Arrhenius Acids and Bases: Acids increase H⁺ concentration; bases increase OH⁻ concentration in aqueous solution.
Diagram explaining Arrhenius acids and bases, showing that acids increase H⁺ ions and bases increase OH⁻ ions in aqueous solution with chemical equations HA(aq) → H⁺(aq) + A⁻(aq) and BOH(aq) → B⁺(aq) + OH⁻(aq).