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.

All Industrial and Applied Chemistry notes NDA Chemistry strategy

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

Intuition

Industry uses several cheap gas mixtures made from coke, steam and air. The bank tests their composition — what two or three gases each mixture contains — so learn the pairs.

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

Try it yourself

A gas mixture is made by passing limited air over red-hot coke. Name it and give its composition.

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Water gas is a mixture of which two gases?
2.
Syngas (synthesis gas) is a mixture of which two gases?
3.
Producer gas is a mixture of which two gases?
4.
Natural gas is mainly which compound?

From the bank · past-year question

Example 1Industrial and Applied ChemistryEASY

Which one of the following is known as water gas ?

[Q109 · Sep · 2025]

Water gas is CO + H₂, not CO + H₂O

Water gas is made USING steam (H₂O over coke), but the PRODUCT mixture is carbon monoxide + hydrogen (CO + H₂). The distractor 'CO + H₂O' describes the reactants, not the gas.

Syngas = water gas

'Syngas' and 'water gas' are two names for the same CO + H₂ mixture. If a question names one, the answer is the same composition as the other.

Drill 2 more on water gas, syngas and producer gas

Concept 2 of 3

Named manufacturing processes

Intuition

Each industrial chemical has a named process behind it. The bank asks 'which process makes ammonia / sulphuric acid?' — learn the process↔product pairs.

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

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Ammonia is manufactured by which process?
2.
Which catalyst is used in the Haber process?
3.
Sulphuric acid is manufactured by which process?
4.
Nitric acid is manufactured by which process?

From the bank · past-year question

Example 2Industrial and Applied ChemistryEASY

Which among the following is the popular method for manufacture of ammonia?

[Q110 · Apr · 2023]

Haber makes ammonia; Contact makes sulphuric acid

Do not swap them. The Haber–Bosch process makes NH₃; the Contact process makes H₂SO₄; the Ostwald process makes HNO₃. The bank pairs the wrong product with a process as a distractor.

Concept 3 of 3

Applied gas facts — acid rain, airbags, atmosphere

Intuition

A scatter of one-fact reactions and atmospheric facts: which gas causes acid rain, what reaction inflates an airbag, what is the second-most-abundant atmospheric gas, and how paper quality is tested. Memorise each pair.

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

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Which gas is the main cause of acid rain?
2.
Airbags inflate using which chemical conversion?
3.
Which gas is SECOND most abundant in Earth's atmosphere?
4.
Which gas is MOST abundant in Earth's atmosphere?

From the bank · past-year question

Example 3Industrial and Applied ChemistryEASY

Airbags work on the principle of a chemical reaction triggered by the impact producing a gaseous product that causes a sudden volume change. Which one among the following chemical conversions is responsible for this?

[Q115 · Apr · 2023]

Oxygen is second, nitrogen is first

Nitrogen (≈ 78%) is the most abundant atmospheric gas; OXYGEN (≈ 21%) is second. A question asking for the second-most-abundant gas wants oxygen, not nitrogen.

Airbags release nitrogen, not CO₂

The gas that inflates an airbag is nitrogen (N₂), produced by sodium azide decomposing. It is not carbon dioxide.

Drill 3 more on applied gas facts — acid rain, airbags, atmosphere

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

Mastery check — 5 interleaved questions

Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.

Example 1Industrial and Applied ChemistryEASY

Water gas is a mixture of :

[Q98 · Apr · 2024]

Example 2Industrial and Applied ChemistryEASY

Which one of the following gases is placed second in respect of abundance in the Earth's atmosphere?

[Q117 · Sep · 2017]

Example 3Industrial and Applied ChemistryMODERATE

Which one of the following is called 'syngas'?

[Q66 · Sep · 2018]

Example 4Industrial and Applied ChemistryMODERATE

Which of the following is/are physical test(s) employed for manufacture of paper? I. Mechanical and strength properties II. Surface properties III. Optical properties IV. Permeability to fluids

[Q89 · Apr · 2026]

Example 5Industrial and Applied ChemistryEASY

Which one of the following is a cause of acid rains?

[Q138 · Sep · 2017]

Drill every past-year question on this subtopic

8 questions from the bank — paginated, with cart and Word-export support.

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