A chemical A is used for the preparation of washing soda to recover ammonia. When CO2 is bubbled through an aqueous solution of A, the solution turns milky. It is used in white washing due to disinfectant nature. What is the chemical formula of A?

Chemical A used in the preparation of washing soda Na2CO3 to recover ammonia is Ca(OH)2. It is a reaction involved in the Solvay process for preparation of sodium carbonate.

2NH4Cl + Ca(OH)2 2NH3 + CaCl2 + H2O


When CO2 is bubbled through a solution of Ca(OH)2, it forms milky precipitate of CaCO3.


Ca(OH)2 + CO2 CaCO3 + H2O


Ca(OH)2 is used as slaked lime as white wash due its disinfectant nature.

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