7.2.1—Names and formulas of the common acids
- Syllabus
- 9701–2028–2029
- Objective
- 7.2.1
- Level
- AS
Acids donate protons and bases accept them in aqueous chemistry
An acid is a proton donor and a base is a proton acceptor in the Brønsted–Lowry model. In water, acids form H₃O⁺ while bases remove protons from water or another donor.
The model focuses on proton transfer, so the same species can act as an acid in one reaction and a base in another.
HCl + H₂O → H₃O⁺ + Cl⁻: HCl donates H⁺ and water accepts it. NH₃ accepts H⁺ from water, so NH₃ is a base.
A base is not defined only as a substance containing OH⁻. Ammonia is a Brønsted base even though its formula has no hydroxide ion.
ConceptA-Level CAIE Chemistry AS