Abuffer is made up of 0.300 l of each of 0.500 m kh2po4 and 0.317 m k2hpo4. assuming that volumes are additive, (a.) calculate the ph of the buffer after the addition of 0.0500 mol of hcl to 0.600 l of buffer and (b.) the ph of the buffer after the addition of 0.0500 lol of naoh to 0.600 l of the buffer. (pka=7.21)