Question

Calculate the ph of a solution that has a [oh-] = 2.50 x 10-4m.

Answer 1

It is so simple when you have [OH-] so you will use it to get POH from this formula:

POH = -㏒[OH]

         = -㏒ 2.5 x 10^-4

         = 3.6

when PH + POH = 14 

∴ PH = 14 - POH

         = 14 - 3.6 = 10.4