a) Name the gas released at anode during chlor - alkali process and mention the uses of this gas.
b) Which gas is released when sodium carbonate reacts with hydrochloric acid? How do you test this gas? Write the word equation for this reaction.

Explanation

(a) Chlorine gas is released at anode during chloro-alkali process.
Uses :
It is used in water treatment.
Manufacture of PVC.
Used as disinfectants and pesticides.
Used in swimming pools, CFC.s etc.
(b) Carbon dioxide `(CO_2) ` gas is evolved when sodium carbonate reacts with hydrochloric acid. When the gas is passed through lime water it turns milky (showing that it is carbon dioxide) due to the formation of insoluble calcium carbonate.
Metal carbonate / Metal hydrogen carbonate + Acid `to` Salt + Carbondioxide + Water.