How does a buffer work?

1 Answer
Jun 3, 2016

Answer:

#pH = pK_a + log_10{[[A^_]]/[[HA]]}#

Explanation:

The buffer equation tells us that with appreciable concentrations of a weak acid, #HA#, and its conjugate base, #A^-#, the #pH# of the solution should remain tolerably close to the #pK_a# of the acid, whatever this is. Added (small) quantities of #H_3O^+# simply protonate #A^-#; likewise, small quantities of #HO^-# deprotonate #HA#. Free #HO^-# and #H_3O^+# are kept to a minimum, and the #pH# of the solution thus changes only marginally.

Biological processes (including our digestive system) are extensively and efficiently buffered.