SPM Chemistry Form 5 Definition List

1. Effective collision (Collision theory) – collision that results in a chemical reaction where the particles collide with the correct orientation and are able to achieve the activation energy.
2. Homologous series – organic compounds (families) with similar formulae and properties.
3. Catalyst – a chemical that alter the rate of reaction.
4. Positive catalyst – increases the rate of reaction & lower the activation energy.
5. Negative catalyst – decreases the rate of reaction & higher the activation energy
6. Organic compounds – carbon-containing compound. Carbon atoms form covalent bonds.
7. Inorganic compounds – compounds from non-living things which do not contain the element carbon.
8. Saturated hydrocarbons – hydrocarbons containing only single bonds between all carbon atoms.
9. Unsaturated hydrocarbons – hydrocarbons containing at least one carbon-carbon double or triple bond.
10. Esterification – esters are produced
11. Vulcanisation – process which makes the natural rubber harder and increases its elasticity by adding sulphur.
12. Redox reaction – chemical reactions involving oxidation and reduction occurring simultaneously.
13. Flavouring – improve the taste or smell of food and restore taste loss due to food processing.
14. Stabilisers – help to mix two liquids that usually do not mix together so that they form an emulsion.
15. Thickeners – substances that thicken food and give the food a firm, smooth and uniform texture.
16. Precipitation – the heat change when one mole of a precipitate is formed from their ions in aqueous solution.
17. Displacement – the heat change when one mole of a metal is displaced from its salt solution by a more electropositive metal.
18. Neutralisation – the heat change when one mole of water is formed from the reaction between an acid and an alkali.
19. Combustion – the heat change when one mole of a substance is completely burnt in oxygen under standard conditions.