| A | B |
|---|
| acid | A corrosive substance with a pH below 7. |
| alkali | A corrosive substance with a pH above 7. |
| neutral | A substance which is not an acid or an alkali. |
| indicator | A liquid or paper which changes colour in an acid or alkali. |
| litmus | A simple indicator made from lichen. |
| universal indicator | An indicator with a range of colours showing the pH scale. |
| neutralisation | When an acid "cancels out" an alkali or an alkali "cancels out" an acid. |
| pH scale | Numbers 1 to 14 which show how acidic or alkaline a substance is. |
| corrosive | A substance which "eats away at solid" substances. |
