Universal Indicator
Universal indicator changes colour in acids and alkalis.
Its colour shows the strength of an acid or alkali.
| strong acid |
= red |
| weak acid |
= orange / yellow |
| neutral |
= green |
| weak alkali |
= turquoise / blue |
| strong alkali |
= deep blue / purple |
The strength of an acid or alkali is shown on the pH
scale of numbers.
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