BharatNotes Acids and Bases in Everyday Life
pH Scale
- pH measures the hydrogen ion concentration in a solution
- Scale runs from 0 to 14: pH < 7 = acidic; pH = 7 = neutral; pH > 7 = basic/alkaline
- A one-unit change in pH represents a 10-fold change in acidity/alkalinity (logarithmic scale)
pH of Common Substances
| Substance | pH | Nature |
|---|---|---|
| Gastric acid (stomach) | 1.0–2.0 | Strongly acidic |
| Lemon juice | 2.0–2.6 | Acidic |
| Vinegar (acetic acid) | 2.5–3.5 | Acidic |
| Black coffee | 5.0 | Mildly acidic |
| Pure water | 7.0 | Neutral |
| Blood | 7.35–7.45 | Slightly alkaline |
| Baking soda (NaHCO₃) | 8.3 | Mildly alkaline |
| Milk of magnesia | 10.5 | Alkaline |
| Household bleach | 11–12 | Strongly alkaline |
Antacids
Antacids work by neutralising excess hydrochloric acid (HCl) in the stomach:
- Milk of Magnesia: Mg(OH)₂ — reacts with HCl to form MgCl₂ + H₂O
- Aluminium hydroxide: Al(OH)₃ — less likely to cause laxative effect than magnesium salts
- Sodium bicarbonate: NaHCO₃ — quick but produces CO₂ gas (causes belching); not recommended for long-term use
- Calcium carbonate: CaCO₃ — fast-acting; however, "acid rebound" can occur
Acid rain: pH < 5.6; caused by SO₂ and NOₓ reacting with atmospheric moisture to form H₂SO₄ and HNO₃
Soaps and Detergents
Saponification — Making Soap
Saponification is the reaction between a fat/oil (triglyceride) and a strong alkali (NaOH or KOH):
- Fat + NaOH → Soap (sodium salt of fatty acid) + Glycerol
- Hard soaps: NaOH + fats → sodium stearate (solid soap)
- Soft soaps: KOH + fats → potassium stearate (liquid soap, shaving cream)
How Soap Works (Micelle Formation)
Soap molecules have two parts:
- Hydrophilic head (ionic, water-loving) — carboxylate end (–COO⁻ Na⁺)
- Hydrophobic tail (non-polar, oil-loving) — long hydrocarbon chain
When soap is added to water and oil, soap molecules arrange themselves into micelles — spherical clusters where hydrophobic tails surround the oil droplet and hydrophilic heads face the water. This suspends the oil in water (emulsification) and allows washing.
Soap vs Synthetic Detergent
| Feature | Soap | Synthetic Detergent |
|---|---|---|
| Chemical nature | Sodium/potassium salt of fatty acid | Sulfonated organic compound |
| Hard water | Forms insoluble scum (calcium/magnesium stearate) — ineffective | Works in hard water (no scum) |
| Sea water | Ineffective | Effective |
| Biodegradability | Readily biodegradable | Many are poorly biodegradable (environmental concern) |
| Cost | Relatively cheaper | More expensive |
| Examples | Dettol bar, Lifebuoy | SLS (Sodium Lauryl Sulfate), surf, Ariel |
Hard water contains Ca²⁺ and Mg²⁺ ions. Soap reacts with these to form precipitates (scum). Synthetic detergents do not form such precipitates.
Environmental concern with detergents: Branched-chain synthetic detergents are not biodegradable and cause foam formation in rivers and eutrophication (due to phosphates used as builders in detergents).
Polymers
A polymer is a large molecule made by joining many repeating small units (monomers) together.
