<P> Because most acid--base solutions are typically very dilute, the activity of water is generally approximated as being equal to unity, which allows the ionic product of water to be expressed as: </P> <Dl> <Dd> K e q ≈ a H 3 O + ⋅ a O H − (\ displaystyle K_ (\ rm (eq)) \ approx a_ (\ rm (H_ (3) O ^ (+))) \ cdot a_ (\ rm (OH ^ (-)))) </Dd> </Dl> <Dd> K e q ≈ a H 3 O + ⋅ a O H − (\ displaystyle K_ (\ rm (eq)) \ approx a_ (\ rm (H_ (3) O ^ (+))) \ cdot a_ (\ rm (OH ^ (-)))) </Dd> <P> In dilute aqueous solutions, the activities of the solute particles are approximately equal to their concentrations . Thus, the ionization constant, dissociation constant, self - ionization constant, or ionic product of water, symbolized by K, may be given by: </P>

Why does pure water ionize under normal conditions