0.0115 M barium hydroxide gives twice the concentration of hydroxide ion 0.0330 moles/L = [OH-] [H3O+] = 10-14 /0.033 = 3.03*10-13 pOH = 1.48 pH = 12.52 (12.5 with 3 sig figs) Solution 0.0115 M barium hydroxide gives twice the concentration of hydroxide ion 0.0330 moles/L = [OH-] [H3O+] = 10-14 /0.033 = 3.03*10-13 pOH = 1.48 pH = 12.52 (12.5 with 3 sig figs).