We have been given the pOH value, then we can calculate the pH value. pH + pOH = 14 pOH = 9.85 pH = 14 - 9.85 = 4.15 We can calculate the hydronium ion concentration using pH value pH = -log [H₃O⁺] [H₃O⁺] = antilog(-pH) we can calculate antilog of pH by writing it as 10^(-4.15) [H₃O⁺] = antilog (-4.15) [H₃O⁺] = 7.07 x 10⁻⁵ M
