Topic 8 Acids and bases - 8.4 Strong and weak acids and bases

Nature of science: Improved instrumentation-the use of advanced analytical techniques has allowed the relative strength of different acids and bases to be quantified. (1.8) Looking for trends and discrepancies-patterns and anomalies in relative strengths of acids and bases can be explained at the molecular level. (3.1) The outcomes of experiments or models may be used as further evidence for a claim-data for a particular type of reaction supports the idea that weak acids exist in equilibrium. (1.9)


The pH depends on the concentration of the solution. The strength of acids or bases depends on the extent to which they dissociate in aqueous solution.

Strong and weak acids and bases differ in the extent of ionization.

Strong acids and bases of equal concentrations have higher conductivities than weak acids and bases

A strong acid is a good proton donor and has a weak conjugate base.

A strong base is a good proton acceptor and has a weak conjugate acid.

Applications and skills

Distinction between strong and weak acids and bases in terms of the rates of their reactions with metals, metal oxides, metal hydroxides, metal hydrogen carbonates and metal carbonates and their electrical conductivities for solutions of equal concentrations


The terms ionization and dissociation can be used interchangeably.

See section 21 in the data booklet for a list of weak acids and bases.