Given the following equilibrium: H2O + H2O <-> H3O+ + OH- and the Kw = 10^-14, determine the concentration of OH- species after the addition of 1 mmol of HCl to 1 L of neutral water.

As HCl is a strong acid, it will fully dissociate in water, releasing 1 mmol of H⁺, which will be the final concentration of protons in solution. The autoprotolysis equilibrium of water (or K_w) at 25 ºC is defined as [H⁺] x [OH^-] = 10^-14Therefore [OH^-] = 10^-14 / 1 = 10^-14 mmol