Natural Polymers
| Polymer | Monomer | Source/Example |
|---|---|---|
| Natural rubber | Isoprene (2-methylbutadiene) | Latex from Hevea brasiliensis |
| Cellulose | Glucose | Plant cell walls; cotton (95% cellulose) |
| Starch | Glucose | Food storage in plants; amylose + amylopectin |
| Protein | Amino acids | Silk (fibroin), wool (keratin) |
| Nucleic acids (DNA/RNA) | Nucleotides | Genetic material |
Synthetic Polymers
| Polymer | Monomer | Properties/Uses |
|---|---|---|
| Nylon-6,6 | Hexamethylenediamine + Adipic acid | Strong fibres; stockings, ropes, parachutes |
| Nylon-6 | Caprolactam | Gears, bearings, carpets |
| PET (Polyethylene terephthalate) | Ethylene glycol + Terephthalic acid | Bottles, fibres (Dacron/Terylene) |
| PVC (Polyvinyl chloride) | Vinyl chloride | Pipes, flooring, cables |
| Bakelite | Phenol + Formaldehyde | Thermosetting; electrical insulation, handles |
| Kevlar | PPTA (para-phenylene-terephthalamide) | Bullet-proof vests; 5× stronger than steel |
| Teflon (PTFE) | Tetrafluoroethylene | Non-stick coating; low friction |
| Polystyrene | Styrene | Thermocol packaging, foam |
| HDPE/LDPE | Ethylene | Plastic bags, containers |
Thermoplastic vs Thermosetting
| Feature | Thermoplastic | Thermosetting |
|---|---|---|
| Behaviour on heating | Softens; can be remoulded | Does NOT soften; chars or burns |
| Cross-linking | No cross-links | Extensive cross-linking |
| Recyclability | Recyclable | Not recyclable |
| Examples | PET, PVC, Nylon, Polythene | Bakelite, epoxy resins, Melamine |
Plastics and Environmental Policy
Single-Use Plastics Ban in India
The Environment (Protection) Act, 1986 and the Plastic Waste Management Rules, 2016 (amended 2022) form the legal framework.
Ban on specific single-use plastics from 1 July 2022:
- Plastic sticks for balloons, flags, candy/ice-cream sticks
- Plastic cutlery (plates, cups, glasses, spoons, knives, forks, straws)
- Plastic wrapping/packing films for invitation cards and cigarette packets
- Plastic cups and plates below 100 microns
Extended Producer Responsibility (EPR):
- EPR mandates that producers, importers, and brand owners are responsible for plastic packaging waste after it leaves the consumer
- EPR framework operationalised under Plastic Waste Management (Amendment) Rules, 2022
- Centralised EPR Portal managed by CPCB (Central Pollution Control Board)
- India has recycled 20.7 million tonnes of plastic packaging waste under EPR since 2022 (as reported to Parliament, March 2026)
Cement
Ordinary Portland Cement (OPC)
Raw materials: Limestone (CaCO₃) + Clay (silica, alumina, iron oxide) + Gypsum
Manufacturing process:
- Crushing limestone and clay; mixing in proportions
- Burning in a rotary kiln at ~1450°C → Clinker (calcium silicates, calcium aluminates, calcium aluminoferrite)
- Grinding clinker with gypsum (3–5%) — gypsum controls the setting time
Hydration reaction (setting): Cement + water → calcium silicate hydrate (C-S-H gel) — this gel is responsible for hardness and strength
Types of Cement
| Type | Features | Use |
|---|---|---|
| OPC (Ordinary Portland Cement) | Standard; fast strength gain | General construction |
| PPC (Portland Pozzolana Cement) | Fly ash added (10–35%); slower setting; lower heat of hydration | Mass concrete, dams, marine structures |
| PSC (Portland Slag Cement) | Blast furnace slag added; durable | Coastal and marine structures |
| Rapid Hardening Cement | Finer grinding; gains strength faster | Repair work, precast elements |
| Low Heat Cement | Lower C₃A and C₃S; less heat | Massive dam foundations |
| Sulfate Resistant Cement | Low tricalcium aluminate (C₃A) | Foundations in sulfate-rich soil |
Glass
Glass is an amorphous solid — atoms are arranged randomly (not crystalline).
