The pH scale shows how acidic a substance is. Learn what pH means and how it is measured in this KS3 chemistry guide from BBC Bitesize.

Acids and alkalis react together in neutralisation reactions which produce salts and water. The salt name can be found from the name of the acid and alkali.

Acids react with some metals to produce salts and hydrogen. The salt name can be found from the name of the acid and metal.

Acids, bases and alkalis are found in the laboratory and at home. Acids and bases can neutralise each other. A base that can dissolve in water is also called an alkali.