A sodium hydroxide solution has a pH of 11.40, what is the [H₃O⁺] in this solution? A) 4.0 × 10^-26 M B) 4.0 × 10^-12 M C) 2.5 × 10^-3 M D) 2.5 × 10¹¹ M

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Quizplus · Accepted Answer

Sodium hydroxide is a strong base which means it completely dissociates in water. The OH- ions in the solution will react with water to form H2O and OH-. This means that the concentration of OH- in the solution will be equal to the concentration of the sodium hydroxide added. pOH = 14 - pH = 14 - 11.40 = 2.60 [OH-] = 10^-pOH = 10^-2.60 = 2.51 × 10^-3 M Since sodium hydroxide is a strong base, it will react with water to form Na+ and OH-. The concentration of Na+ will be the same as the concentration of the sodium hydroxide added. [H+] [OH-] = 1.0 × 10^-14 M^2 [H₃O⁺] = [H2O] = 1.0 × 10^-14 / [OH-] = 1.0 × 10^-14 / 2.51 × 10^-3 = 3.98 × 10^-12 M Therefore, the answer is B: 4.0 × 10^-12 M.

A Sodium Hydroxide Solution Has a PH of 11