Science & Technology
Chemistry in Everyday Life
Common Chemicals and Materials
Chemicals in daily use for CGPSC: plastics and polymers, fertilisers, cement and glass, fuels, fire extinguishers, and a table of common chemical names.
Prerequisites
- Acids, Bases and Salts — gypsum, washing soda and limestone reappear here as industrial raw materials.
- Metals and Non-metals — carbon’s allotropes and the idea of combustion.
- Energy Resources — the wider policy context of fuels.
The Hook: One Day Across Chhattisgarh
Connect
A farmer near Bemetara buys a bag of urea and a bottle of nano urea from the cooperative society. A truck carries cement out of Baloda Bazar. A family in Raipur changes its LPG cylinder, and a CNG auto passes on the road. At the market, a vendor still hands out a thin plastic bag, which has been illegal for years.
What is in each of these products, why does the LPG cylinder smell, why is gypsum added to cement, and why can one plastic be remoulded while another cannot? This page covers the industrial chemicals of daily life, plus the “common name to formula” table that Prelims loves.
Why it matters: Prelims P-I asks chemical names (laughing gas, dry ice, quicklime), components of LPG and CNG, thermoplastics versus thermosets, the nitrogen content of urea and the role of gypsum in cement. Mains P-IV GS-II asks short notes on plastics and the environment, fertiliser use, and clean fuels.
Polymers and Plastics
A polymer (बहुलक) is a very large molecule made by joining many small units called monomers. The process is polymerisation.
| Natural polymers | Synthetic polymers |
|---|---|
| Cellulose (cotton, wood), starch, proteins (silk, wool), natural rubber | Polythene, PVC, nylon, polyester, Bakelite, Teflon |
Thermoplastics vs thermosetting plastics
| Thermoplastic | Thermosetting plastic |
|---|---|
| Softens on heating and can be remoulded repeatedly | Once set, does not soften on heating (it chars) |
| Linear or slightly branched chains | Heavily cross-linked |
| Polythene, PVC, polystyrene, PET, nylon | Bakelite, melamine |
| Bags, bottles, pipes, toys | Electrical switches and handles of pans (Bakelite); unbreakable crockery and fire-resistant uses (melamine) |
Polymers to remember
| Polymer | Monomer / source | Use |
|---|---|---|
| Polythene | Ethene | Carry bags, packaging films |
| PVC (polyvinyl chloride) | Vinyl chloride | Pipes, wire insulation, raincoats |
| Teflon (PTFE) | Tetrafluoroethene | Non-stick cookware coating |
| PET / polyester (Terylene) | Ethylene glycol + terephthalic acid | Bottles, fabrics (blended with cotton or wool) |
| Nylon | Synthetic (polyamide) | Ropes, parachutes, toothbrush bristles, stockings; very strong |
| Bakelite | Phenol + formaldehyde | Switches, plugs, handles |
| Rayon | Regenerated cellulose from wood pulp | “Artificial silk”; semi-synthetic |
| Natural rubber | Polyisoprene (latex of the rubber tree) | Tyres after vulcanisation (heating with sulphur, which cross-links and hardens it) |
| Neoprene | Synthetic rubber | Conveyor belts, gaskets, hoses |
Biodegradable polymers: PHBV (poly-β-hydroxybutyrate-co-β-hydroxyvalerate), nylon-2-nylon-6 and PLA (polylactic acid, from plant starch) are broken down by microbes.
Plastics and the environment
- Most plastics are non-biodegradable and persist for decades; burning them (especially PVC) releases toxic gases such as dioxins.
- Microplastics are fragments smaller than 5 mm, now found in water, soil and food.
- India’s rules (Plastic Waste Management Amendment Rules, 2021): identified single-use plastic items (including polystyrene and expanded polystyrene items) banned from 1 July 2022; minimum thickness of plastic carry bags raised from 50 to 75 microns from 30 September 2021 and to 120 microns from 31 December 2022. Producers, importers and brand owners carry Extended Producer Responsibility (EPR).
