What is the hydroxide ion concentration in an aqueous solution where the pH = 5?

Question

Quizplus · Accepted Answer

The pH of 5 indicates that the hydronium ion concentration is 1 × 10^-5 M. In a neutral solution, the concentration of hydroxide ions would also be 1 × 10^-5 M, but in this case, we know that the solution is acidic, so the hydroxide ion concentration must be lower than 1 × 10^-5 M. Using the Kw expression, we can see that [H3O+][OH-] = 1 × 10^-14, so [OH-] = 1 × 10^-14 / [H3O+] = 1 × 10^-14 / 1 × 10^-5 = 1 × 10^-9 M. Therefore, the hydroxide ion concentration is 1 × 10^-9 M.

What Is the Hydroxide Ion Concentration in an Aqueous Solution