Chemistry in Everyday Life & Important Compounds

Brass (solid solution/alloy), salt water (liquid), air (gaseous solution).

Only if it has free ions. Salt water conducts; pure distilled water does not.

Limestone (CaCO₃). Gypsum is added only in a small amount at the end to control setting time.

Tetraethyllead (TEL), an anti-knock agent — now phased out for being toxic.

Vitamin D, an antidepressant, and an antihistamine — the usual distractors in contraceptive-pill questions.

Peroxyacetyl nitrate (PAN) — a secondary pollutant of photochemical smog and a lachrymator.

A solution is a homogeneous (uniform) mixture; it looks and tastes the same throughout.

Solute + Solvent = Solution; solute dissolves, solvent does the dissolving.

A saturated solution holds the maximum solute possible at that temperature; extra settles out.

Concentration = amount of solute per unit volume or mass; tells how strong a solution is.

pH scale runs 0-14: below 7 acidic, exactly 7 neutral (pure water), above 7 basic.

Nature

Acidic

Example

Lemon, vinegar

Nature

Neutral

Example

Pure water

Nature

Basic/Alkaline

Example

Soap, baking soda

Solutions, Concentration & pH

Properties that depend only on the NUMBER of solute particles, not their nature — boiling point elevation and freezing point depression.

It lowers the freezing point of water, melting the ice.

It LOWERS the mixture's boiling point, because the added liquid is more volatile and raises the vapour pressure. Salt, a non-volatile solute, does the opposite.

No. It speeds evaporation of sweat, which carries heat away from the skin.

A pressure cooker traps steam, raises internal pressure, so water boils above 100 degrees C and cooks faster.

An ideal solution obeys Raoult's law fully; its heat and volume change on mixing are zero.

The sodium or potassium salt of a long-chain fatty acid (stearic, oleic, palmitic). Potassium soaps (from KOH) are softer on skin than sodium soaps.

Heating fat or oil with NaOH to give soap plus glycerol.

It has a hydrophilic (water-loving) head and a hydrophobic (oil-loving) tail. The tails trap an oil droplet forming a micelle, which floats dirt away and makes water look cloudy.

Ca/Mg salts form sticky scum and poor lather. Synthetic detergents lather even in hard and cold water — they are anionic, cationic or non-ionic.

Quicklime = CaO, made by heating limestone (CaCO₃ → CaO + CO₂). Adding water gives slaked lime, Ca(OH)₂, with much heat.

Soaps & Detergents

Addition: monomers add on with nothing eliminated (polythene). Condensation: monomers join and eject a small molecule like water.

Polymerisation using two different monomers — e.g. buna-S from butadiene and styrene.

Teflon (PTFE) coats non-stick cookware. Polycarbonate (Lexan) is used in CDs, DVDs and helmets.

A polymer is a giant molecule made of many small repeating units called monomers.

Natural rubber is a polymer of isoprene (2-methyl-1,3- butadiene).

Thermoplastics (PVC, polythene) soften and re-mould on heating; thermosetting plastics (bakelite, melamine) set permanently.

Behaviour on heating

Softens, re-mouldable

Examples

PVC, Polythene

Behaviour on heating

Sets permanently

Examples

Bakelite, Melamine

A synthetic aramid fibre from DuPont, about five times stronger than steel per unit weight — used in bullet-proof jackets and helmets. Developed by Stephanie Kwolek in 1965. Boron fibres are also used in vests.

Rayon — regenerated cellulose made from wood pulp. NOT acrylic, and NOT modified starch.

Acrylic is a synthetic fibre resembling wool ('synthetic wool'), not made from cotton. Cotton is a natural plant fibre, good for summer as it absorbs sweat.

PHBV is a biodegradable polymer for eco-friendly packaging, surgical sutures and drug release. Polyblend mixes recycled plastic powder with bitumen for longer-lasting, water-repellent roads.

Linen — flax plant · Coir — coconut husk · Mohair — Angora goat · Down — feathers of duck and geese.

AgBr is light-sensitive and used in photographic films. AgI is used for cloud seeding to make artificial rain.

