Q23 of 30 Page 34

(i) Write the chemical equation to represent the action of atmospheric CO2 gas and bleaching powder when left exposed in the open. (ii) State for what purpose bleaching powder is used in water treatment plants. (iii) Why does bleaching powder smell of chlorine when exposed to air?

(i) When bleaching powder reacts with carbon dioxide gas, form calcium carbonate and chlorine. The reaction is:


CaOCl2 + CO2 CaCO3 + Cl2


(ii) Bleaching powder is used for disinfecting drinking water and to kill germs present in the water which spreads a number of diseases. It makes the water free of germs.


(iii) When exposed to air, bleaching powder reacts with carbon dioxide to form calcium carbonate and chlorine. Due to the presence of chlorine, bleaching powder smells like chlorine.


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