How do you calculate the pH of a buffer solution?

1 Answer
Sep 14, 2015

By use of the buffer equation:

#pH = pK_a + log_10([[A^-]]/[[HA]]).#


I am not going to derive this equation here (it is rather simple to do and worth doing), but it tells us that the #pH# of a given buffer should remain tolerably close to the #pK_a# of the acid that comprises the buffer. Added base or acid simply protonates/deprotonates the given base/acid, and should not grossly change solution #pH#.