The pH of a 0.24 M solution of dimethylamine is 12.01. Calculate the kb for dimethylamine. Please show steps?

Ok here we go...

First you have the pH which is 12.01.

From this value you can calculate the pOH because we know that pH + pOH = 14.

Therefore, 14 - 12.01 = 1.99 (pOH)

Then we can calculate the hydroxide concentration.

You do this by taking the anti-log of the pOH or in simpler terms, [OH-] = 10^-1.99

When you do this you get approximately 1.023 x 10^-2 M as the OH- concentration.

From this you can calculate the Kb value. If you were to set up an I.C.E table for this reaction (even though you don't really need to) you would see that you take the inital concentration for dimethylamine that they give you which is 0.24 M and subtract the concentration we calculated for OH-.

What you get from this is approximately 0.23 M.

Then you can write out the Kb expression as:

Kb = (1.023 x 10^-2 M)^2 / (0.22977 M)

The final value for Kb is approximately 4.5 x 10^-4

Hope this helps and answers your question!!!!