What is the H3O + ion concentration of a solution that has an OH - ion concentration of 1.0 * 10^-3M?

A) 1.0 * 10^-3M

B) 1.0 * 10^-7M

C) 1.0 * 10^-11M

D) 1.0 * 10^-14M

Answer: C. 1.0 * 10^-11M

Explanation:

First Step: Determine the pOH of the solution by taking the - Log [-OH]

pOH = - Log (1.0 * 10^-3)

= 3

Second Step : Obtain the pH, using the following equation; pH + pOH = 14

pH + 3 = 14, making pH the subject of the formular we then have;

pH = 14 - 3 = 11.

Last Step: Take the anti-log of the pH to get the concentration of H3O+.

∴ Anti-log of 11 = 1.0 * 10^-11M