what is pka
But again, they're all considered to be weak acids, relative to the stronger ones. Let's talk about pKas. The pKa is defined as the negative log of the Ka. If we wanted to find the pKa for methanol, all we have to do is take the Ka and take the negative log of it. So the pKa is equal to the negative log of 2.9 times 10 to the negative 16. Let's get out the calculator and let's do that. Negative log of 2.9 times 10 to the negative 16.