Question

Name the gas evolved when the following mixtures are heated:
(i) Calcium hydroxide and ammonium chloride
(ii) Sodium nitrate and ammonia chloride

Answer 1

(i) Reaction of calcium hydroxide $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$ and ammonium chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$:

• Ammonia $\left({\mathrm{NH}}_3\right)$ is generated on reaction of calcium hydroxide and ammonium chloride.
• $2{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+\mathrm{Ca}\left(\mathrm{OH}{)}_2\left(\mathrm{aq}\right)\stackrel{\mathrm{Heat}}{\to }{\mathrm{CaCl}}_2\right(\mathrm{s})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+2{\mathrm{NH}}_3(\mathrm{aq})\uparrow$
• Therefore, ammonia gas is evolved when mixture of calcium hydroxide and ammonium chloride are heated.

(ii) Reaction of sodium nitrate$\left({\mathrm{NaNO}}_3\right)$ and ammonia chloride$\left({\mathrm{NH}}_4\mathrm{Cl}\right)$:

• Sodium chloride $\left(\mathrm{NaCl}\right)$ is formed on reaction of sodium nitrate and ammonium chloride.
• ${\mathrm{NaNO}}_3\left(\mathrm{aq}\right)+{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)\to \mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{N}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$
• Therefore, nitrogen is evolved when mixture of sodium nitrate and ammonium chloride are heated.