Glossary
Every technical word in the course and what it means in plain language, with flashcards for practice.
Every technical term in the course, with a plain-language meaning. On every page these words are marked with a dotted underline: hover or tap one to see its meaning. The “Used in” links point to the sections where each term appears.
Ch 1 · Chemical Reactions and EquationsCh 2 · Acids, Bases and SaltsCh 3 · Metals and Non-metalsCh 4 · Carbon and its Compounds
Ch 1 · Chemical Reactions and Equations
| Term | Meaning | Used in |
|---|---|---|
| antioxidant | A substance added to food containing fats and oils to slow down their oxidation (rancidity), e.g. vitamin E. | 1.3 |
| balanced chemical equation | An equation with the same number of atoms of each element on both sides, using the smallest whole-number coefficients, e.g. $\mathrm{2Mg + O_{2} \rightarrow 2MgO}$. | 1.1 1.2 1.3 2.1 |
| chemical reaction | A process in which substances (reactants) change into new substances (products) with different properties, because their atoms are regrouped. | 1.1 1.3 4.3 |
| combination reaction | A reaction in which two or more reactants form a single product, $\mathrm{A + B \rightarrow AB}$, e.g. $\mathrm{CaO + H_{2}O \rightarrow Ca(OH)_{2}}$. | 1.2 |
| corrosion | The slow eating away of a metal by substances around it such as moisture, oxygen, acids or sulphur compounds: iron rusts, silver turns black, copper turns green. | 1.3 2.1 3.1 3.3 |
| decomposition reaction | A reaction in which a single reactant breaks down into two or more simpler products, $\mathrm{AB \rightarrow A + B}$, using energy supplied as heat, light or electricity. | 1.2 |
| displacement reaction | A reaction in which a more reactive element pushes a less reactive one out of its compound, $\mathrm{A + BC \rightarrow AC + B}$, e.g. $\mathrm{Fe + CuSO_{4} \rightarrow FeSO_{4} + Cu}$. | 1.2 2.1 3.1 |
| double displacement reaction | A reaction in which two compounds exchange ions to form two new compounds, $\mathrm{AB + CD \rightarrow AD + CB}$, e.g. $\mathrm{Na_{2}SO_{4} + BaCl_{2} \rightarrow BaSO_{4} + 2NaCl}$. | 1.2 2.1 |
| electrolytic decomposition | Decomposition brought about by passing an electric current, e.g. water splitting into hydrogen and oxygen in the volume ratio 2 : 1. | 1.2 2.3 3.3 |
| endothermic reaction | A reaction that takes in energy from the surroundings, e.g. most decompositions and photosynthesis. | 1.2 |
| exothermic reaction | A reaction that gives out energy (usually heat) to the surroundings, e.g. burning, respiration, quicklime with water. | 1.2 2.1 |
| law of conservation of mass | Mass is neither created nor destroyed in a chemical reaction: in a closed system the total mass of the products equals the total mass of the reactants. | 1.1 1.3 4.3 |
| oxidation | Gain of oxygen or loss of hydrogen by a substance, e.g. $\mathrm{2Cu + O_{2} \rightarrow 2CuO}$. (In Class 11: loss of electrons.) | 1.2 1.3 4.3 4.4 |
| oxidising agent | The substance that brings about oxidation by giving oxygen (or taking hydrogen); it is itself reduced. | 1.3 2.3 3.1 4.3 |
| photolytic decomposition | Decomposition brought about by light, e.g. white silver chloride turning grey in sunlight as silver forms. | 1.2 |
| precipitate | An insoluble solid that separates out of a solution during a reaction, e.g. yellow lead iodide $\mathrm{PbI_{2}}$; given the state symbol (s). | 1.1 1.2 2.1 4.4 |
| precipitation reaction | Any reaction that produces a precipitate (an insoluble solid) from solutions; most are double displacement reactions. | 1.2 |
| product | A new substance formed in a chemical reaction; products are written on the right of the arrow. | 1.1 1.2 1.3 2.1 |
