YEAR 9 Chemistry

4. – A reaction that absorbs energy from the surroundings.
5. Variable – The factor you measure.
8. – A reaction between an acid and a base to form salt and water.
10. – A measure of how hot or cold something is.
13. Rate – How fast a reaction happens.
15. – pH = 7; neither acidic nor basic.
17. – When reactions happen at equal rates in both directions (balanced).
20. – A scale from 0–14 showing how acidic or basic a solution is.
21. – Plant pigment (e.g. red cabbage juice) used as a natural pH indicator.
23. – A substance with pH < 7, produces hydrogen ions (H⁺).
25. Variables – Factors you keep the same to make the test fair.

1. – The ability of an indicator to show small changes in pH.
2. – A glass tube with a tap (stopcock) used to measure volumes of liquid accurately in titrations.
3. – A substance that changes colour in acids and bases (e.g. litmus, phenolphthalein, flavin/red cabbage).
6. – A base that dissolves in water.
7. Equation – A way of showing a chemical reaction using words (e.g. acid + metal → salt + hydrogen).
9. – When substances interact and change into new substances.
11. – How quickly/easily a substance reacts.
12. – A substance that reacts with acids, often produces hydroxide ions (OH⁻).
14. – The ability to do work or cause change.
16. – A reaction that releases energy, usually as heat or light.
18. – An element that is usually shiny, conducts heat/electricity, and reacts with acids.
19. Variable – The factor you change in an experiment.
22. – A small tap used to control liquid flow in a burette.
24. – A tool used to measure and transfer small, precise amounts of liquid.