Calculating pH of a known molarity of a basic solution

The hydroxide ion concentration can be found from the pOH by the reverse mathematical operation employed to find the pOH.

[OH-] = 10-pOH or [OH-] = antilog ( - pOH)

Example: What is the hydroxide ion concentration in a solution that has a pOH of 5.70?

5.70 = - log [OH-]

-5.70 = log[OH-]

[OH-] = 10-5.70 = 2.00 x 10-6 M

calculate 10-5.70, or "inverse" log (- 5.70).