| rancidity | The bad smell and taste of food containing fats and oils after they are oxidised by air; slowed by antioxidants, airtight packing, nitrogen flushing and cold storage. | 1.3 |
| reactant | A substance present at the start of a chemical reaction; reactants are written on the left of the arrow. | 1.1 1.2 1.3 3.3 |
| redox reaction | A reaction in which one substance is oxidised and another is reduced at the same time, e.g. $\mathrm{CuO + H_{2} \rightarrow Cu + H_{2}O}$. | 1.3 3.3 |
| reducing agent | The substance that brings about reduction by taking oxygen (or giving hydrogen); it is itself oxidised, e.g. carbon, hydrogen, carbon monoxide. | 1.3 3.3 |
| reduction | Loss of oxygen or gain of hydrogen by a substance, e.g. $\mathrm{CuO}$ becoming $\mathrm{Cu}$ when heated in hydrogen. (In Class 11: gain of electrons.) | 1.3 3.3 4.3 |
| rust | Reddish-brown, flaky hydrated iron(III) oxide, $\mathrm{Fe_{2}O_{3}\cdot xH_{2}O}$, formed when iron is exposed to both oxygen and water. | 1.1 1.3 3.1 3.3 |
| skeletal equation | A chemical equation with the correct formulas but not yet balanced, e.g. $\mathrm{Mg + O_{2} \rightarrow MgO}$. | 1.1 1.2 |
| state symbol | A label after a formula showing its physical state: (s) solid, (l) liquid, (g) gas, (aq) dissolved in water. | 1.1 1.2 2.1 2.3 |
| thermal decomposition | Decomposition brought about by heating, e.g. $\mathrm{CaCO_{3} \rightarrow CaO + CO_{2}}$ in a lime kiln. | 1.2 |
Ch 2 · Acids, Bases and Salts
| Term | Meaning | Used in |
|---|---|---|
| acid | A substance that tastes sour, turns blue litmus red and, in water, gives hydrogen ions $\mathrm{H^{+}(aq)}$ (hydronium ions), e.g. $\mathrm{HCl}$, $\mathrm{H_{2}SO_{4}}$, citric acid. | 1.1 1.2 1.3 2.1 |
| acid rain | Rain with a pH below 5.6, caused by oxides of sulphur and nitrogen dissolving in rain water to form sulphuric and nitric acids. | 2.1 2.2 |
| acidic oxide | An oxide, usually of a non-metal, that reacts with a base to give a salt and water, e.g. $\mathrm{CO_{2}}$ with lime water. | 2.1 2.2 3.1 |
| alkali | A base that dissolves in water, giving hydroxide ions $\mathrm{OH^{-}(aq)}$, e.g. $\mathrm{NaOH}$, $\mathrm{KOH}$, $\mathrm{Ca(OH)_{2}}$, $\mathrm{NH_{4}OH}$. All alkalis are bases, but not all bases are alkalis. | 2.1 2.3 3.1 3.2 |
| anhydrous | Without water of crystallisation, e.g. white $\mathrm{CuSO_{4}}$, the form left when blue copper sulphate crystals are heated. | 1.3 2.3 |
| antacid | A mild base, such as milk of magnesia or baking soda, taken to neutralise excess acid in the stomach. | 2.1 2.2 2.3 3.2 |
| baking powder | A mixture of baking soda and a mild solid acid such as tartaric acid; it releases carbon dioxide in water and makes cakes and bread rise. | 2.3 |
| baking soda | Sodium hydrogencarbonate $\mathrm{NaHCO_{3}}$, a mild base used in cooking, antacids and fire extinguishers; on heating it gives $\mathrm{Na_{2}CO_{3}}$, water and carbon dioxide. | 1.1 1.2 2.1 2.2 |
| base | A substance that tastes bitter, feels soapy, turns red litmus blue and neutralises an acid to give a salt and water, e.g. $\mathrm{NaOH}$, $\mathrm{CuO}$, $\mathrm{Mg(OH)_{2}}$. | 1.2 2.1 2.2 2.3 |
| basic oxide | An oxide, usually of a metal, that reacts with an acid to give a salt and water, e.g. $\mathrm{CuO + 2HCl \rightarrow CuCl_{2} + H_{2}O}$. | 2.1 3.1 |
| bleaching powder | Calcium oxychloride $\mathrm{CaOCl_{2}}$, made by passing chlorine over dry slaked lime; used for bleaching and for disinfecting drinking water. | 2.3 |
| chlor-alkali process | The electrolysis of brine, giving sodium hydroxide, chlorine (at the anode) and hydrogen (at the cathode): $\mathrm{2NaCl + 2H_{2}O \rightarrow 2NaOH + Cl_{2} + H_{2}}$. | 2.3 |
| dilution | Lowering the concentration of a solution by adding water. Diluting an acid raises its pH towards 7 (never beyond); diluting a base lowers its pH towards 7. | 2.1 2.2 |
