The H+ concentration is related to the pH of the solution through the formula pH = -log(H+) while the OH- concentration is related to the pH of the solution through the formula pOH = -log(OH-). The product of H+ and OH- concentration is equal to Kw, 1 x 10 -14. hence OH- concentration is equal to 1 x 10 -14 / 3.5 × 10−6 equal to 2.86 x10^-9 M