Types of Glass
| Type | Composition | Properties/Uses |
|---|---|---|
| Soda-lime glass | SiO₂ + Na₂O + CaO | Most common; windows, bottles |
| Borosilicate glass (Pyrex) | SiO₂ + B₂O₃ (13–15%) | Low thermal expansion; lab glassware, cookware |
| Lead crystal glass | SiO₂ + PbO | High refractive index; sparkles; decorative items |
| Tempered glass | Soda-lime; heat-treated | 5× stronger; safety glass; car windows, phone screens |
| Laminated glass | Two panes + PVB interlayer | Windshields; does not shatter on impact |
| Fibre optic glass | Ultra-pure SiO₂ | Total internal reflection; telecommunications |
| Coloured glass | Metal oxide pigments added (e.g., Cr₂O₃ = green, CuO = blue) | Stained glass, traffic signals |
Fertilisers
India is the world's second-largest consumer of fertilisers (after China).
Major Fertilisers
| Fertiliser | Chemical | Nutrient Content | Notes |
|---|---|---|---|
| Urea | CO(NH₂)₂ | 46% N (highest N content) | Most widely used; subsidised by Government of India |
| DAP (Di-Ammonium Phosphate) | (NH₄)₂HPO₄ | 18% N + 46% P₂O₅ | Used as starter fertiliser; imported largely |
| SSP (Single Super Phosphate) | Ca(H₂PO₄)₂ | 16% P₂O₅ | Contains sulfur and calcium |
| MOP (Muriate of Potash) | KCl | 60% K₂O | |
| NPK complexes | Various | Custom N:P:K ratios | 10:26:26, 12:32:16 are common |
Policy Initiatives
Neem-coated urea policy:
- Government mandated 100% neem coating of subsidised urea in 2015
- Neem oil coating slows release of nitrogen; reduces soil pollution; deters pilferage for industrial uses
- Has improved nitrogen use efficiency (NUE) by 10–15%
Nano Urea (IFFCO):
- Developed by IFFCO (Indian Farmers Fertiliser Cooperative)
- Nano Urea (Liquid) contains nitrogen particles of 20–50 nanometres in size embedded in organic matrix
- 4% nitrogen by weight (compared to 46% in conventional urea)
- World's first commercially produced nano urea fertiliser; IFFCO Aonla plant commissioned 21 December 2022
- Advantages: reduces conventional urea use by up to 50%; lower import bill; eco-friendly
- Applied by foliar spray rather than soil application
- Included in India's Fertilizer Control Order (FCO)
Pesticides
Pesticides are chemicals used to kill, repel, or control pests (insects, fungi, weeds, rodents).
Classification by Target Organism
| Type | Target | Examples |
|---|---|---|
| Insecticides | Insects | Malathion, Chlorpyrifos, DDT |
| Fungicides | Fungi | Carbendazim, Mancozeb, Copper sulfate |
| Herbicides | Weeds | Glyphosate, 2,4-D, Atrazine |
| Rodenticides | Rodents | Aluminium phosphide, Zinc phosphide |
| Bactericides | Bacteria | Streptomycin (for fire blight) |
Classification by Chemical Group
| Group | Mechanism | Examples | Concern |
|---|---|---|---|
| Organochlorines | Disrupt nerve conduction | DDT, BHC, Endosulfan | POPs; bioaccumulate in fat; banned/restricted |
| Organophosphates | Inhibit acetylcholinesterase | Malathion, Chlorpyrifos, Monocrotophos | Moderately toxic to mammals |
| Carbamates | Inhibit acetylcholinesterase (reversible) | Carbaryl, Carbofuran | Less persistent than OPs |
| Pyrethroids | Disrupt Na⁺ channels in nerve cells | Cypermethrin, Deltamethrin | Low mammalian toxicity; high fish toxicity |