| end point | The stage in a neutralisation at which exactly enough base (or acid) has been added to use up the other, shown by the indicator changing colour. | 2.2 |
| gypsum | Hydrated calcium sulphate $\mathrm{CaSO_{4}\cdot 2H_{2}O}$; heating it at 373 K gives plaster of Paris. | 2.3 |
| hydronium ion | The ion $\mathrm{H_{3}O^{+}}$, formed when a hydrogen ion from an acid joins a water molecule: $\mathrm{H^{+} + H_{2}O \rightarrow H_{3}O^{+}}$. | 2.1 2.2 |
| indicator | A substance that shows by a change of colour (or smell) whether a solution is acidic or basic, e.g. litmus, phenolphthalein, methyl orange, turmeric. | 2.1 2.2 2.3 |
| litmus | A natural purple dye from lichens: red in acids, blue in bases. Blue litmus paper turns red in an acid; red litmus paper turns blue in a base. | 2.1 2.2 2.3 3.1 |
| neutralisation | The reaction of an acid with a base to give a salt and water, e.g. $\mathrm{NaOH + HCl \rightarrow NaCl + H_{2}O}$; in ions, $\mathrm{H^{+} + OH^{-} \rightarrow H_{2}O}$. | 1.2 2.1 2.2 2.3 |
| olfactory indicator | An indicator whose smell changes: the smell of onion, vanilla essence or clove oil cannot be detected in a basic solution but stays in an acidic one. | 2.1 |
| pH scale | A scale from 0 to 14 that shows how acidic or basic a solution is: below 7 acidic, 7 neutral, above 7 basic. The lower the pH, the more hydronium ions $\mathrm{H_{3}O^{+}}$ the solution has. | 2.1 2.2 2.3 4.4 |
| phenolphthalein | A synthetic indicator that is colourless in acidic and neutral solutions and pink in basic solutions. | 2.1 2.2 2.3 |
| plaster of Paris | A white powder $\mathrm{CaSO_{4}\cdot\tfrac{1}{2}H_{2}O}$ that sets into hard gypsum when mixed with water; used for casts, toys and smoothing walls. | 2.3 |
| salt | An ionic compound formed when the hydrogen ions of an acid are replaced by a metal (or ammonium) ion, e.g. $\mathrm{NaCl}$, $\mathrm{K_{2}SO_{4}}$, $\mathrm{CuSO_{4}}$; the other product of neutralisation besides water. | 1.1 1.2 1.3 2.1 |
| strong acid | An acid that gives almost all its hydrogen ions to water, e.g. $\mathrm{HCl}$, $\mathrm{H_{2}SO_{4}}$, $\mathrm{HNO_{3}}$. It has a low pH and reacts fast with metals and carbonates. | 2.2 2.3 4.4 |
| strong base | A base that gives almost all its hydroxide ions in water, e.g. $\mathrm{NaOH}$ and $\mathrm{KOH}$. | 2.1 2.2 2.3 |
| universal indicator | A mixture of dyes that shows a different colour at each pH (red for strong acids, green at pH 7, violet for strong bases), so the pH can be read approximately. | 2.2 2.3 |
| washing soda | Hydrated sodium carbonate $\mathrm{Na_{2}CO_{3}\cdot 10H_{2}O}$, a basic salt used in glass, soap and paper industries and to remove hardness of water. | 2.1 2.2 2.3 3.2 |
| water of crystallisation | The fixed number of water molecules that form part of the crystal of a hydrated salt, e.g. 5 in $\mathrm{CuSO_{4}\cdot 5H_{2}O}$. | 1.2 2.3 |
| weak acid | An acid that gives only a few hydrogen ions to water, e.g. ethanoic acid $\mathrm{CH_{3}COOH}$ and carbonic acid $\mathrm{H_{2}CO_{3}}$. | 2.2 2.3 4.4 |
| weak base | A base that gives only a few hydroxide ions in water, e.g. $\mathrm{NH_{4}OH}$ and $\mathrm{Mg(OH)_{2}}$. | 2.1 2.2 2.3 |
Ch 3 · Metals and Non-metals
| Term | Meaning | Used in |
|---|---|---|
| alloy | A homogeneous mixture of two or more metals, or of a metal and a non-metal, e.g. steel, brass, bronze, solder, stainless steel; usually harder and more corrosion-resistant than the main metal. | 1.3 3.3 |
| amphoteric oxide | A metal oxide that reacts with both acids and bases to give salt and water, e.g. $\mathrm{Al_{2}O_{3}}$ and $\mathrm{ZnO}$. | 3.1 |
| anion | A negatively charged ion, formed when an atom (usually a non-metal) gains electrons, e.g. $\mathrm{Cl^{-}}$, $\mathrm{O^{2-}}$. | 3.2 |
