GlossariesGCSE GlossariesGCSE Chemistry GlossaryMetal Hydroxide

Metal Hydroxide - GCSE Chemistry Definition

Reviewed by: Richard Boole

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A metal hydroxide is a compound made of a metal ion and hydroxide ions (OH-). Metal hydroxides can form when a metal reacts with water or when a metal oxide reacts with water. These compounds act as bases, and many of them are alkaline, meaning they can dissolve in water to form solutions with pH above 7.

For example:

  • Sodium hydroxide (NaOH)

  • Calcium hydroxide [Ca(OH)2]

Metal hydroxides can turn red litmus paper blue and take part in neutralisation reactions with acids to form a salt and water:

metal hydroxide + acid → salt + water

Understanding metal hydroxides is important in GCSE Chemistry for explaining acid–base reactions, alkalinity, and their use in neutralising acids.

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Richard Boole

Reviewer: Richard Boole

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