The literature value for the equilibrium constant (K) for the auto-ionization of water (H₂O), often referred to as Kw, is:

Kw = 1.01 x 10⁻¹⁴ at 25 °C

This value represents the product of the concentrations of hydronium ions (H₃O⁺) and hydroxide ions (OH⁻) in pure water at 25 °C:

Kw = [H₃O⁺][OH⁻] = 1.01 x 10⁻¹⁴

Important Note: This value is specifically for the equilibrium constant (K), not the acid dissociation constant (Ka).

Key Points:

* Kw is temperature-dependent. It increases with increasing temperature.

* Kw is a measure of the extent of auto-ionization of water.

* The value of Kw is important for understanding the pH of solutions and for calculating the concentrations of H₃O⁺ and OH⁻ ions.

Remember that the value of Kw is generally rounded to 1.0 x 10⁻¹⁴ for simplicity in calculations.