| anode | The positive electrode in electrolysis, where negative ions lose electrons (oxidation); in refining, the impure metal dissolves from it. | 2.3 3.1 3.2 3.3 |
| aqua regia | A freshly prepared 3 : 1 mixture of concentrated hydrochloric acid and concentrated nitric acid, able to dissolve gold and platinum. | 3.1 |
| calcination | Heating a carbonate ore strongly in a limited supply of air to convert it into the oxide, e.g. $\mathrm{ZnCO_{3} \rightarrow ZnO + CO_{2}}$. | 3.3 |
| cathode | The negative electrode in electrolysis, where positive ions gain electrons (reduction) and the metal is deposited. | 2.3 3.2 3.3 |
| cation | A positively charged ion, formed when an atom (usually a metal) loses electrons, e.g. $\mathrm{Na^{+}}$, $\mathrm{Mg^{2+}}$. | 3.2 |
| ductile | Able to be drawn out into thin wires, as copper and gold can. | 3.1 |
| electrolytic refining | Purifying a metal by making the impure metal the anode and a strip of pure metal the cathode in a solution of its salt; the pure metal deposits on the cathode and impurities fall as anode mud. | 3.3 |
| formula unit | The simplest ratio of ions in an ionic compound, e.g. $\mathrm{NaCl}$ ($1:1$) or $\mathrm{MgCl_{2}}$ ($1:2$); an ionic crystal has no separate molecules. | 2.3 3.2 |
| galvanisation | Coating iron or steel with a layer of zinc to prevent rusting; zinc, being more reactive, is attacked first even if the coating is scratched. | 1.3 3.1 3.3 |
| gangue | The earthy impurities (sand, soil, rock) mixed with an ore, removed during enrichment. | 3.3 |
| ion | An atom or group of atoms with an electric charge because it has lost or gained electrons, e.g. $\mathrm{Na^{+}}$, $\mathrm{Cl^{-}}$, $\mathrm{O^{2-}}$. | 1.1 1.2 1.3 2.1 |
| ionic bond | The strong electrostatic attraction between oppositely charged ions formed by the transfer of electrons from a metal atom to a non-metal atom. | 3.2 4.1 |
| ionic compound | A compound made of positive and negative ions held together by ionic bonds, e.g. $\mathrm{NaCl}$, $\mathrm{MgO}$; it is a hard, brittle solid with a high melting point that conducts only when molten or dissolved. | 2.3 3.2 4.1 |
| lustre | The shine of a freshly cut or polished metal surface; most metals are lustrous, most non-metals are dull (iodine is a shiny exception). | 3.1 |
| malleable | Able to be hammered or rolled into thin sheets without breaking, as gold, silver and aluminium can. | 3.1 3.2 |
| noble metal | A metal at the bottom of the reactivity series, such as gold, silver or platinum, that hardly reacts with oxygen, water or acids. | 3.1 |
| octet | A full outermost shell: eight electrons (octet), or two for the first shell (duplet). Atoms react to reach this stable noble-gas arrangement. | 3.2 4.1 |
| ore | A mineral from which a metal can be extracted profitably, e.g. haematite $\mathrm{Fe_{2}O_{3}}$, bauxite, cinnabar $\mathrm{HgS}$. | 3.1 3.3 |
| reactivity series | The list of metals in decreasing order of reactivity: K, Na, Ca, Mg, Al, Zn, Fe, Pb, [H], Cu, Hg, Ag, Au. A metal displaces any metal lower in the list from its salt solution. | 1.2 2.1 3.1 3.3 |
| roasting | Heating a sulphide ore strongly in excess air to convert it into the oxide, e.g. $\mathrm{2ZnS + 3O_{2} \rightarrow 2ZnO + 2SO_{2}}$. | 3.3 |
| sonorous | Producing a ringing sound when struck; metals are sonorous, which is why bells are made of metal. | 3.1 |
| thermite reaction | The reaction of a metal oxide with aluminium that gives molten metal and a great deal of heat, e.g. $\mathrm{Fe_{2}O_{3} + 2Al \rightarrow Al_{2}O_{3} + 2Fe}$; used to weld railway tracks. | 1.2 3.3 |
| valence electron | An electron in the outermost shell of an atom; valence electrons decide how the atom reacts. | 3.2 |
