The following questions are pertaining to the laboratory preparation of Ammonia gas from Magnesium nitride:

(a) Write a balanced chemical equation for its preparation.

(b) Why is this method seldom used?

(c) How do you identify the gas formed?

(a) Mg₃N₂ + 6H₂O ⟶ 3Mg(OH)₂ + 2NH₃

(b) As nitrides are expensive, hence the method is seldom used.

(c) Ways in which ammonia gas can be identified is:

1. It has a sharp characteristic odour.
2. It turns:
   
   1. moist red litmus blue,
   2. moist turmeric paper brown,
   3. phenolphthalein solution pink.
3. When a glass rod dipped in conc. HCl is brought near the mouth of the jar containing NH₃, dense white fumes of ammonium chloride are formed.
   NH₃ + HCl ⟶ NH₄Cl