An Arrhenius acid is a
substance that dissociates in water to form hydrogen ions or
protons (H⁺). For example hydrochloric acid: HCl(aq) → H⁺(aq) + Cl⁻(aq). An Arrhenius base is a substance that dissociates in water to form hydroxide ions (OH⁻). For example sodium hydroxide: NaOH(aq) → Na⁺(aq) + OH⁻(aq).
