Energy and Chemical Changes

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2. The movement of energy from one store to another, often seen in reactions.
3. A diagram that shows the energy changes during a chemical reaction.
8. A system that generates electricity using hydrogen and oxygen with only water as a by-product.
9. The gradual destruction of metals by reacting with substances in the environment.
11. The process of using electricity to break down a substance into its elements.
15. The process that releases energy when new chemical bonds are formed.
17. Devices that produce electricity through chemical reactions.
19. A substance with a pH lower than 7 that releases hydrogen ions in solution.
20. The idea that particles must collide with enough energy to react.
22. A substance that changes colour depending on whether it is in an acid or alkali.
23. The gain of electrons or the removal of oxygen from a substance.
25. A reaction that releases heat into the surroundings.
28. A burning reaction that releases energy, usually involving oxygen.
30. A method to find out how much acid or alkali is needed for neutralisation.
32. A solution that has a small amount of solute compared to the solvent.
33. A starting substance in a chemical reaction.
35. A reaction where a more reactive metal takes the place of a less reactive one in a compound.
36. Naturally occurring rocks that contain enough metal to be extracted profitably.
37. An acid that fully ionises in solution, like hydrochloric acid.

1. A numbered scale from 0 to 14 that shows how acidic or alkaline a solution is.
4. A reaction that absorbs heat from the surroundings.
5. The loss of electrons or the addition of oxygen to a substance.
6. A reaction between an acid and a base that produces a salt and water.
7. A reaction where reduction and oxidation happen at the same time.
10. The minimum energy needed for particles to react when they collide.
12. The amount of a substance in a given volume of solution.
13. The process that absorbs energy when chemical bonds are split apart.
14. A substance with a pH higher than 7 that releases hydroxide ions in solution.
16. An acid that only partially ionises in solution, like ethanoic acid.
18. A compound made when the hydrogen in an acid is replaced by a metal.
21. The specific type of corrosion that happens to iron when exposed to water and oxygen.
23. A list of metals arranged by how easily they react.
24. The negative electrode where positive ions gain electrons.
26. The liquid or solution that conducts electricity in electrolysis.
27. A charged particle formed when an atom gains or loses electrons.
28. A substance that speeds up a reaction without being used up.
29. The positive electrode where negative ions lose electrons.
31. The substances made when a chemical reaction takes place.
34. The process of obtaining metals from their ores.