Question

Name the following:

Gas evolved when calcium hydroxide and ammonium chloride are heated.

Answer 1

• In a round-bottomed flask, a 2:3 by weight mixture of ammonium chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$ and dry slaked lime $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$ is heated. Ammonia gas $\left({\mathrm{NH}}_3\right)$ is produced and fed through a tower containing dry quicklime$\left(\mathrm{CaO}\right)$.
• The reaction involved is:
  $2{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+\mathrm{Ca}\left(\mathrm{OH}{)}_2\left(\mathrm{s}\right)\stackrel{\text{Heat}}{⟶}{\mathrm{CaCl}}_2\right(\mathrm{aq})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+2{\mathrm{NH}}_3(\mathrm{aq})\uparrow$
• Therefore, ammonia gas is evolved when calcium hydroxide and ammonium chloride are heated.