A weak base with Kb=4.240*10^-7 is added to water to make a 2.00*10^-1 M solution. what is the pH?
Since Kb is small, can assume that the dissociation is small relative to initial concentration of weak base.© BrainMass Inc. brainmass.com September 23, 2018, 1:55 pm ad1c9bdddf - https://brainmass.com/chemistry/acids-and-bases/ph-basic-solution-28775
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The solution is attached below in two files. the files are identical in content, only differ in format. The first is in MS Word XP Format, while the other is in Adobe pdf format. Therefore you can choose the format that is most suitable to you.
I used this, since formulas were used, and teh equation editor is much nicer than ascii ...
The solution shows how to find the required pH of the base.