The Arrhenius definition of acids and bases was one of the earliest scientific explanations of acid–base behavior:
- Arrhenius Acid → A substance that increases the concentration of hydrogen ions (H⁺) or protons in an aqueous solution.
Example: HCl → H⁺ + Cl⁻ - Arrhenius Base → A substance that increases the concentration of hydroxide ions (OH⁻) in an aqueous solution.
Example: NaOH → Na⁺ + OH⁻
Key Points:
- Acids produce H⁺ (protons) in water.
- Bases produce OH⁻ (hydroxide ions) in water.
- The definition applies mainly to aqueous solutions (water-based).
- Neutralization occurs when H⁺ from the acid reacts with OH⁻ from the base to form water (H₂O).
Example: HCl + NaOH → NaCl + H₂O