- See Environmental Pollution and Waste Management.
Fertilisers (उर्वरक)
| Fertiliser | Nutrient content | Point to remember |
|---|---|---|
| Urea (CO(NH₂)₂) | 46% nitrogen | The highest-nitrogen common solid fertiliser; made from ammonia and CO₂ |
| DAP (diammonium phosphate) | 18% N, 46% P₂O₅ (18-46-0) | Main phosphate fertiliser for sowing |
| MOP (muriate of potash, KCl) | Potassium | India imports almost all its potash |
| SSP (single super phosphate) | Phosphorus (+ sulphur, calcium) | Cheaper phosphate source |
| NPK complexes | Nitrogen, phosphorus, potassium in fixed ratios | e.g. 10-26-26 |
- Ammonia for fertilisers is made by the Haber process (nitrogen + hydrogen over an iron catalyst at high pressure).
- Neem-coated urea: coating with neem oil slows nitrification, so nitrogen is released gradually and less urea is lost or diverted to industry. All domestically produced urea has been neem-coated since 1 September 2015 (imported urea from 1 December 2015).
- Nano urea (liquid): launched by IFFCO in June 2021, described as the world’s first; a 500 ml bottle is marketed as replacing one bag (45 kg) of conventional urea for foliar spraying. Its field efficiency claims are debated in agronomic studies.
- Overuse problem: a skewed N:P:K ratio (too much cheap urea), soil degradation, nitrate in groundwater (linked to “blue baby syndrome”) and eutrophication. Soil Health Cards and balanced fertilisation are the policy answer. See Agricultural Science and Agricultural Economy.
Cement and Glass
Cement
- Portland cement was patented by Joseph Aspdin in England in 1824 (named after Portland stone, which set concrete resembled).
- Raw materials: limestone (calcium carbonate) + clay (silica, alumina), heated in a kiln to form clinker, then ground.
- Gypsum (2–3%) is added while grinding to slow down the setting of cement.
- Concrete = cement + sand + gravel + water; RCC (reinforced cement concrete) has steel bars inside for tensile strength.
- Portland Pozzolana Cement (PPC) uses fly ash from thermal power plants, which turns a waste into a resource.
Chhattisgarh angle: the cement belt
Rich limestone deposits make Baloda Bazar–Bhatapara the state’s cement hub, with large plants of several major cement companies around Hirmi, Rawan and Sonadih. Fly ash from the coal power plants of Korba and Raigarh can go into PPC and fly-ash bricks, an example of industrial symbiosis. See Minerals, Energy and Industries.
Glass
- Glass is an amorphous solid (sometimes called a supercooled liquid): it has no regular crystal structure.
- Soda-lime glass (windows, bottles) = sand (silica) + sodium carbonate (soda ash) + limestone, melted together.
- Borosilicate glass (Pyrex) resists sudden temperature changes; used for laboratory ware and ovenware.
- Lead crystal glass has high brilliance (decorative glassware).
- Colours come from metal oxides, e.g. cobalt oxide gives blue, chromium oxide gives green.
- Photochromic glass (sunglasses that darken in sunlight) contains silver halide.
- Optical fibres are made of very pure silica glass.
Fuels and Combustion
Calorific value
Calorific value is the heat released by burning 1 kg of a fuel completely, measured in kJ/kg.
| Fuel | Calorific value (approx., kJ/kg) |
|---|---|
| Cow-dung cake | 6,000–8,000 |
| Wood | 17,000–22,000 |
| Coal | 25,000–33,000 |
| Petrol, diesel, kerosene | about 45,000 |
| Biogas | 35,000–40,000 |
| Methane / CNG | about 50,000 |
| LPG | about 55,000 |
| Hydrogen | about 1,50,000 (highest) |
Textbook (NCERT Class 8) values; they vary with fuel quality.
