What is the hydroxide ion concentration in a solution of 0.40 M hypochlorous acid (HOCl) ?
K _a = 3.0×10^{- 8}

Question

What is the hydroxide ion concentration in a solution of 0.40 M hypochlorous acid (HOCl)? K _a = 3.0×10^{- 8}

Quizplus · Accepted Answer

The correct answer is C.The hydroxide ion concentration can be calculated using the following equation:$$K_a = \frac{[H^+][OH^-]}{[HOCl]}$$where K_a is the acid dissociation constant, [H^+] is the hydrogen ion concentration, [OH^-] is the hydroxide ion concentration, and [HOCl] is the hypochlorous acid concentration.Substituting the given values into the equation, we get:$$3.0 	imes 10^{-8} = \frac{[H^+][OH^-]}{0.40}$$$$[H^+][OH^-] = 1.2 	imes 10^{-8}$$Since the solution is neutral, [H^+] = [OH^-], so:$$[OH^-] = \sqrt{1.2 	imes 10^{-8}} = 9.1 	imes 10^{-11}$$

What Is the Hydroxide Ion Concentration in a Solution of 0.40