Ammonia, Nitric Acid, and Nitrate Salts

Ammonia (NH₃)

Ammonia is a colorless gas with a pungent smell. It is an important compound in the chemical industry.

Laboratory Preparation

• Ammonia can be prepared by heating ammonium chloride (NH₄Cl) with calcium hydroxide (Ca(OH)₂).
• Equation: $$\text{2NH}_4\text{Cl} + \text{Ca(OH)}_2 \rightarrow \text{CaCl}_2 + 2\text{H}_2\text{O} + 2\text{NH}_3$$

Industrial Preparation (Haber Process)

• The Haber process combines nitrogen and hydrogen gases under high pressure and temperature in the presence of an iron catalyst to produce ammonia.
• Equation: $$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$$
• Conditions: 200 atm pressure, 450°C temperature, iron catalyst.

Nitric Acid (HNO₃)

Laboratory Preparation

• Nitric acid can be prepared by heating potassium nitrate (KNO₃) with concentrated sulfuric acid (H₂SO₄).
• Equation: $$\text{KNO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{KHSO}_4 + \text{HNO}_3$$

Industrial Preparation (Ostwald Process)

• The Ostwald process involves the oxidation of ammonia to produce nitric acid.
• Steps:
  1. Ammonia is oxidized to nitrogen monoxide (NO).
  2. NO is further oxidized to nitrogen dioxide (NO₂).
  3. NO₂ is absorbed in water to form nitric acid.
• Overall Equation: $$4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O}$$

Nitrate Salts

Action of Heat on Nitrate Salts

• When heated, nitrate salts decompose to produce different products depending on the metal involved.
• Example: $$\text{2KNO}_3 \rightarrow 2\text{KNO}_2 + \text{O}_2$$
• For some metals, nitrates decompose to form metal oxides, nitrogen dioxide, and oxygen.