Specialised synthetic rubber · synthetic sweetener (~200× sweeter than sugar) · hormone · regenerated cellulose, NOT modified starch.

Type

Synthetic

Key use

Bullet-proof gear

Type

Semi-synthetic

Key use

Artificial silk

Type

Synthetic

Key use

Wool-like clothing

Type

Natural

Key use

Summer clothing

Graphite, not diamond. Diamond is harder but metastable.

Diamond: 3D tetrahedral lattice, hardest natural substance, an insulator. Graphite: flat layers, soft and slippery, and the only non-metal that conducts electricity well.

Fullerene (C-60) is a football-shaped molecule; graphene is a single sheet of carbon atoms, a nanostructure (not an alloy or isotope). Stacked graphene layers make graphite.

A tiny slice of graphite (pure carbon). LGDs are made by HPHT or CVD; moissanite, white sapphire and cubic zirconia are only simulants.

Charcoal, coke and lamp black — non-crystalline forms.

Kevlar (1965) → Fullerene (1985) → Graphene (2004) → Black gold (petroleum) — order 4-2-3-1.

Allotropes are different physical forms of the same element; carbon has many.

Diamond is the hardest natural substance; each carbon bonds to four others in 3D.

Lab-grown diamonds (LGDs) use a tiny diamond seed to start crystal growth.

Structure

3D tetrahedral

Property

Hardest, insulator

Structure

Flat layers

Property

Soft, conducts

Structure

Spherical C-60

Property

Molecular form

A homogeneous mix of a metal with other metals or non-metals. Brass = copper + zinc, bronze = copper + tin, steel = iron + carbon.

Copper + nickel and silver + copper — common distractors against brass and bronze.

It is soft and highly reactive — it would react with air and moisture. It is also a good conductor and can be cut with a knife.

Galvanisation coats iron with zinc to prevent rusting. But the zinc coating reacts with oil's free fatty acids, forming toxic compounds and causing rancidity.

Tarnishing — H₂S in the atmosphere forms a black coating of silver sulphide (Ag₂S).

Bauxite — aluminium · Cinnabar — mercury · Calamine — zinc · Galena — lead · Limonite — iron (with hematite and magnetite).

Corundum (Al₂O₃) and cryolite (Na₃AlF₆). Cryolite is the flux in the Hall-Héroult process; corundum's varieties are ruby and sapphire.

Smelting: heat ore with a reducing agent (coke) to get molten metal. Roasting: heat sulphide ore in excess air. Calcination: heat carbonate ore in limited air. Froth flotation: only ore concentration, not extraction.

Gold, silver, platinum and the platinum group — found in pure (native) form in nature. Uranium and lead are NOT noble metals.

Sodium — easily cut with a knife. Mercury — liquid at room temperature. Silver — best conductor of electricity. Lead — poor conductor of heat.

Indium tin oxide (ITO) — a transparent conducting oxide combining conductivity with optical transparency.

Cobalt, iron, magnesium, and copper (brass = copper + zinc).

Bauxite is the ore of aluminium; ores are minerals from which metal is profitably extracted.

Composition

Copper + Zinc

Use

Utensils, fittings

Composition

Copper + Tin

Use

Statues, coins

Composition

Iron + Carbon

Use

Construction

Platinum (Pt) — silvery-white lustre, high corrosion resistance, a noble metal with a very high melting point.

The leak of Methyl Isocyanate (MIC) from the Union Carbide pesticide plant on 3 December 1984 — about 40 tonnes escaped.

Carbon, hydrogen, oxygen and nitrogen — CO(NH₂)₂. It was the first organic compound synthesised in a lab and is a high-nitrogen fertilizer.

Cisplatin — a platinum compound used to treat carcinoma. Taxol — an anti-cancer drug. HMX — High Melting Explosive.

Kerosene — a pure hydrocarbon of only carbon and hydrogen. Soil, glass and cement all contain oxygen. Methane and benzene are also oxygen-free.

Fungicide, red ink, artificial rain, rodenticide.

Synthetic fibre, anticancer drug, rodenticide, explosive/propellant.