Gaseous fuels
| Fuel | Main component | Point to remember |
|---|---|---|
| LPG | Butane and propane | Odourless by nature; ethyl mercaptan is added so leaks can be smelled |
| CNG | Methane (compressed) | Cleaner than petrol and diesel; used in city transport |
| PNG | Methane (piped natural gas) | Kitchen supply by pipeline |
| Biogas | Methane (plus CO₂) | From anaerobic digestion of dung and waste (gobar gas) |
| Marsh gas | Methane | From decaying vegetation in marshes and paddy fields |
| Water gas | CO + H₂ | Industrial fuel |
| Producer gas | CO + N₂ | Industrial fuel |
Petrol, diesel and cleaner fuels
- Knocking is the premature, uncontrolled ignition of fuel in a petrol engine. Octane number measures a petrol’s resistance to knocking: iso-octane = 100, n-heptane = 0. Higher octane = better anti-knock quality.
- Cetane number measures the ignition quality of diesel.
- Tetraethyl lead (TEL) was once added as an anti-knock agent; leaded petrol was phased out in India around 2000 because lead is a neurotoxin and poisons catalytic converters.
- Bharat Stage VI emission norms apply nationwide from 1 April 2020 (India moved directly from BS-IV, skipping BS-V); BS-VI fuel has very low sulphur.
- Ethanol blending: the target of 20% ethanol in petrol (E20) was advanced from 2030 to 2025; E20 petrol went on sale at selected outlets from 2023. Ethanol is made from sugarcane molasses, cane juice and grains (including surplus rice and maize).
- Green hydrogen: the National Green Hydrogen Mission (approved January 2023) targets about 5 million tonnes of green hydrogen production a year by 2030.
Fire and fire extinguishers
- The fire triangle: fuel + heat (ignition temperature) + oxygen. Removing any one puts a fire out.
- Water cools a fire below ignition temperature, but must not be used on oil or petrol fires (oil floats and spreads) or electrical fires (water conducts).
- Carbon dioxide extinguishers are best for electrical and oil fires: CO₂ is heavier than air, blankets the fire and cuts off oxygen, cools it, and leaves no residue.
- Soda-acid extinguisher: sodium hydrogencarbonate + sulphuric acid release CO₂ that forces out a jet of water.
- Foam extinguishers smother oil fires.
Common Names, Chemical Names and Formulas
| Common name | Chemical name | Formula | Use / note |
|---|---|---|---|
| Quicklime (चूना) | Calcium oxide | CaO | Cement, whitewash (with water) |
| Slaked lime | Calcium hydroxide | Ca(OH)₂ | Whitewash; lime water; bleaching powder |
| Limestone, chalk, marble | Calcium carbonate | CaCO₃ | Cement, construction |
| Gypsum | Calcium sulphate dihydrate | CaSO₄·2H₂O | Cement, POP, alkaline soils |
| Plaster of Paris | Calcium sulphate hemihydrate | CaSO₄·½H₂O | Casts, statues |
| Bleaching powder | Calcium oxychloride | CaOCl₂ | Disinfecting water |
| Baking soda | Sodium hydrogencarbonate | NaHCO₃ | Baking, antacid |
| Washing soda | Sodium carbonate decahydrate | Na₂CO₃·10H₂O | Cleaning, hard water |
| Caustic soda | Sodium hydroxide | NaOH | Soap, paper |
| Caustic potash | Potassium hydroxide | KOH | Soft soaps |
| Common salt | Sodium chloride | NaCl | Food, chlor-alkali |
| Blue vitriol (नीला थोथा) | Copper sulphate pentahydrate | CuSO₄·5H₂O | Fungicide (Bordeaux mixture) |
| Green vitriol (हरा कसीस) | Ferrous sulphate heptahydrate | FeSO₄·7H₂O | Iron supplement, ink |
| White vitriol | Zinc sulphate heptahydrate | ZnSO₄·7H₂O | Zinc fertiliser for paddy (khaira disease) |
| Oil of vitriol | Sulphuric acid | H₂SO₄ | “King of chemicals” |
| Muriatic acid | Hydrochloric acid | HCl | Cleaning; stomach acid |
