What is the definition of an acid and a base? What is the Arrhenius definition of an acid and a base? What are acids?The Swedish chemist, Arrhenius proposed the following definition of an acid. An acid is a substance which ionises or dissociates in water to produce hydrogen ions, H+. For example, hydrochloric acid, HCl(aq) is a solution of hydrogen chloride in … [Read more...] about What is the definition of an acid and a base?