When does equilibrium typically lie in the ionization of water?

The ionization of water can be represented by the equilibrium expression for the dissociation of water into hydrogen ions (H⁺) and hydroxide ions (OH⁻):

[ 2H_2O \rightleftharpoons H_3O^+ + OH^- ]

At any given temperature, this reaction reaches an equilibrium state characterized by a very low concentration of ions compared to the concentration of un-ionized water. The concentration of H⁺ ions and OH⁻ ions in pure water at equilibrium at room temperature is about (1 \times 10^{-7} M), which is significantly lower than the concentration of un-ionized water molecules. This indicates that the equilibrium position lies significantly towards the left side of the equation, favoring the reactants (un-ionized water) over the products (hydronium and hydroxide ions).

Therefore, the correct answer is that the equilibrium lies far to the left. This reflects the stability of the water molecule in its neutral state rather than in its ionized form, highlighting the primarily un-ionized nature of water at equilibrium.