here is a buffer problem in my HW that I'm not sure how to do. Plz help me. Plz show me how. Thanks a lot. Formula: pH = pKa + log([B-]/[HB]) ***A buffer is made up of 0.500 L each of .300 M KH2PO4 and .400 M K2HPO4. Calculate a) The pH of the buffer after the addition of 0.0500 mole of HCl b) The pH of the buffer after the addition of 0.0500 mole of NaOH.