Ch 4 · Carbon and its Compounds
| Term | Meaning | Used in |
|---|---|---|
| addition reaction | A reaction in which atoms add across the double or triple bond of an unsaturated compound, e.g. $\mathrm{C_{2}H_{4} + H_{2} \rightarrow C_{2}H_{6}}$. | 4.3 |
| alcohol | A compound containing the hydroxyl group $-\mathrm{OH}$ on a carbon chain, e.g. ethanol; names end in -ol. | 2.1 4.2 4.3 4.4 |
| aldehyde | A compound containing the group $-\mathrm{CHO}$ at the end of a carbon chain, e.g. ethanal; names end in -al. | 4.2 |
| alkaline potassium permanganate | Alkaline potassium permanganate and acidified potassium dichromate are oxidising agents that turn ethanol into ethanoic acid; the permanganate loses its purple colour and the dichromate turns from orange to green. | 4.3 |
| allotrope | One of the different forms of the same element in the same physical state, with the atoms arranged differently, e.g. diamond and graphite are allotropes of carbon. | 4.1 |
| carbon monoxide | A poisonous gas CO formed when carbon compounds burn in too little oxygen. | 1.1 1.3 3.1 4.3 |
| carboxylic acid | A compound containing the group $-\mathrm{COOH}$, e.g. ethanoic acid; names end in -oic acid. | 4.2 4.3 4.4 |
| catalyst | A substance that speeds up a chemical reaction without being used up, e.g. nickel in hydrogenation. | 1.1 4.3 4.4 |
| catenation | The ability of atoms of an element to join one another into long chains, branched chains and rings; carbon shows it strongly because the C–C bond is strong. | 4.2 |
| combustion | The burning of a substance in oxygen with release of heat and light; a carbon compound burning completely gives carbon dioxide and water. | 1.1 1.3 4.1 4.3 |
| covalent bond | A bond formed by the sharing of a pair of electrons between two atoms, each shared pair counting towards the outer shell of both atoms, e.g. in $\mathrm{H_{2}}$, $\mathrm{CH_{4}}$ and $\mathrm{CO_{2}}$. | 4.1 |
| covalent compound | A compound made of molecules whose atoms are joined by covalent bonds; usually has low melting and boiling points and does not conduct electricity. | 4.1 |
| dehydration | The removal of water from a compound; ethanol heated with excess concentrated sulphuric acid at 443 K is dehydrated to ethene. | 4.4 |
| denatured alcohol | Ethanol made unfit for drinking by adding poisonous methanol and a bad-tasting coloured substance, so that industrial alcohol is not misused. | 4.4 |
| detergent | A cleaning agent made of sodium salts of sulphonic acids (or ammonium salts) with long hydrocarbon chains; it forms micelles but its calcium and magnesium salts are soluble, so it works in hard water. | 2.3 4.4 |
| double bond | Two shared pairs of electrons between two atoms, drawn as two lines, as in O=O or C=C. | 4.1 4.2 4.3 |
| electron-dot structure | A diagram of a molecule showing the outer electrons of its atoms as dots and crosses, with shared pairs between the atoms and lone pairs on them. | 4.1 |
| ester | A sweet-smelling compound formed from a carboxylic acid and an alcohol, e.g. ethyl ethanoate $\mathrm{CH_{3}COOC_{2}H_{5}}$; used in perfumes and flavourings. | 4.4 |
| esterification | The reaction of a carboxylic acid with an alcohol, in the presence of a few drops of concentrated sulphuric acid, to give an ester and water. | 4.4 |
| fullerene | An allotrope of carbon made of hollow cage-like molecules; the first, $\mathrm{C_{60}}$, has 60 carbon atoms in a football shape. | 4.1 |
| functional group | An atom or group of atoms, such as $-\mathrm{OH}$, $-\mathrm{CHO}$ or $-\mathrm{COOH}$, that determines the chemical properties of a carbon compound. | 4.2 4.3 |
| glacial ethanoic acid | Pure ethanoic acid; it freezes to ice-like crystals below 290 K (17 °C). | 2.2 4.4 |
