NDA Chemistry · Teaching notes
Industrial and Applied Chemistry — NDA Chemistry
Industrial Chemistry is pure named-fact recall — 28 PYQs across 2017–2026, almost every one a 'which is correct / which is NOT' about a manufactured gas, a fertilizer, a building material, a paint additive, or an alloy. There is no derivation to do; the marks go to whoever has memorised the table. The chapter teaches in five movements, grouped by industry: (1) Industrial gases, manufacturing and reactions — water gas, syngas, the Haber process, acid-rain gases and airbag chemistry; (2) Fertilizers — the nutrient each fertilizer supplies (N, P or K), how superphosphate and nitrolim are made, and the urea traps; (3) Cement, glass and building materials — what glass and Portland cement are made from, and the property statements the bank loves to falsify; (4) Paints and coatings — the role of each additive (pigment, binder, drier, thinner, anti-skinning, antifoaming), the chapter's hardest pocket; (5) Common industrial substances and alloys — plaster of Paris, borax, soft soap, and the composition of solder. Most concepts are reference tables: learn the table, win the marks.
Subtopic notes
Industrial Gases, Manufacturing and Reactions
8 PYQsThe 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.
Open note
Fertilizers
5 PYQsThe chemicals that supply the three plant nutrients — nitrogen (N), phosphorus (P) and potassium (K) — to soil, which nutrient each fertilizer carries, and how the common ones are manufactured.
Open note
Cement, Glass and Building Materials
6 PYQsWhat glass and Portland cement are actually made of — their raw materials, the chemical compounds inside set cement, and the property statements (glass is a supercooled liquid; pyrex beats soda glass) the bank loves to test.
Open note
Paints and Coatings
4 PYQsWhat each ingredient in a paint actually does — the pigment that colours, the binder that forms the film, the thinner that thins, the drier that speeds drying, and the additives (anti-skinning, antifoaming) that fix storage problems.
Open note
Common Industrial Substances and Alloys
5 PYQsThe composition of everyday industrial substances and alloys — plaster of Paris, borax, soft soap and solder — plus the raw materials of Portland cement, all answered by knowing one formula or element list per item.
Open note
PYQ weightage by concept
12 concepts · 28 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
12 concepts · 28 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Applied gas facts — acid rain, airbags, atmosphere | 4 | 14% |
| Water gas, syngas and producer gas | 3 | 11% |
| Named manufacturing processes | 1 | 4% |
| Concept | PYQs | Share |
|---|---|---|
| Which nutrient each fertilizer supplies | 3 | 11% |
| How superphosphate and nitrolim are made | 2 | 7% |
| Concept | PYQs | Share |
|---|---|---|
| Glass — nature and raw materials | 4 | 14% |
| Portland cement — raw materials and compounds | 2 | 7% |
| Concept | PYQs | Share |
|---|---|---|
| Paint ingredients and their roles | 3 | 11% |
| Emulsion paint additives — true/false facts | 1 | 4% |
| Concept | PYQs | Share |
|---|---|---|
| Plaster of Paris, borax and soft soap | 3 | 11% |
| Common alloys and their composition | 1 | 4% |
| Raw materials of Portland cement | 1 | 4% |
Formula & revision sheet
0 formulas · 12 reference tables · 19 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 12 reference tables · 19 gotchas across all subtopics — the exam-eve cheat-sheet
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
Reference tables (2)
Which nutrient each fertilizer supplies6 rows
| Fertilizer | Nutrient supplied | Note |
|---|---|---|
| Urea | Nitrogen (N) | ≈ 46% N — highest-N solid fertilizer Urea is a NITROGEN fertilizer, not a phosphorus one. |
| Ammonium nitrate | Nitrogen (N) | Common N fertilizer |
| Ammonium sulphate | Nitrogen (N) | Common N fertilizer |
| Superphosphate of lime | Phosphorus (P) | Made from rock phosphate + H₂SO₄ |
| Muriate of potash (KCl) | Potassium (K) | Main K source |
| Ammonium sulphide ((NH₄)₂S) | None — not a fertilizer | A lab reagent Ammonium SULPHIDE is the odd one out — it is NOT used as a fertilizer (sulphate, nitrate and phosphate of ammonium all are). |
How superphosphate and nitrolim are made2 rows
| Fertilizer | Made from | Key fact |
|---|---|---|
| Superphosphate of lime | Calcium phosphate + sulphuric acid | Makes phosphate soluble Superphosphate = rock phosphate (calcium phosphate) treated with H₂SO₄. |
| Nitrolim (calcium cyanamide) | Calcium carbide (CaC₂) + nitrogen | Decomposes to ammonia in soil Nitrolim supplies nitrogen only, is inorganic, and is NOT an NPK fertilizer. |
Watch out for (3)
- Urea = nitrogen, never phosphorus→ Which nutrient each fertilizer supplies
- Ammonium sulphide is not a fertilizer→ Which nutrient each fertilizer supplies
- Nitrolim is N-only and inorganic→ How superphosphate and nitrolim are made