| Neonicotinoids | Nicotinic acetylcholine receptor agonists | Imidacloprid, Thiamethoxam | Linked to bee colony collapse disorder |
Stockholm Convention (2001) — Persistent Organic Pollutants (POPs)
- Bans or restricts 12 "dirty dozen" chemicals initially (including DDT, Aldrin, Dieldrin, PCBs)
- India ratified Stockholm Convention in 2006
- DDT banned in India for agricultural use; permitted only for vector control (malaria) in limited quantities
Industrial Chemistry — Key Processes
Haber-Bosch Process (Ammonia Synthesis)
- Reaction: N₂ + 3H₂ ⇌ 2NH₃
- Conditions: Temperature 450–500°C, pressure 150–300 atm, iron catalyst with potassium oxide and aluminium oxide as promoters
- Basis of all synthetic nitrogen fertilisers; one of the most important chemical processes in history
- Fritz Haber (discovery) + Carl Bosch (industrialisation) — both received Nobel Prizes
Contact Process (Sulphuric Acid)
- Step 1: S + O₂ → SO₂
- Step 2: 2SO₂ + O₂ ⇌ 2SO₃ (catalyst: V₂O₅/vanadium pentoxide; 400–600°C)
- Step 3: SO₃ + H₂SO₄ → H₂S₂O₇ (oleum) → H₂SO₄
- H₂SO₄ is the most produced industrial chemical; used in fertilisers, batteries, explosives, pharmaceuticals
Chlor-Alkali Process
- Electrolysis of brine (NaCl solution):
- At cathode: 2H₂O + 2e⁻ → H₂ + 2OH⁻
- At anode: 2Cl⁻ → Cl₂ + 2e⁻
- Products: Chlorine (Cl₂), Sodium hydroxide (NaOH), and Hydrogen (H₂)
- Uses: NaOH in paper, soap, textiles; Cl₂ for PVC, water treatment, solvents
Nanomaterials
Nanomaterials have dimensions in the 1–100 nanometre range (1 nm = 10⁻⁹ m). At this scale, materials exhibit unique physical and chemical properties different from their bulk counterparts.
Key Carbon Nanomaterials
| Material | Structure | Properties | Applications |
|---|---|---|---|
| Fullerenes (C₆₀) | Spherical cage of 60 carbon atoms (soccer ball shape) | High stability; can trap molecules | Drug delivery, lubricants |
| Carbon Nanotubes (CNTs) | Rolled graphene sheets; single-wall (SWCNT) or multi-wall (MWCNT) | 100× stronger than steel; excellent conductivity | Composites, electronics, sensors |
| Graphene | Single atomic layer of graphite; hexagonal lattice | Strongest material known; best conductor of electricity at room temperature | Flexible electronics, membranes, batteries |
Nanoparticles in Everyday/Medical Use
| Material | Use |
|---|---|
| Silver nanoparticles (AgNPs) | Antimicrobial coatings in hospital equipment, textiles |
| Gold nanoparticles | Targeted drug delivery; cancer photothermal therapy; diagnostic kits |
| Titanium dioxide (TiO₂) NPs | Sunscreens; self-cleaning glass; photocatalytic degradation of pollutants |
| Iron oxide NPs | MRI contrast agents; targeted cancer therapy |
| Zinc oxide NPs | UV protection; antimicrobial in food packaging |
UPSC relevance: Nano fertilisers (Nano Urea — IFFCO), nano-drug delivery, nanomaterial safety regulations, Mission for Advancement in High-Impact Areas (MAHA) initiative
Green Chemistry
Green Chemistry (also called "sustainable chemistry") is the design of chemical processes and products that reduce or eliminate the use and generation of hazardous substances.