| hard water | Water containing dissolved calcium and magnesium salts, with which soap forms an insoluble scum. | 2.3 4.4 |
| homologous series | A family of carbon compounds with the same functional group and general formula, whose successive members differ by $-\mathrm{CH_{2}}-$ ($14\ \mathrm{u}$). | 4.2 |
| hydrocarbon | A compound containing only carbon and hydrogen, such as methane $\mathrm{CH_{4}}$ or ethene $\mathrm{C_{2}H_{4}}$. | 4.2 4.3 4.4 |
| hydrogenation | The addition of hydrogen to an unsaturated compound in the presence of a nickel or palladium catalyst; used to turn vegetable oils into solid vanaspati ghee. | 2.3 4.3 |
| hydrophilic and hydrophobic | Hydrophilic (water-loving) describes the ionic head of a soap molecule, which dissolves in water; hydrophobic (water-hating) describes its hydrocarbon tail, which dissolves in oil. | 4.4 |
| incomplete combustion | Burning in a limited supply of oxygen, which gives carbon monoxide and soot as well as carbon dioxide and water; the flame is yellow and sooty. | 4.3 |
| IUPAC name | The systematic name of a compound given by the rules of the International Union of Pure and Applied Chemistry: root for the number of carbons plus suffix or prefix for the functional group. | 1.1 4.2 |
| ketone | A compound containing the group $>\mathrm{C{=}O}$ inside a carbon chain, e.g. propanone; names end in -one. | 4.2 |
| lone pair | A pair of outer electrons that belongs to one atom and is not shared in a bond, e.g. the two lone pairs on oxygen in water. | 4.1 |
| micelle | A spherical cluster of soap or detergent molecules in water, with the oil-loving tails inwards around a droplet of oil and the water-loving heads outwards. | 4.4 |
| molecule | The smallest independent unit of a covalent substance, a group of atoms joined by covalent bonds, e.g. $\mathrm{H_{2}O}$, $\mathrm{CH_{4}}$. | 1.1 1.2 2.1 2.2 |
| saponification | The reaction of an ester with sodium hydroxide to give an alcohol and the sodium salt of the acid; applied to fats and oils it gives soap and glycerol. | 4.4 |
| saturated compound | A hydrocarbon in which the carbon atoms are joined only by single bonds; the alkanes, general formula $\mathrm{C_{n}H_{2n+2}}$. | 4.2 4.3 |
| scum | The insoluble calcium or magnesium salt of the soap acid formed when soap is used in hard water, e.g. calcium stearate. | 4.4 |
| single bond | One shared pair of electrons between two atoms, drawn as one line, as in H–H or C–H. | 4.1 4.2 4.3 |
| soap | The sodium or potassium salt of a long-chain carboxylic acid, e.g. sodium stearate $\mathrm{C_{17}H_{35}COONa}$, with an ionic head and a hydrocarbon tail. | 2.1 2.2 2.3 4.4 |
| soot | Fine black particles of unburnt carbon formed in incomplete combustion; it blackens vessels held in a yellow flame. | 1.1 4.3 4.4 |
| structural formula | A drawing of a molecule showing its atoms with a line for each shared pair, e.g. H–O–H for water. | 4.1 4.2 |
| structural isomers | Compounds with the same molecular formula but different arrangements of atoms, e.g. butane and 2-methylpropane, both $\mathrm{C_{4}H_{10}}$. | 4.2 |
| substitution reaction | A reaction in which an atom or group of a compound is replaced by another, e.g. methane and chlorine in sunlight give chloromethane and hydrogen chloride. | 4.3 |
| triple bond | Three shared pairs of electrons between two atoms, drawn as three lines, as in N≡N or C≡C. | 4.1 4.2 4.3 |
| unsaturated compound | A hydrocarbon with at least one double bond (alkenes, $\mathrm{C_{n}H_{2n}}$) or triple bond (alkynes, $\mathrm{C_{n}H_{2n-2}}$) between carbon atoms. | 4.2 4.3 |
| vanaspati ghee | Solid saturated fat made by hydrogenating liquid vegetable oils with a nickel catalyst. | 4.3 |
| vinegar | A 5–8 % solution of ethanoic acid in water, used for pickles and as a preservative. | 1.1 1.3 2.1 2.2 |