Reference tables (2)
Glass — nature and raw materials5 rows
| Aspect | Glass fact | Note |
|---|---|---|
| Physical nature | Amorphous, non-crystalline solid | Supercooled liquid; no definite melting point Glass is a non-crystalline amorphous solid — a supercooled liquid. |
| Source of silica | Sand (SiO₂) | The silica-providing raw material Sand is the source of silica in glass-making. |
| Other raw materials | Soda ash, limestone, borax | Borax → borosilicate (pyrex) |
| NOT a glass material | Gypsum (CaSO₄·2H₂O) | Belongs to cement/plaster, not glass Gypsum is the trap option — it is NOT used in making glass. |
| Pyrex vs soda glass | Pyrex is harder | Pyrex has boron oxide; heat-resistant 'Soda glass is harder than pyrex' is FALSE — pyrex (borosilicate) is the harder, more heat-resistant one. |
Portland cement — raw materials and compounds6 rows
| Aspect | Cement fact | Note |
|---|---|---|
| Raw materials | Lime, silica, alumina | + a little iron oxide Essential constituents of Portland cement: silica, alumina, lime. |
| Alite | 3CaO·SiO₂ | Tricalcium silicate |
| Belite | 2CaO·SiO₂ | Dicalcium silicate |
| Aluminate | 3CaO·Al₂O₃ | Tricalcium aluminate |
| NOT in cement | 4CaO·SiO₂ | No such silicate; only 3:1 and 2:1 4CaO·SiO₂ is the trap — it is NOT a standard cement compound. |
| Setting regulator | Gypsum (small amount) | Slows the setting time |
Watch out for (3)
- Pyrex is harder than soda glass→ Glass — nature and raw materials
- Gypsum is the glass trap→ Glass — nature and raw materials
- 4CaO·SiO₂ does not exist in cement→ Portland cement — raw materials and compounds
Reference tables (2)
Paint ingredients and their roles6 rows
| Role in paint | What it does | Correct example |
|---|---|---|
| Pigment | Colour + opacity | Titanium dioxide (TiO₂) TiO₂ is the standard white pigment; phthalocyanine is a blue/green pigment. |
| Binder (film-former) | Holds pigment, forms the film | Silicones (also resins / drying oils) Silicones are the binder; TiO₂, novolac and phthalocyanine in that question are pigment/resin distractors. |
| Thinner (solvent) | Thins the paint | Turpentine |
| Drier | Accelerates drying (oxidation) | Metal naphthenates Naphthenates are DRIERS, not thinners. Turpentine is the thinner. |
| Anti-skinning agent | Prevents skin in storage | Polyhydroxy phenol Anti-skinning agent = polyhydroxy phenol — not gelatin, pyridine or NMP. |
| Antifoaming agent | Stops foam in emulsion paint | Pine oil |
Emulsion paint additives — true/false facts3 rows
| Statement about emulsion paint | True or false | Why |
|---|---|---|
| Pine oil is used as antifoaming agent | True | Pine oil controls foam |
| Protective colloids decrease stability | False | They INCREASE stability Protective colloids stabilise the emulsion — they increase, not decrease, stability. |
| Oxidizable-oil driers accelerate drying | True | Oxidation speeds film formation |
Watch out for (4)
- Turpentine is the thinner; naphthenates are driers→ Paint ingredients and their roles
- Binder ≠ pigment→ Paint ingredients and their roles
- Anti-skinning agent = polyhydroxy phenol→ Paint ingredients and their roles
- Protective colloids INCREASE stability→ Emulsion paint additives — true/false facts
Reference tables (3)
Common alloys and their composition5 rows
| Alloy | Composition | Use |
|---|---|---|
| Solder | Lead (Pb) + tin (Sn) | Joining/soldering metals Solder is an alloy of lead and tin (Pb + Sn). |
| Brass | Copper + zinc (Cu + Zn) | Fittings, instruments |
| Bronze | Copper + tin (Cu + Sn) | Statues, coins, bearings |
| Steel | Iron + carbon (Fe + C) | Construction, tools |
| Duralumin | Al + Cu + Mg + Mn | Aircraft (light, strong) |
Plaster of Paris, borax and soft soap3 rows
| Substance | Formula / composition | Key fact |
|---|---|---|
| Plaster of Paris | CaSO₄·½H₂O | Calcium sulphate hemihydrate; from gypsum Plaster of Paris = CaSO₄·½H₂O (½ water per CaSO₄), not CaSO₄·2H₂O (that is gypsum). |
| Borax | Na, B, O, H (Na₂B₄O₇·10H₂O) | Sodium tetraborate decahydrate Borax contains sodium, boron, oxygen and hydrogen. |
| Soft soap | Potassium soap | Contains potassium (K) Soft soap = potassium salt; HARD soap = sodium salt. |
Raw materials of Portland cement4 rows
| Raw material | Provides | Source |
|---|---|---|
| Limestone | Lime (CaO) | Calcium carbonate rock |
| Clay / sand | Silica (SiO₂) | Clay, sand |
| Clay | Alumina (Al₂O₃) | Aluminosilicate clay |
| Iron ore + gypsum | Iron oxide; setting control | Added in small amounts Lime, silica and alumina are the essential trio — gypsum is only a setting regulator. |
Watch out for (4)
- Solder = Pb + Sn, brass = Cu + Zn, bronze = Cu + Sn→ Common alloys and their composition
- Soft soap = potassium, hard soap = sodium→ Plaster of Paris, borax and soft soap
- Plaster of Paris is ½ water, gypsum is 2 waters→ Plaster of Paris, borax and soft soap
- Lime + silica + alumina is the trio→ Raw materials of Portland cement