Coined by: Paul Anastas and John Warner (1998 book: Green Chemistry: Theory and Practice)
12 Principles of Green Chemistry (Anastas & Warner, 1998)
| # | Principle | Meaning |
|---|---|---|
| 1 | Prevention | Prevent waste rather than treat/clean up after |
| 2 | Atom Economy | Design reactions to incorporate all starting materials into the final product |
| 3 | Less Hazardous Syntheses | Use/generate substances with little or no toxicity |
| 4 | Safer Chemicals | Design chemical products to have desired function but low toxicity |
| 5 | Safer Solvents & Auxiliaries | Avoid unnecessary solvents; use benign solvents where possible |
| 6 | Design for Energy Efficiency | Minimise energy requirements; use ambient temperature/pressure |
| 7 | Renewable Feedstocks | Use renewable raw materials (biomass) over depleting ones (petroleum) |
| 8 | Reduce Derivatives | Avoid protecting groups/blocking groups — these create waste |
| 9 | Catalysis | Use catalytic reagents (selective, minimal) rather than stoichiometric reagents |
| 10 | Design for Degradation | Products should break down into innocuous products after use |
| 11 | Real-time Analysis | Monitor and control in real-time to prevent pollution |
| 12 | Inherently Safer Chemistry | Use safer forms of substances to minimise accidents (explosion, fire, release) |
Atom economy = (Molecular weight of desired product / Total molecular weight of all products) × 100
Green chemistry in India: National Initiative on Green Chemistry (NIGC) under DST; Green Chemistry Award by Chemical Research Society of India (CRSI)
Dyes and Pigments
| Feature | Dye | Pigment |
|---|---|---|
| Solubility | Soluble in water or organic solvents | Insoluble in the medium |
| Bonding | Chemical bond with substrate | Physical adhesion/entrapment |
| Examples | Indigo, Methyl orange, Azo dyes | Titanium white (TiO₂), Lead red, Ultramarine |
Natural dyes: Indigo (Indigofera tinctoria) — used for millennia; revived in organic textiles Synthetic dyes: Mauveine (William Perkin, 1856) — first synthetic dye; sparked the synthetic dye industry Azo dyes: Largest class of synthetic dyes (~50% of all dyes); contain –N=N– linkage; some are carcinogenic when metabolised
Food colours:
- Permitted in India (FSSAI): Tartrazine (yellow), Sunset Yellow, Carmoisine, Brilliant Blue, etc.
- Banned: Sudan dyes (used in chillies/palm oil — adulterants); Butter Yellow (carcinogenic)
Pharmaceuticals
Active Pharmaceutical Ingredient (API): The biologically active component of a drug that produces the therapeutic effect.
India as API hub:
- India produces ~20% of the world's generic medicines by volume
- India is the largest supplier of generic drugs globally — exports to 200+ countries
- India supplies ~60% of global vaccine demand (SERUM Institute, Bharat Biotech)
- India is the pharmacy of the developing world
- However, India is heavily import-dependent for bulk APIs — ~65–70% of API raw materials (Key Starting Materials, KSMs) imported from China
- PLI scheme for APIs (launched 2020): ₹6,940 crore incentive for domestic API manufacturing in 53 critical APIs across 41 products
Generic drugs vs branded drugs: Generic drugs contain the same API as branded versions but are sold at much lower prices after patent expiry; UPSC-relevant in context of access to medicines
Food Chemistry
FSSAI (Food Safety and Standards Authority of India): Statutory body under the Food Safety and Standards Act, 2006; Ministry of Health and Family Welfare; regulates food additives, labelling, and safety standards.
Common Food Additives
| Category | Function | Examples |
|---|---|---|
| Preservatives | Prevent microbial growth | Sodium benzoate, potassium sorbate, sodium nitrite (in meats) |
| Antioxidants | Prevent oxidation/rancidity | Ascorbic acid (Vitamin C), BHA, BHT, Vitamin E |
| Emulsifiers | Stabilise oil-water mixtures | Lecithin (from soy/egg), mono- and diglycerides |
| Stabilisers/Thickeners | Improve texture | Agar, pectin, carrageenan, guar gum, xanthan gum |
| Artificial sweeteners | Low-calorie sweetness | Saccharin, aspartame, sucralose, stevia |
| Acidity regulators | Control pH | Citric acid, tartaric acid, lactic acid |
| Colours | Visual appeal | Tartrazine (E102), Carmoisine (E122) |
Maillard reaction: Non-enzymatic browning; reaction between amino acids and reducing sugars on heating; responsible for the flavour and colour of bread crust, roasted coffee, seared meat.
