Question

Why do we feel the pungent smell when the pack of bleaching powder is opened?

Answer 1

When exposed to air, bleaching powder gives a smell of chlorine. This is because bleaching powder reacts with carbon dioxide from the atmosphere to produce calcium carbonate and chlorine gas.

The reaction which occurs is,

$CaOC{l}_2+C{O}_2\to CaC{O}_3+C{l}_2$

Chlorine gas evolved is the reason for the pungent smell in this reaction.