1. Laboratory Preparation:
* Reaction of ammonium salts with strong bases: This is the most common laboratory method. Ammonium chloride (NH₄Cl) or ammonium sulfate ((NH₄)₂SO₄) is reacted with a strong base like sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)₂) to produce ammonia gas.
* Equation: 2NH₄Cl + Ca(OH)₂ → CaCl₂ + 2H₂O + 2NH₃
* Heating of ammonium salts: Ammonium salts like ammonium nitrate (NH₄NO₃) decompose upon heating to produce ammonia gas.
* Equation: NH₄NO₃ → N₂O + 2H₂O
2. Industrial Production:
* Haber-Bosch Process: This is the primary industrial method for producing ammonia. It involves reacting nitrogen gas (N₂) with hydrogen gas (H₂) under high pressure (around 200 atm) and temperature (around 500°C) in the presence of an iron catalyst.
* Equation: N₂ + 3H₂ ⇌ 2NH₃
General Procedure for Laboratory Preparation:
1. Set up: A round-bottom flask is connected to a delivery tube that leads to a gas collection apparatus (like an inverted graduated cylinder filled with water).
2. Reaction mixture: Add ammonium salt and the strong base to the flask.
3. Heating: Heat the flask gently to initiate the reaction.
4. Gas collection: The ammonia gas produced will displace water in the graduated cylinder.
5. Drying: The ammonia gas can be dried by passing it through a drying tube containing calcium chloride (CaCl₂).
Safety Precautions:
* Ammonia gas is a strong irritant and can cause respiratory problems. Use a fume hood during the preparation.
* Avoid contact with ammonia gas and its solutions.
* Wear appropriate safety equipment like gloves, goggles, and lab coats.
Note: The exact procedures and safety precautions may vary depending on the specific method and setup used. It is crucial to consult appropriate laboratory manuals and safety guidelines before attempting to prepare ammonia gas.
