Question

Which compound does not give ammonia gas on reaction with water ?

• A. ${\mathrm{Mg}}_3{\mathrm{N}}_2$
• B. $\mathrm{AlN}$
• C. ${\mathrm{CaCN}}_2$
• D. $\mathrm{Ca}{\left(\mathrm{CN}\right)}_2$

Answer 1

The correct option is D

$\mathrm{Ca}{\left(\mathrm{CN}\right)}_2$

Explanation for correct option:

Option (D) $\mathrm{Ca}{\left(\mathrm{CN}\right)}_2$

• The following reaction takes place when $\mathrm{Ca}{\left(\mathrm{CN}\right)}_2$ is reacted with water:

$\underset{\mathrm{Calcium}\mathrm{cyanide}}{\mathrm{Ca}{\left(\mathrm{CN}\right)}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Calcium}\mathrm{Hydroxide}}{\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}\mathrm{cyanide}}{2\mathrm{HCN}\left(\mathrm{g}\right)}$

• It can be seen that ammonia is not produced in the reaction.
• Hence, option D is the correct answer.

Explanation for the incorrect options:

Option A: ${\mathrm{Mg}}_3{\mathrm{N}}_2$

• The following reaction takes place when ${\mathrm{Mg}}_3{\mathrm{N}}_2$ is reacted with water:

$\underset{\mathrm{Magnisium}\mathrm{Nitride}}{M{g}_3{\mathrm{N}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{6{\mathrm{H}}_2\mathrm{O}}\left(\mathrm{l}\right)\to \underset{\mathrm{Magnesium}\mathrm{Hydroxide}}{3\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Ammonia}}{2{\mathrm{NH}}_3}\left(\mathrm{g}\right)$

• It can be seen that ammonia is produced in the reaction.
• Hence, option A is incorrect.

Option B: $\mathrm{AlN}$

• The following reaction takes place when $\mathrm{AlN}$ is reacted with water:

$\underset{\mathrm{Aluminium}\mathrm{Nitride}}{\mathrm{AlN}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Aluminium}\mathrm{Hydroxide}}{\mathrm{Al}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Ammonia}}{{\mathrm{NH}}_3\left(\mathrm{g}\right)}$

• It can be seen that ammonia is produced in the reaction.
• Hence, option B is incorrect.

Option C: ${\mathrm{CaCN}}_2$

• The following reaction takes place when ${\mathrm{CaCN}}_2$ is reacted with water:

$\underset{\mathrm{Calclium}\mathrm{cynamide}}{{\mathrm{CaCN}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Calcium}\mathrm{Carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Ammonia}}{2{\mathrm{NH}}_3\left(\mathrm{g}\right)}$

• It can be seen that ammonia is produced in the reaction.
• Hence, option C is incorrect.

Hence, the correct option is D $\mathrm{Ca}{\left(\mathrm{CN}\right)}_2$