Chapter 14, Problem 83AE

Tris(hydroxymethyl)aminomethane, commonly called TRIS or Trizma, is often used as a buffer in biochemical studies. Its buffering range is pH 7 to 9, and K_b is 1.19 × 10⁻⁶ for the aqueous reaction

a. What is the optimal pH for TRIS buffers?

b. Calculate the ratio [TRIS]/[TRISH⁺] at pH = 7.00 and at pH = 9.00.

c. A buffer is prepared by diluting 50.0 g TRIS base and 65.0 g TRIS hydrochloride (written as TRISHCl) to a total volume of 2.0 L. What is the pH of this buffer?

What is the pH after 0.50 mL of 12 M HCl is added to a 200.0-mL portion of the buffer?