In the study of biochemical processes, a common buffering agent is the weak base trishydroxymethylaminomethane, (HOCH2)3CNH2, often abbreviated as Tris. At 25 °C, Tris has a pKb of 5.91. 
The hydrochloride of Tris is (HOCH2)3CNH3Cl, which can be abbreviated as TrisHCl. 
What volume of 10.0 M NaOH is needed to prepare a buffer with a pH of 7.79 using 31.52 g of TrisHCl? 
A: 6.7 mL 
The buffer from Part A is diluted to 1.00 L. To half of it (500. mL), you add 0.0200mol of hydrogen ions without changing the volume. What is the pH of the final solution? 
A: pH = 7.28 
What additional volume of 10.0 M HCl would be needed to exhaust the remaining capacity of the buffer after the reaction described in Part B?