dioxide.
• Chemical reaction:

${\mathrm{NaHCO}}_{3\left(\mathrm{s}\right)}\underset{{60}^{\circ }\mathrm{C}}{\overset{∆}{\to }}{\mathrm{Na}}_2{\mathrm{CO}}_{3\left(\mathrm{s}\right)}+{\mathrm{CO}}_{2\left(\mathrm{g}\right)}+{\mathrm{H}}_2\mathrm{O}$