pls help i need to do this in less than 2 hours :(( A buffer is made up of 250 mL each of 0.43 M KH2PO4 and 0.27 M K2HPO4.(Ka=6.2 x 10-8) Assuming that volumes are additive, calculate the pH of the buffer after addition of 100 mL of 0.8 M NaOH to the buffer solution