| Potash alum (फिटकरी) | Potassium aluminium sulphate | K₂SO₄·Al₂(SO₄)₃·24H₂O | Water purification (coagulation), after-shave antiseptic |
| Lunar caustic | Silver nitrate | AgNO₃ | Main chemical in election indelible ink |
| Hypo | Sodium thiosulphate | Na₂S₂O₃·5H₂O | Photographic fixer |
| Sal ammoniac (नौसादर) | Ammonium chloride | NH₄Cl | Dry cells, soldering flux |
| Saltpetre (शोरा) | Potassium nitrate | KNO₃ | Gunpowder, fertiliser |
| Chile saltpetre | Sodium nitrate | NaNO₃ | Fertiliser |
| Laughing gas | Nitrous oxide | N₂O | Anaesthetic |
| Dry ice | Solid carbon dioxide | CO₂ (s) | Refrigerant; sublimes without melting |
| Heavy water | Deuterium oxide | D₂O | Moderator in nuclear reactors |
| Marsh gas | Methane | CH₄ | Biogas, CNG |
| Philosopher’s wool / Chinese white | Zinc oxide | ZnO | Ointments, paints, sunscreens |
| Red lead | Lead tetroxide | Pb₃O₄ | Anti-rust primer paint; sometimes found in cheap sindoor (toxic) |
| Aqua regia | Conc. HCl + conc. HNO₃ (3:1) | — | Dissolves gold and platinum |
Indelible ink
The voter’s ink used in Indian elections has silver nitrate as its key ingredient; silver nitrate reacts with skin and darkens on exposure to light. It is made by Mysore Paints and Varnish Ltd (Karnataka), the sole authorised supplier, using a formula developed with the National Physical Laboratory; it was first used in the 1962 general election.
Hazardous Chemicals: Lessons for Administrators
| Case / chemical | What happened | Lesson |
|---|---|---|
| Bhopal gas tragedy (night of 2–3 December 1984) | Leak of methyl isocyanate (MIC) from the Union Carbide pesticide plant in Bhopal (then in undivided Madhya Pradesh, which included Chhattisgarh) | Industrial safety, siting of hazardous units, disaster preparedness; led to the Environment (Protection) Act, 1986 and later the Public Liability Insurance Act, 1991 |
| Arsenic in groundwater | Villages of the Ambagarh Chowki block (then in Rajnandgaon district), with Kaudikasa the worst affected; the arsenic is geogenic, linked to the Kotri–Dongargarh rift zone | Test water sources, supply safe piped water |
| Lead | Old paints, leaded petrol, battery recycling, some sindoor and cosmetics | Neurotoxic, especially in children |
| Mercury | Thermometers, mercury-cell industries; Minamata disease (Japan) | India is a party to the Minamata Convention on Mercury |
| Asbestos | Old roofing sheets, brake linings | Lung disease (asbestosis), cancer |
Memory Tricks
Thermosets are 'BM' — they Become More rigid
Bakelite and Melamine are thermosetting: heat makes them Burn, not Melt. Everything else common (polythene, PVC, PET, nylon, polystyrene) is thermoplastic.
Urea 46, DAP 18-46
Urea carries 46% N; DAP carries 46% P₂O₅ with 18% N. “46 appears in both; urea puts it in N, DAP puts it in P.”
Vitriols by colour
Blue = Cupper (CuSO₄) · Green = Ferrous (FeSO₄) · White = Zn (ZnSO₄) · Oil = H₂SO₄.
LPG smells because we make it smell
LPG has Butane-Propane, and a Mercaptan for the nose: “Let Better People Mind leaks.”
Don’t Confuse
| This | vs | That |
|---|---|---|
| Quicklime CaO | vs | Slaked lime Ca(OH)₂ vs limestone CaCO₃ |
| Thermoplastic (remouldable) | vs | Thermoset (Bakelite, melamine) |
| Rayon (semi-synthetic, from cellulose) | vs | Nylon (fully synthetic) |
| LPG — butane + propane | vs | CNG — methane |
| Octane number — petrol | vs | Cetane number — diesel |
| Dry ice — solid CO₂ | vs | Heavy water — D₂O |
| Laughing gas N₂O | vs | Nitric oxide NO (pollutant) |
| Gypsum in cement — slows setting | vs | Gypsum in soil — reclaims alkaline land |
Common Mistakes
MCQ traps
- “LPG’s smell is its natural odour.” LPG is odourless; ethyl mercaptan is added.
