Q1(c). Arrhenius acids and bases

Answer in brief

An Arrhenius acid increases aqueous H₃O⁺ concentration; an Arrhenius base increases aqueous OH⁻ concentration.

Key points

• An acid ionizes in water, for example HCl + H₂O → H₃O⁺ + Cl⁻.
• A base supplies hydroxide in water, for example NaOH → Na⁺ + OH⁻.
• Neutralisation is H₃O⁺ + OH⁻ → 2H₂O; the spectator ions form the salt. Acid/base strength depends on the extent of ionisation, not merely on concentration.
• The theory is mainly restricted to aqueous behaviour.