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GCSE Chemistry · key term
The formation of ions when a substance dissolves in water.
Used by AQA and OCR
Specification 4.4.2.6, 4.7.2.4 · Paper 1, Paper 2
The formation of ions from neutral particles when a substance is dissolved or reacts.
Revise: Strong and Weak AcidsStrength describes the degree of ionisation of an acid. Concentration describes the amount of acid present in a given volume of solution. They are independent properties.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
The formation of ions from a substance when it dissolves in water.
Revise: Weak/Strong vs Dilute/ConcentratedWeak and strong describe the acid’s degree of ionisation in water. A strong acid ionises completely: its dissolved acid particles form ions. A weak acid ionises only partly: some particles form ions, while others remain as acid molecules.
Always keep strength and concentration separate: strength is the degree of ionisation, whereas concentration is the amount of acid in a given volume of solution.
Higher tier: compare the pH of weak and strong acids at the same concentration. Strength means degree of ionisation, not how dilute an acid is.
Explain ‘strong’ or ‘weak’ using the degree of ionisation, not the amount of acid dissolved.
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