Nitrochloroform (chloropicrin) — a fumigant, pesticide and tear-gas, not an explosive.

Milk (brief high-temperature heating, not tea) · sea water · potable water through a membrane · proteins, whose weak bonds break.

It is an alkaloid present in tea, coffee and cola — a bitter white crystalline psychoactive stimulant. Lemon water has vitamin C, not caffeine.

Strontium — red · Sodium — yellow · Magnesium — brilliant white · Copper — blue.

Sodium bicarbonate (NaHCO₃) solution and dilute sulphuric acid — they react to release CO₂: 2NaHCO₃ + H₂SO₄ → Na₂SO₄ + H₂O + 2CO₂.

Baking soda is sodium hydrogen carbonate (NaHCO3); used in fire extinguishers and cooking.

Blue Vitriol is copper sulphate (CuSO4.5H2O); used as fungicide and in electroplating.

Identity / Use

NaHCO3, fire extinguisher

Identity / Use

CuSO4, fungicide

Identity / Use

Cancer treatment

Identity / Use

Bhopal tragedy gas

By molecular targets — the biomolecules a drug acts upon (proteins, carbohydrates, lipids, nucleic acids, receptors, enzymes), because drugs sharing a target share a mechanism of action.

Antibacterials (antimicrobials), first used in the 1930s; they block bacterial folate synthesis by inhibiting dihydropteroate synthase.

Analgesics relieve pain · antipyretics reduce fever · antibiotics kill microbes · antacids (baking soda, milk of magnesia) neutralise excess stomach acid.

Potassium dichromate–sulfuric acid. Orange Cr₂O₇²⁻ (Cr⁶⁺) oxidises ethanol and turns green Cr³⁺; the extent of colour change shows blood alcohol concentration.

Synthetic hormones — estrogen and progesterone derivatives. Levonorgestrel mimics progesterone and prevents ovulation.

Chemicals that kill unwanted weeds — e.g. 2,4-D, atrazine and sodium chlorate. Potassium permanganate and bleaching powder are disinfectants, not herbicides.

The most useful classification of medicines is by their action on a particular target (drug-target).

Nitrous oxide (N₂O) — first prepared by Joseph Priestley (1772), used as a dental/medical anaesthetic. Prepared by thermal decomposition of ammonium nitrate.

Chlorine gas, and also ozone (O₃), chlorine dioxide and chloramine. Ozone is a stronger oxidiser than chlorine.

Grey hydrogen — SMR releases CO₂. Brown comes from coal gasification; green from water electrolysis using renewable energy.

By compressing hydrogen gas to 350–700 bar, or as a cryogenic liquid. Storing it as metal hydrides is chemical storage, not physical.

Butane (C₄H₁₀) — stored under pressure as a liquid, it vaporises to a flammable gas when released.

Mercury — pressure is read as the height of a mercury column. Normal adult reading is about 120/80 mm Hg.

LPG is mainly butane (with propane); used as cooking gas.

Oxygen is absent in compounds like hydrocarbons (e.g. methane, benzene).

Europium-doped strontium aluminate (SrAl₂O₄) — phosphorescent, non-toxic, afterglow up to 12 hours.

Carbon dioxide, methane, CFCs, nitrous oxide and water vapour. Oxygen is NOT a greenhouse gas — a common exam trick.

CO₂ — thermal power stations and fossil fuels · CFCs — refrigerants and aerosols (not automobiles) · Methane/nitrous oxide — paddy fields and cattle · SO₂ — brick kilns.

Respirable Suspended Particulate Matter — fine dust below 5–10 micrometres that is inhaled deep into the lungs; mainly from combustion, vehicles and industry.

By sublimation — naphthalene turns straight to vapour and escapes, leaving the non-volatile sand. Crystallisation purifies solids.

CO2 mainly comes from thermal power stations and burning fossil fuels.

CFCs (chlorofluorocarbons) damage the ozone layer and come from refrigerants and aerosols.

Naphthalene sublimes (solid to gas directly), leaving sand behind.

Main source

Thermal power stations

Main source

Refrigerants, aerosols

Main source

Paddy fields, cattle