Bases are substances that can react with acids and neutralise them. Alkalis are bases that are soluble in water. The pH scale measures how acidic or alkaline a substance is. Substances with a pH lower than 7 are acidic, those with a pH of 7 are neutral and those with a pH greater than 7 are alkaline.

Bases and acids

Bases are substances that can react with acids and neutralise them. Bases such as metal oxides and metal hydroxides react with acids to form neutral products.

Examples of bases include:

• copper(II) oxide
• zinc hydroxide.

An…