Ammonia

In nature, ammonia can be found in both free and mixed forms. When nitrogenous materials degrade in the absence of oxygen, this gas is created. Ammonia gas can also be found in ammonium sulphate and ammonium chloride in combination. Lavoiser had heated the ammonium chloride and calcium hydroxide mixture to produce this gas.

Ammonia has a molecular weight of 17. While nitrogen has a molecular weight of 28 and carbon dioxide has a molecular weight of 44, oxygen has a molecular weight of 32. The gas is therefore lighter than the air.

Laboratory Preparation of Ammonia Gas

In the laboratory, ammonia gas is prepared by heating the mixture of ammonium chloride (NH₄CI) and calcium hydroxide [Ca(OH)₂] in a ratio of 2:1 in a hard glass test tube.

Ammonium chloride + Calcium hydroxide → calcium chloride + water + ammonia

2NH₄Cl (s) +Ca(OH)₂(s) → CaCl₂(s) + 2H₂O (l) + 2NH₃(g)

Apparatus Required:

Hard glass test tube, source of heat, gas jar, stand, lime tower, delivery tube, etc.

Chemicals Required:

Ammonium chloride and Calcium hydroxide

Method/ Procedure

• Gather the equipment and materials needed to prepare ammonia gas in a lab.
• Combine ammonium chloride and calcium hydroxide in a 2:1 ratio, then transfer the mixture into a test tube made of strong glass.
• As indicated in the image, secure a delivery tube with a rubber stopper in the test tube's mouth to create an airtight seal. With the aid of a support, place the hard glass test tube in an angled position.To obtain clean and dry ammonia gas, connect the opposite end of the supply tube to the lime tower.To obtain impure ammonia, we can conduct the experiment without a lime tower.
• Now, slowly heat the mixture and watch for the production of ammonia gas.
• To obtain dry and pure ammonia, a lime tower filled with calcium oxide (CaO) is utilized. Since this gas is very soluble in water, water is not needed to obtain it. Because it is lighter than air, it is gathered by the air moving downward.

Precautions

• To ensure that the water vapor generated during this procedure travels to the lime tower through the delivery tube and keeps the hard glass test tube from breaking, the mouth of the tube should be slightly angled downward.
• A cork should be used to ensure that the hard glass test tube's opening is airtight.
• The gas needs to be routed through a lime tower in order to obtain dry ammonia gas. The gas shouldn't be gathered by dislodging water because it is very soluble in it.

Test of the Gas

• Because the gas is basic, wet red litmus turns blue.
• When a glass rod that has been dipped in strong hydrochloric acid is brought close to the lips. A gas jar filled with ammonia releases white vapors.

Properties of Ammonia

Physical Properties

• The gas is colorless. It smells strongly and strongly like rotting eggs.
• It weighs less than air.
• This gas dissolves very well in water.
• Beacause it is a fundamental gas, wet red litmus turns blue.
• At -33.4°C, ammonia melts and at -78°C, it solidifies.

Do you know?

Ammonia passes through the lime tower to produce pure, dry ammonia because calcium oxide absorbs moisture from ammonia.

Chemical Properties

• Water does not dissolve this gas. When it dissolves in water, ammonium hydroxide is produced.

NH₃ (g) + H₂O (l) → NH₄ OH (aq)

• Ammonium salts are created when ammonia and acids combine.

NH₃ (g) + HCL (aq) → NH₄CL (aq)               Ammonium chloride

2NH₃ (g) + H₂SO₄ (aq) → (NH₄)₂SO₄ (aq)  Ammonium sulphate

• When ammonium solution (NH₄OH) and acid combine, salt and water are produced.

2NH₄OH (aq) + H₂SO₄ (aq) → (NH₄)₂SO₄ (aq) + 2H₂O (l)

NH₄OH (aq) + HCL (aq) → NH₄CL (aq) + H₂O (l)

• Ammonia and carbon dioxide reacts at a high temperature of 1500º and at a high pressure to form urea.

NH₃ (g) + CO₂ (g) → NH₂-CO-NH₂ ( s) + H₂O (l)

[Urea is an important chemical fertilizer.]

• When ammonia burns in the atmosphere of oxygen, it produce nitrogen gas and water.

4NH₃ (g) + 3O₂ (g) → 6H₂O (l) + 2N₂ (g)

• Nitric oxide is produced when a solution of ammonia and oxygen is run through platinum gauze at a temperature of around 800ºC.

4NH₃ (g) + 5O₂(g) → 6H₂O (l) + 2NO (g)

• Sodamide and hydrogen gas are created when ammonia is introduced to molten sodium.

2NH₃(g) + 2Na (S) →2NaNH₂ (s) + H₂(g)

Uses of Ammonia

• Fertilizers such as ammonium phosphate, urea, ammonium nitrate, and sulphate are made with this gas.
• It's employed in the production of plastic, nitric acid, etc.
• Washing soda is made using this gas.
• Ammonium salts are used to produce medicines with it.
• The blue prints on maps are created with ammonia.
• In refrigerators, it serves as a cooling agent.
• It is used as a cleaning agent to get rid of grease, oil, and other types of stains.