Topic 8: Acids and bases - 8.1 Theories of acids and bases

Nature of science:

Falsification of theories - HCN altering the theory that oxygen was the element which gave a compound its acidic properties allowed for other acid-base theories to develop. 2.5

Theories being superseded-one early theory of acidity derived from the sensation of a sour taste, but this had been proven false. 1.9

Public understanding of science-outside of the arena of chemistry, decisions are sometimes referred to as "acid test" or "litmus test". 5.5


Essential idea: Many reactions involve the transfer of a proton from an acid to a base

A Brønsted-Lowry acid is a proton/H+ donor and a Brønsted-Lowry base is a proton/H+ acceptor

Amphiprotic species can act as both Brønsted-Lowry acids and bases.

A pair of species differing by a single proton is called a conjugate acid-base pair.

Applications and skills

Deduction of the Brønsted-Lowry acid and base in a chemical reaction.

Deduction of the conjugate acid or conjugate base in a chemical reaction.


Lewis theory is not required here.

The location of the proton transferred should be clearly indicated. For example,CH3COOH/CH3COO- rather than C2H4O2/C2H3O2-.

Students should know the representation of a proton in aqueous solution as both H+ (aq) and H3O+ (aq).

The difference between the terms amphoteric and amphiprotic should be covered.