C7

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Bulk Chemicals

Back 1

Chemicals made by industry on a scale of thousands or millions of tonnes per year. e.g. sulfuric acid, nitric acid, sodium hydroxide, ethanol and ethanoic acid

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Fine Chemicals

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Chemicals made by industry in smaller quantities than bulk chemicals. e.g. used in food additives, medicines and pesticides.

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Feedstocks

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A chemical, or mixture of chemicals, fed into a process in the chemical industry

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Synthesis

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Making a new chemical by joining together simpler chemicals

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By-products

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Unwanted products of chemical synthesis. By-products are formed by side-reactions that happen at the same time as the main reaction, thus reducing the yield of the product required

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Sustainable

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Using the Earth's resources in a way that can continue in future, rather than destroying them

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Renewable resource

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Resources that can be replaced as quickly as they are used e.g. wood

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Percentage Yield

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A measure of the efficiency of a chemical synthesis

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Atom economy

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A measure of the efficiency of a chemical process. The atom economy for a process shows the mass of product atoms as a percentage of the mass of reactant atoms.

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Exothermic

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An exothermic reaction gives out energy to its surroundings

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Catalyst

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A chemical that speeds up a chemical reaction but is not used up in the process.

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Enzyme

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A biological catalyst

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Sustainable development

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A plan for meeting people's presents needs without spoiling the environment for the future

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Organic chemistry

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The study of carbon compounds. This includes all of the natural carbon compounds from living things and synthetic carbon compounds.

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Alkane

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Hydrocarbons found in crude oil. All the C-C bonds in alkanes are single bonds. e.g. Ethane

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Hydrocarbon

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A compound of hydrogen and carbon only

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Saturated

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In the molecules of a saturated compound, all of the bonds are single bonds. e.g. the fatty acids in animal fats

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Unsaturated

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There are double bonds in the molecules of unsaturated compounds. there is no spare bonding. e.g. the fatty acids in vegetable oils.

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Ethene

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Hydrocarbon. forms ethanol

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Alcohols

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Organic compounds containing reactive group -OH. e.g. ethanol

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Functional group

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A reactive group of atoms in an organic molecule. The hydrocarbon chain making up the rest of the molecule is generally unreactive with common reagents such as acids and alkalis. e.g. -OH in alcohols and -COOH in carboxylic acids.

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Fermentation

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The conversion of carbohydrates to alcohols and carbon dioxide using yeast

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Distillation

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A method of separating a mixture of two or more substances with different boiling points

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Biomass

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Plant material and animal waste that can be used as fuel. A renewable energy source

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Vinegar

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A sour-tasting liquid used as a flavouring and to preserve foods. It is a dilute acetic (ethanoic) acid made by fermenting beer, wine or cider

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Carboxylic acid

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organic compounds containing the reactive group -COOH. e.g. ethanoic acid.

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strong acid

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fully ionised to produce hydrogen ions when it dissolves in water

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Weak acid

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only slightly ionised to produce hydrogen ions when they dissolve in water

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Esters

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An organic compound made from a carboxylic acid and an alcohol. e.g. Ethyl ethanoate

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heat under reflux

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Heating a reaction mixture in a flask fitted with a vertical condenser. Vapours escaping from the flask condense and flow back into the reaction mixture

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Drying agent

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A chemical used to remove water from moist liquids or gases. e.g. anhydrous chloride and anhydrous sodium sulfate.

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Tap funnel

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A funnel with a tap to allow the controlled release of a liquid

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Glycerol

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an alcohol with three -OH groups. Its chemical name is propan -1,2,3-triol.

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Fatty acids

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Another name for carboxylic acids

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Fats

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esters of glycerol with long-chain carboxylic acids.

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Vegetable oils

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esters of glycerol with fatty acids. Most of the fatty acids are unsaturated when compared with the fatty acids in animal fats.

