Salt C3 key words Word equation Hydrogen chloride gas Tectonic plates Hydrogen sulphide gas Magnetism Chlorine Sedimentary rocks Bleach Grains LeBlanc process Fossils Alkali Acts Erosion Microorganisms Evaporation Chlorination Preservative Organic matter Dissolve Solution Toxic Brine Accumulate Crystallise Synthetic Filter Persistent organic pollutants Centrifuge (POPs) Subsidence Extruded Flavouring Incinerator Theory Landfill

Alkali Plasticiser Neutralise Leach Phthalates Electrolysis Life cycle assessment Biodegradable

Accumulate To collect together and increase in quantity, e.g. bioaccumulation of chemicals in a food chain. Alkali A compound that dissolves in water to give a solution with a pH higher than 7. An alkali can be neutralised by an acid to form a salt. Solutions of alkalis contain hydroxide ions. Alkali Acts The Acts of Parliament passed in the UK to control levels of pollution. They led to the formation of the Alkali inspectorate that checked at least 95% of acid fumes were removed from the chimneys in chemical factories. Biodegradable Materials that are broken down in the environment by microorganisms. Most synthetic products are not biodegradable. Bleach A chemical that can destroy unwanted colours. A common bleach is a solution of chlorine in sodium hydroxide. Brine A solution of sodium chloride (salt) in water. Centrifuge A piece of equipment used to separate a mixture of solids and liquids by spinning the mixture very fast. Chlorination The process of adding chlorine to water to kill microorganisms, so it is safe to drink. Chlorine A greenish toxic gas, used to bleach paper and textiles, and to treat water. Crystallise To form crystals, for example by evaporating the water from a solution of salt. Dissolve Some chemicals dissolve in liquids (solvents). E.g. salt dissolves in water. Electrolysis Splitting up a chemical into its elements by passing an electric current through it. Erosion The movement of soil mud and rock, caused by wind, water, ice, gravity and living organisms. Evaporation The change of state from a liquid to a gas. Extruded A plastic is shaped by being forced through a mould. Filter To separate a solid from a liquid by passing it through filter paper. Flavouring Mixtures of chemicals that give foods, sweets, toothpaste and other products their flavours. Fossils The stony remains of animals/plants that lived millions of years ago, or an imprint it has made in a surface (e.g. footprint). Grains Small pieces of a substance, e.g. grains of sand. Hydrogen chloride gas An acid gas that is toxic and corrosive and is produced by the Leblanc process. Hydrogen sulphide gas A poisonous gas that smells of rotten eggs. Incinerator A factory for burning rubbish and generating electricity. Landfill Disposing of rubbish in holes in the ground. Leach The movement of plasticisers from polymers into water (or another liquid) that is flowing past the polymer. Leblanc process A process that used chalk (calcium carbonate), salt (sodium chloride) and coal to make the alkali, sodium carbonate. The Leblanc process was highly polluting. Life cycle assessment A way of analysing the production, use and disposal of a product to add up the total energy and water used and the effects on the environment. Magnetism A property of a material that means it is attracted to a magnet. Microorganisms A living organism that can only be seen through a microscope. They include bacteria, viruses and fungi. Neutralise When an acid reacts with an alkali to form a salt. During the reaction, hydroxide ions from the alkali combine with hydrogen ions from the acid to create water. Organic matter Material from dead plants and animals. Persistent organic pollutants (POPs) A POP is an organic compound that does not break down in the environment for a very long time. They can spread widely around the world and build up in the fatty tissue of animals and people. Phthalates Chemicals that are used as a plasticiser, added to polymers to make them more flexible. Plasticiser A chemical (usually a small molecule) added to polymers to make them more flexible. Preservative A chemical added to food to stop it going bad. Salt An ionic compound formed when an acid neutralises an alkali or a metal reacts with a non-metal. Sedimentary rocks Rock formed from layers of sediment. Solution Formed when a solid, liquid or gas dissolves in a solvent (a liquid such as water). Subsidence The sinking of the ground’s surface when it collapses into a hole beneath it. Synthetic A material made by a chemical process, not naturally occurring. Tectonic plates Giant slabs of rock (about 12, comprising crust and upper mantle) that make up the Earth’s outer layer. Theory A scientific explanation that is generally accepted by the scientific community. Toxic A chemical that may lead to serious health risks, or even death, if breathed in, swallowed or taken in through the skin. Word equation A summary in words of a chemical reaction.