- “LPG is mainly methane.” That is CNG. LPG is butane and propane.
- “Water can put out any fire.” Not oil or electrical fires; use CO₂ or foam.
- “Gypsum makes cement set faster.” It slows setting.
- “Nylon is a natural fibre.” It is fully synthetic; rayon is the semi-synthetic one from cellulose.
- “Dry ice melts into water.” It sublimes directly into CO₂ gas.
- “Hydrogen has a low calorific value.” It has the highest among common fuels.
- “Neem coating increases the nitrogen content of urea.” It does not; it slows the release (nitrification) of nitrogen.
Practice
All questions below are original practice questions written in CGPSC style. They are not previous-year questions.
Level 1: Foundation
- The substance added to LPG so that a leak can be detected by smell is ______.
- ______ is added to cement clinker to slow down its setting.
- Urea contains about ______% nitrogen.
Answers
- Ethyl mercaptan.
- Gypsum.
- 46%.
Level 2: Prelims MCQs
Q1. Consider the following statements:
- Bakelite and melamine are thermosetting plastics.
- PVC softens on heating and can be remoulded.
- Rayon is a fully synthetic fibre made from petroleum.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 2 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(b) 1 and 2 only. Bakelite and melamine are cross-linked thermosets; PVC is a thermoplastic. Rayon is semi-synthetic, made from regenerated cellulose (wood pulp), so statement 3 is wrong.
Q2. Match List I (Common name) with List II (Chemical):
| List I | List II |
|---|---|
| A. Laughing gas | 1. Solid carbon dioxide |
| B. Dry ice | 2. Silver nitrate |
| C. Lunar caustic | 3. Nitrous oxide |
| D. Blue vitriol | 4. Copper sulphate |
- (a) A-1, B-3, C-2, D-4
- (b) A-3, B-1, C-4, D-2
- (c) A-3, B-1, C-2, D-4
- (d) A-2, B-1, C-3, D-4
Answer and explanation
(c) A-3, B-1, C-2, D-4. Laughing gas is N₂O, an anaesthetic. Dry ice is solid CO₂. Lunar caustic is silver nitrate, the key chemical in election ink. Blue vitriol is CuSO₄·5H₂O.
Q3. Which type of fire extinguisher is most suitable for a fire in an electrical panel?
- (a) Water
- (b) Carbon dioxide
- (c) Soda-acid
- (d) Sand mixed with water
Answer and explanation
(b) Carbon dioxide. CO₂ does not conduct electricity, is heavier than air so it blankets the fire, and leaves no residue on equipment. Water-based extinguishers (including soda-acid, which throws a jet of water) risk electric shock.
Q4. Which of the following fuels has the highest calorific value?
- (a) LPG
- (b) CNG
- (c) Petrol
- (d) Hydrogen
Answer and explanation
(d) Hydrogen, at about 1,50,000 kJ/kg, roughly three times LPG (about 55,000 kJ/kg). Its drawbacks are storage and transport, not energy content. This is one reason for the National Green Hydrogen Mission.
Q5. Consider the following statements about fertilisers in India:
- All urea produced in India has been neem-coated since 2015.
- Neem coating increases the nitrogen content of urea above 46%.
- Nano urea liquid was launched by IFFCO in 2021.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(c) 1 and 3 only. Domestic urea has been 100% neem-coated since 1 September 2015, and IFFCO launched nano urea in June 2021. Neem coating does not raise nitrogen content; it slows nitrification so nitrogen is released gradually and is harder to divert to non-farm use.
Level 3: Mains Answer Writing
Q1. (60 words) Distinguish between thermoplastics and thermosetting plastics with examples.
