Question

Ammonia gas can be dried over by:

• A. $Ca{Cl}_2$
• B. conc. $H_{2}S{O}_4$
• C. $P_2{O}_5$
• D. quick lime

Answer 1

The correct option is D quick lime

Ammonia is prepared by heating a mixture of calcium hydroxide and ammonium chloride.

$Ca{\left(OH\right)}_2\left(s\right)+2N{H}_{4}Cl\left(s\right)⟶Ca{Cl}_2\left(s\right)+2H_{2}O\left(l\right)+2N{H}_3\left(g\right)$

Concentrated sulphuric acid conc. $H_{2}S{O}_4$ and anhydrous calcium chloride $Ca{Cl}_2$ are not used to dry ammonia because they react with it. The gas is passed through fresh quicklime (solid calcium oxide lumps) to effectively dry it. Ammonia is collected by upward delivery as it is lighter than air.