Avery common buffer agent used in the study of biochemical processes is the weak base TRIS, (HOCH₂)₃ CNH₂, which has a pK_b of 5.91 at 25 °C. A student is given a sample of the hydrochloride of TRIS together with standard solutions of 10 M NaOH and HCl.

(a) Using TRIS, how might the student prepare 1 L of a buffer of pH = 7.79?

(b) In one experiment, 30 mmol of protons are released into 500 mL of the buffer prepared in part (a). Is the capacity of the buffer sufficient? What is the resulting pH?

(c) Another student accidentally adds 20 mL of 10 M HCl to 500 mL of the buffer solution prepared in part (a). Is the buffer ruined? If so, how could the buffer be regenerated?