Cambridge IGCSE Chemistry · Syllabus 0620 · Acids, Bases and Salts
Weak Acid
What is Weak Acid?
An acid that is only partially dissociated into ions in aqueous solution, so that most of the acid remains as un-ionised molecules at any moment. Ethanoic acid is the weak acid named by this syllabus, shown by CH3COOH(aq) in equilibrium with H+(aq) + CH3COO-(aq), and partial dissociation is written with an equilibrium arrow.
This definition is part of the Acids, Bases and Salts chapter in Cambridge IGCSE Chemistry.
Common mistakes with Weak Acid
- “A strong acid is a concentrated acid, or a corrosive one.” Repair Strong describes the extent of dissociation in aqueous solution: complete for a strong acid, partial for a weak one. Concentrated describes how much acid there is per unit volume. They are independent, so a dilute strong acid and a concentrated weak acid both exist.