Question

Explain calculation of pH of a solution from disassociation constant.

Answer 1

If the acid you are hoping to calculate pH is a weak acid, you can calculate it in the following way.

You can write down the simple equation with the dissociation constant.

When the acid is weak, as you already know, only a tiny portion will dissolve.

Therefore, you can substitute the [H+] as an unknown term.

Then you can quickly calculate the pH of the solution with the pH formula.