The concentration of the hydronium ion in an aqueous solution at 25 °C is 0.0092 M. What is the concentration of the hydroxide ion?

Answer 1

K_w is always equal to 1.0·10^-14

The formula is :

K_w=[H⁺][OH^-]

([H⁺] is the same thing as [H₃O⁺] is the hydronium ion)

So if [H⁺] is equal to 0.0092 M, just plug that in and solve for the [OH^-]

1·10^-14 = [0.0092][OH^-]

0.0092 0.0092

1.1·10^-12 = [OH^-]