Acids

Acids are substances that taste sour and change the colour of an indicator. Food acids, in lemons, vinegar and yoghurt, are weak and safe to eat. Industrial acids, such as hydrochloric acid used for cleaning, are strong: they burn skin, harm leaves and eat away limestone, marble and eggshell, fizzing as they do. An indicator such as red-cabbage water or pH paper shows an acid without tasting it.

Depth 1 · Foundation

You know that sour foods contain weak acids, that strong acids are dangerous and are never touched, smelled or tasted, how an indicator finds an acid, and that acids fizz with limestone, marble and eggshell and eat them away.

Depths of understanding

1
Foundation
You know that sour foods contain weak acids, that strong acids are dangerous and are never touched, smelled or tasted, how an indicator finds an acid, and that acids fizz with limestone, marble and eggshell and eat them away.
Opens after
Physical and chemical changeAn acid eating away stone is a chemical change: a new gas is made.

Your path here

What's still between you and Acids, depth 1, in the order you can learn it.

Where it fits

Builds on

Physical and chemical changeChemical Reactions

This concept

AcidsSolutions, Acids and Bases

Builds onThis conceptPhysical and chemical changeChemical Reactions AcidsSolutions, Acids and Bases

Makes these deeper

Once you know Acids, come back to these — they'll mean more.

Water pollutionDepth 2Factory waste often carries acids, so first see what acids do.