Kw

Kw is the symbol for the ion product of water, representing the equilibrium constant for the self-ionization of water. It measures how much water naturally breaks down into hydrogen ions (H⁺) and hydroxide ions (OH⁻). At room temperature (around 25°C), Kw is always approximately 1.0 × 10⁻¹⁴, indicating that water molecules rarely split apart into ions. This value helps chemists understand the acidity or basicity of solutions: higher Kw means more ionization and a more reactive environment, while lower Kw means less ionization and a more stable, neutral solution.