Previous Year Questions (PYQs)
Prelims
With reference to carbon nanotubes, which of the following statements is/are correct? (a) They can be used as carriers of drugs and antigens in the human body (b) They can be made into artificial muscles (c) They can be used in the processing of food items Which of the above statements are correct? (UPSC CSP 2020)
With reference to the use of nanomaterials, which one of the following statements is NOT correct? (a) Nanosized zinc oxide is used as a sunscreen lotion ingredient (b) Nano gold is used as a component in automotive catalytic converters (c) Nanosilver is used in water purification (d) Nano titanium dioxide is used as a food preservative (UPSC CSP 2019 — adapted)
Which of the following is NOT a greenhouse gas? (a) Methane (CH₄) (b) Nitrous Oxide (N₂O) (c) Carbon Dioxide (CO₂) (d) Nitrogen (N₂) (UPSC CSP 2016 — adapted)
Nano Urea (Liquid), launched by IFFCO, is primarily made using which technology? (a) Genetic modification of urea-producing bacteria (b) Nanotechnology — nano-sized nitrogen particles encapsulated in organic matrix (c) Microwave synthesis of ammonia (d) Electrolysis of ammonium nitrate (UPSC CSP 2022 — adapted)
Mains
What is Green Chemistry? Discuss any five of its twelve principles and explain how they contribute to sustainable development. (UPSC GS3 2018 — adapted)
India is called the "pharmacy of the world." Examine India's pharmaceutical sector with reference to API production, generic drugs, and the challenges of dependence on Chinese raw materials. (UPSC GS3 2021)
Discuss the environmental concerns associated with synthetic detergents and single-use plastics. What regulatory measures has India taken to address them? (UPSC GS3 2020 — adapted)
Recent Developments (2024–2026)
India's PLI Scheme — Speciality Chemicals and Materials (2024–25)
India's Production Linked Incentive (PLI) scheme expanded to include speciality chemicals, advanced materials, and agrochemicals in 2024–25. India's chemical sector (3rd largest in Asia, 6th globally) saw investments in fluorochemicals, specialty polymers, and pharmaceutical intermediates. The single-use plastic ban enforcement (19 categories banned since July 2022) accelerated development of biodegradable polymer alternatives. CSIR-CRRI's steel slag road demonstrated industrial waste valorisation in construction materials.
UPSC angle: India's speciality chemicals PLI and plastic ban enforcement are the most current industrial chemistry policy developments — relevant for GS3 industrial sector and environment questions.
National Green Hydrogen Mission — Green Chemistry at Scale (2024–25)
India's NGHM (January 2023) operationalised green hydrogen and green ammonia pilot projects in 2024–25. Green ammonia (NH₃) produced via green hydrogen + nitrogen (Haber-Bosch using renewable electricity) is India's pathway to decarbonising nitrogen fertilizer production — replacing fossil fuel-intensive brown ammonia synthesis. This represents the application of industrial process chemistry (Haber-Bosch, electrolysis) to India's fertilizer and energy transition goals.
UPSC angle: Green hydrogen/green ammonia connects industrial process chemistry (Haber-Bosch process, nitrogen chemistry) to India's energy transition and fertilizer policy — one of the strongest science-policy integration examples.
Exam Strategy
For Prelims:
- pH scale: 0–7 acidic, 7 neutral, 7–14 alkaline; blood pH = 7.35–7.45
- Saponification = fat + NaOH → soap + glycerol
- Soap fails in hard water; synthetic detergents work but are poorly biodegradable
- Thermoplastics (recyclable): PET, PVC, Nylon; Thermosetting (not recyclable): Bakelite, Melamine
- Haber-Bosch: N₂ + 3H₂ → 2NH₃; iron catalyst; 450–500°C, 150–300 atm
- Contact process (H₂SO₄): V₂O₅ catalyst
- Chlor-alkali: electrolysis of brine → Cl₂ + NaOH + H₂
- Green Chemistry: 12 principles by Anastas and Warner (1998)
- Nano Urea: IFFCO; 20–50 nm particle size; 4% N content; FCO approved
- Fullerenes (C₆₀), CNTs, Graphene — all carbon nanomaterials; graphene = strongest known material
- FSSAI: Food Safety and Standards Act, 2006; under Ministry of Health
For Mains:
- Link green chemistry to SDG 12 (Responsible Consumption and Production) and India's green manufacturing goals
- EPR for plastics is a strong policy example for environmental governance answers
- India's API dependence on China is a strategic vulnerability — link to Atmanirbhar Bharat and PLI scheme
- Nano fertilisers (Nano Urea) reduce India's urea import bill and subsidy burden — link to fiscal policy
- Food additives and FSSAI regulation: strong example for consumer protection and food security answers