Model answer outline
- Thermoplastics: linear or lightly branched chains; soften on heating and can be remoulded; recyclable; e.g. polythene, PVC, PET, polystyrene, nylon.
- Thermosets: heavily cross-linked; set permanently and char rather than melt; heat- and electricity-resistant; e.g. Bakelite (switches), melamine (crockery).
- Close: recyclability makes thermoplastics central to plastic waste management and EPR.
Q2. (150–200 words) “Plastics are a boon in use but a bane in disposal.” Discuss with reference to India’s plastic waste management framework.
Model answer outline
- Intro: Plastics are cheap, light, durable polymers; the same durability makes them persist in the environment.
- Boon: packaging that reduces food waste, medical disposables, PVC pipes for drinking water, lightweight vehicle parts, insulation.
- Bane: non-biodegradable; clogged drains and urban flooding; cattle deaths; microplastics (below 5 mm) in water and food; toxic emissions when burnt.
- Framework: Plastic Waste Management Rules, 2016 and amendments; ban on identified single-use plastics from 1 July 2022; carry bags at least 120 microns from 31 December 2022; Extended Producer Responsibility; Swachh Bharat Mission waste segregation.
- Chhattisgarh angle: door-to-door segregated collection by women’s groups in urban local bodies and the use of non-recyclable plastic in road building and cement kilns (co-processing).
- Way forward: enforcement against illegal thin bags, biodegradable alternatives (PLA, PHBV), deposit-refund schemes, behaviour change.
- Conclusion: the goal is not to abolish plastic but to close the loop from design to disposal.
Quick Revision Table
| Fact | Detail |
|---|---|
| Thermosets | Bakelite (phenol + formaldehyde), melamine |
| Teflon | PTFE; non-stick |
| Vulcanisation | Rubber + sulphur |
| Rayon | Semi-synthetic, from cellulose |
| Biodegradable polymers | PHBV, nylon-2-nylon-6, PLA |
| SUP ban | 1 July 2022; carry bags 120 microns from 31 Dec 2022 |
| Urea | 46% N; 100% neem-coated since 2015 |
| DAP | 18-46-0 |
| Nano urea | IFFCO, June 2021 |
| Haber process | Ammonia; iron catalyst |
| Portland cement | Aspdin, 1824; limestone + clay; gypsum slows setting |
| Soda-lime glass | Sand + soda ash + limestone |
| Photochromic glass | Silver halide |
| LPG / CNG | Butane + propane (ethyl mercaptan) / methane |
| Highest calorific value | Hydrogen |
| Octane / cetane | Petrol / diesel |
| BS-VI | Nationwide from 1 April 2020 |
| Electrical fire | CO₂ extinguisher |
| Dry ice / laughing gas / heavy water | CO₂ (s) / N₂O / D₂O |
| Election ink | Silver nitrate; Mysore Paints and Varnish Ltd |
| Bhopal 1984 | Methyl isocyanate |
Key Takeaways
Key Takeaways
- Thermoplastics remould on heating; thermosets (Bakelite, melamine) do not. India banned identified single-use plastics from 1 July 2022.
- Urea = 46% N, neem-coated since 2015; nano urea came in 2021; balanced NPK use protects soil and groundwater.
- Gypsum slows cement setting; Baloda Bazar is Chhattisgarh’s cement hub; fly ash from Korba can go into PPC.
- LPG = butane + propane with an added odorant; CNG = methane; hydrogen has the highest calorific value; octane for petrol, cetane for diesel.
- Learn the common-name table (vitriols, limes, sodas, gases) and the hazardous-chemical cases (Bhopal MIC, arsenic in Ambagarh Chowki).
What’s Next
- Chemistry in Everyday Life — Quick Revision — the whole chapter on one page
- Energy Resources — fuels, green hydrogen and renewables in depth
- Environmental Pollution and Waste Management — plastic and hazardous waste rules
- Agricultural Science — fertilisers, biofertilisers and soil health
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