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Exothermic

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gives out energy to its surroundings

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Endothermic

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takes in energy from its surroundings

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Energy-level diagram

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diagram to show the difference in energy between the reactants and the products of a reaction

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Bond strength

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A measure of how much energy is needed to break a covalent bond between two atoms. Its measured in joules

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Activation energy

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The minimum energy needed in a collision between molecules if they are to react. It is the height of the energy barrier between reactants and products in a chemical change

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irreversible change

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A chemical change that can only go in one direction

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Equilibrium

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A state of balance in a reversible process when neither the forward nor the backward reaction is complete. The reaction appears to have stopped. Reactants and products are present and their concentration is not changing

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Dynamic equilibrium

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Chemical equilibria are dynamic. At equilibrium the forward and back reactions are still continuing but at equal rates so that there is no overall change.

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Nitrogen fixation

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The conversion of nitrogen gas into compounds either industrially or by natural means

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Haber process

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The reaction between nitrogen and hydrogen gas used to make ammonia on an industrial scale

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Le Chatelier's principle

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The principle that the position of an equilibrium will respond to oppose a change in the reaction conditions

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Limiting factor

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The factor that prevents the rate of growth of living things

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Triple bond

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A covalent bond between the two atoms involving the sharing of three pairs of electrons e.g. nitrogen gas. It makes the molecule very stable and unreactive

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Nitrogen cycle

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The continuing cycle of nitrogen, which is one of the elements that is essential for life. It is able to cycle between the atmosphere, lithosphere, hydrosphere, and biosphere

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Nitrogenase

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the enzyme system that catalyses the reduction of nitrogen gas to ammonia

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Qualitative

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any method for identifying the chemicals in a sample. e.g. thin-layer chromatography

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Quantitative

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any method for determining the amount of a chemical in a sample e.g. an acid-base titration

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Sample

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a small portion collected from a larger bulk of material for laboratory analysis

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Replicate sample

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two or more samples taken from the same material. They should be as similar as possible and analysed by the same procedure to help judge the precision of the analysis

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Representative sample

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A sample of a material that is as nearly identical as possible in its chemical composition to that of the larger bulk of the material sampled

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Chromatography

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an analytical technique in which the components of a mixture are separated by the movement of a mobile phase through a stationary phase

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Mobile phase

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The solvent that carries chemicals from a sample through a chromatographic column or sheet

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Stationary phase

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The medium through which the mobile phase passes in chromatography

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Aqueous

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a solution in which water is solvent

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Non-aqueous

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a solution in which a liquid other than water is a solvent

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Reference materials

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Known chemicals used in analysis for comparison with unknown chemicals

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Chromatogram

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the resulting record showing the separate chemicals at the end of a chromatography experiment

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Solvent front

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The furthest position reached by the solvent during paper or thin-layer chromatography

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Locating agent

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A chemical used to show up colourless spots on a chromatogram

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Retardation factor

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A ratio used in paper or thin-layer chromatography. If the conditions are kept the same, each chemical in a mixture will move a fixed fraction of the distance moved by the solvent front

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Retention time

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In chromatography, the time it takes for a component in a mixture to pass through the stationary phase

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Titration

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An analytical technique used to find the exact volumes of solutions that react with each other

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pipette

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Used to measure small volumes of liquids or solutions accurately. Can be used to deliver the same fixed solution again and again during a series of titrations

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End point

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The point during a titration at which the reaction is just complete.

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Burette

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A graduate tube with taps or valves used to measure the volume of liquids or solutions during quantitative investigations such as tritrations

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Standard solution

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a solution whose concentration is accurately known. Used in titrations

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Measurement uncertainty

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Variations in analytical results owing to factors that the analyst cannot control. Measurement uncertainty arises from both systematic and random errors

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Accuracy

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how close a quantitative results is to the true or 'actual' value

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Precision

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A measurement of the spread of quantitative results. If the measurements are precise all the results are very close in value