Question

What is the hydroxide-ion concentration of a solution with a hydronium ion concentration of 1.0 x 10^-5 mole per liter?

Answer 1

The pH of an aqueous solution is equal to - log [H3O+]

pH = - log [1x10^-5] = 5

In an aqueous solution, the concentration of the hydroxide ion multiplied by the concentration of the hydronium ion is equal to 1x10^-14.

In equation form;

[OH-]*[H3O+] = 1x10^-14

Rearrange to solve for [OH-] to get

[OH-] = 1x10^-14 / [H3O+]
[OH-] = 1x10^-14 / [1x10^-5]

[OH-] = 1x10^-9 mol / L

Answer 2

@seiga is this the answer 1x10^-9 mol / L

Answer 3

yup/