NDA Chemistry · Industrial and Applied Chemistry
Industrial Gases, Manufacturing and Reactions
The composition and use of the industrially important gas mixtures — water gas, syngas, producer gas — plus the Haber process for ammonia, the gases that cause acid rain, and the chemistry behind airbags.
Why this matters
The largest subtopic in the chapter — eight PYQs, mostly EASY/MODERATE. The bank asks the composition of a named gas mixture (water gas, syngas), the name of a manufacturing process (Haber–Bosch), or a one-fact reaction (sodium azide in airbags). All recall: learn the gas-mixture table and the process names.
Concept 1 of 3: Water gas, syngas and producer gas
Definition
The named industrial gas mixtures and what they contain:
- Water gas = CO + H₂ (made by passing steam over red-hot coke). Also called syngas (synthesis gas), the feedstock for many syntheses.
- Producer gas = CO + N₂ (made by passing limited air over red-hot coke).
- Coal gas = H₂ + CH₄ + CO (made by the destructive distillation of coal).
- Natural gas is mostly methane (CH₄).
| Gas mixture | Composition | How it is made |
|---|---|---|
| Water gas (syngas) | CO + H₂ | Steam over red-hot coke Water gas and syngas are the SAME mixture: carbon monoxide + hydrogen. Do not pick CO + H₂O. |
| Producer gas | CO + N₂ | Limited air over red-hot coke |
| Coal gas | H₂ + CH₄ + CO | Destructive distillation of coal |
| Natural gas | Mainly CH₄ (methane) | Underground deposits |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 1 · Industrial and Applied Chemistry · Industrial Gases, Manufacturing and Reactions
Water gas is CO + H₂, not CO + H₂O
Syngas = water gas
Concept 2 of 3: Named manufacturing processes
Definition
The high-frequency industrial processes:
- Ammonia (NH₃) → Haber–Bosch process (N₂ + 3H₂ → 2NH₃, with an iron catalyst).
- Sulphuric acid (H₂SO₄) → Contact process.
- Nitric acid (HNO₃) → Ostwald process.
- Sodium carbonate (washing soda) → Solvay process.
| Product | Process | Key reaction / catalyst |
|---|---|---|
| Ammonia (NH₃) | Haber–Bosch | N₂ + 3H₂ → 2NH₃, iron catalyst Ammonia is manufactured by the Haber (Haber–Bosch) process. |
| Sulphuric acid (H₂SO₄) | Contact | 2SO₂ + O₂ → 2SO₃, V₂O₅ catalyst |
| Nitric acid (HNO₃) | Ostwald | Catalytic oxidation of ammonia |
| Washing soda (Na₂CO₃) | Solvay | Ammonia-soda process |
Practice this concept4 quick reps
The same idea in a real exam question:
Example 2 · Industrial and Applied Chemistry · Industrial Gases, Manufacturing and Reactions
Haber makes ammonia; Contact makes sulphuric acid
Concept 3 of 3: Applied gas facts — acid rain, airbags, atmosphere
Definition
The applied one-fact recall:
- Acid rain is caused mainly by sulphur dioxide (SO₂) and nitrogen oxides (NOₓ), which form sulphuric and nitric acids in rain.
- Airbags inflate by the rapid decomposition of sodium azide: 2NaN₃ → 2Na + 3N₂. The sudden release of nitrogen gas fills the bag.
- Atmosphere abundance (by volume): nitrogen ≈ 78% (first), oxygen ≈ 21% (second), argon ≈ 0.9%, then carbon dioxide.
- Paper manufacture is quality-tested by physical tests of mechanical/strength, surface, optical and permeability properties.
| Phenomenon | Chemistry / fact | Answer the bank wants |
|---|---|---|
| Acid rain | SO₂ and NOₓ dissolve in rain | Sulphur dioxide (SO₂) The single biggest cause of acid rain in NDA options is sulphur dioxide. |
| Airbag inflation | 2NaN₃ → 2Na + 3N₂ | Sodium azide → nitrogen gas Airbags work by sodium azide decomposing into nitrogen gas. |
| 2nd most abundant atmospheric gas | N₂ ≈ 78%, O₂ ≈ 21% | Oxygen Nitrogen is first (most abundant); OXYGEN is second. |
| Paper physical testing | Mechanical, surface, optical, permeability | All four properties tested |
Practice this concept4 quick reps
The same idea in a real exam question:
Example 3 · Industrial and Applied Chemistry · Industrial Gases, Manufacturing and Reactions
Oxygen is second, nitrogen is first
Airbags release nitrogen, not CO₂
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (3)
Water gas, syngas and producer gas4 rows
| Gas mixture | Composition | How it is made |
|---|---|---|
| Water gas (syngas) | CO + H₂ | Steam over red-hot coke Water gas and syngas are the SAME mixture: carbon monoxide + hydrogen. Do not pick CO + H₂O. |
| Producer gas | CO + N₂ | Limited air over red-hot coke |
| Coal gas | H₂ + CH₄ + CO | Destructive distillation of coal |
| Natural gas | Mainly CH₄ (methane) | Underground deposits |
Named manufacturing processes4 rows
| Product | Process | Key reaction / catalyst |
|---|---|---|
| Ammonia (NH₃) | Haber–Bosch | N₂ + 3H₂ → 2NH₃, iron catalyst Ammonia is manufactured by the Haber (Haber–Bosch) process. |
| Sulphuric acid (H₂SO₄) | Contact | 2SO₂ + O₂ → 2SO₃, V₂O₅ catalyst |
| Nitric acid (HNO₃) | Ostwald | Catalytic oxidation of ammonia |
| Washing soda (Na₂CO₃) | Solvay | Ammonia-soda process |
Applied gas facts — acid rain, airbags, atmosphere4 rows
| Phenomenon | Chemistry / fact | Answer the bank wants |
|---|---|---|
| Acid rain | SO₂ and NOₓ dissolve in rain | Sulphur dioxide (SO₂) The single biggest cause of acid rain in NDA options is sulphur dioxide. |
| Airbag inflation | 2NaN₃ → 2Na + 3N₂ | Sodium azide → nitrogen gas Airbags work by sodium azide decomposing into nitrogen gas. |
| 2nd most abundant atmospheric gas | N₂ ≈ 78%, O₂ ≈ 21% | Oxygen Nitrogen is first (most abundant); OXYGEN is second. |
| Paper physical testing | Mechanical, surface, optical, permeability | All four properties tested |
Watch out for (5)
- Water gas is CO + H₂, not CO + H₂O→ Water gas, syngas and producer gas
- Syngas = water gas→ Water gas, syngas and producer gas
- Haber makes ammonia; Contact makes sulphuric acid→ Named manufacturing processes
- Oxygen is second, nitrogen is first→ Applied gas facts — acid rain, airbags, atmosphere
- Airbags release nitrogen, not CO₂→ Applied gas facts — acid rain, airbags, atmosphere
Test yourself on Industrial and Applied Chemistry
10 past NDA questions from this chapter, timed at 10 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.