Chemistry Chapter 19: Ammonia

The reaction between nitrogen and hydrogen to form ammonia is irreversible.

What is the chemical equation for the reaction between nitrogen and hydrogen to form ammonia?

Which of the following statements about reversible reactions is correct?

What is the role of a catalyst in the Haber process?

The optimal pressure for the manufacture of ammonia in the Haber process is _______.

What raw materials are needed for the manufacturing of ammonia by the Haber process?

Which of the following temperatures is used in the Haber process?

What happens to unreacted nitrogen and hydrogen in the Haber process?

What is produced when solid ammonium chloride is heated?

The reaction that displaces ammonia from ammonium salts involves heating the salt with an _______.

Match the following terms with their descriptions:

Reversible Reactions

Some chemical reactions can proceed in both directions; these are called reversible reactions.
The formation of ammonia is an example: N2(g) + 3H2(g) ⇌ 2NH3(g).
The forward reaction involves nitrogen and hydrogen combining to form ammonia.
The backward reaction is the decomposition of ammonia back to nitrogen and hydrogen.
Ammonium chloride can decompose into ammonia and hydrogen chloride upon heating and reform upon cooling:
- NH4Cl(s) ⇌ NH3(g) + HCl(g).

Manufacturing Ammonia by the Haber Process

Ammonia is manufactured using the Haber process, which combines nitrogen and hydrogen.
Raw materials:
- Nitrogen is sourced from air, typically via fractional distillation.
- Hydrogen is obtained from the cracking of petroleum.
Optimal conditions for production include high pressure (250 atm) and a temperature of 450°C, using finely divided iron as a catalyst.
The reaction is exothermic, yet only about 10-15% of reactants convert into ammonia.
The mixture of gases undergoes multi-step processing:
- Mixed in a 1:3 volume ratio (N2:H2).
- Compressed to 250 atm and heated to 450°C.
- Ammonia produced is condensed into liquid form.
- Unreacted nitrogen and hydrogen are recycled back into the process for further reactions.

Displacement of Ammonia from its Salts

Heating an ammonium salt with an alkali displaces ammonia from the salt.
General reaction: NH4Cl(s) + NaOH(aq) → NH3(g) + H2O(l) + NaCl(aq).
Common ammonium salts include ammonium nitrate and ammonium sulfate.
Common alkalis used in displacement reactions include sodium hydroxide and calcium hydroxide.

Explore the fascinating chemistry of ammonia in Chapter 19. This section covers reversible reactions, the manufacturing process of ammonia via the Haber process, and the displacement of ammonia from its salts. Perfect for students looking to deepen their understanding of chemical reactions involving ammonia.