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Alkali - GCSE Chemistry Definition

Reviewed by: Philippa Platt

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An alkali is a type of base that dissolves in water to produce hydroxide ions (OH⁻), leading to a solution with a pH greater than 7. In GCSE Chemistry, alkalis are often encountered in the context of neutralisation reactions, where they react with acids to form water and a salt.

Common examples of alkalis include sodium hydroxide (NaOH) and potassium hydroxide (KOH). They are characterised by their slippery feel, ability to turn red litmus paper blue, and their corrosive nature, which means they must be handled with care in the laboratory. Understanding alkalis is fundamental for studying acid-base reactions and the pH scale.

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Philippa Platt

Reviewer: Philippa Platt

Expertise: Chemistry Content Creator

Philippa has worked as a GCSE and A level chemistry teacher and tutor for over thirteen years. She studied chemistry and sport science at Loughborough University graduating in 2007 having also completed her PGCE in science. Throughout her time as a teacher she was incharge of a boarding house for five years and coached many teams in a variety of sports. When not producing resources with the chemistry team, Philippa enjoys being active outside with her young family and is a very keen gardener

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