In 1922 Donald D. van Slyke ( J. Biol. Chem., 52, 525)

Chapter 17, Problem 91

(choose chapter or problem)

In 1922 Donald D. van Slyke ( J. Biol. Chem., 52, 525) defined a quantity known as the buffer index: where represents the increment of moles of strong base to one liter of the buffer. For the addition of a strong acid, he wrote b = -dCa>d(pH). By applying this idea to a monoprotic acid and its conjugate base, we can derive the following expression: where C is the total concentration of monoprotic acid and conjugate base. (a) Use the above expression to calculate the buffer index for the acetic acid buffer with a total acetic acid and acetate ion concentration of and a pH = 5.0. 2.0 * 10-2 b = 2.303+ Kw 3H3O+4 + 3H3O+4 + CKa3H3O+4 1Ka + 3H3O+422 * (b) Use the buffer index from part (a) and calculate the pH of the buffer after the addition of of a strong acid. (Hint: Let ) (c) Make a plot of versus pH for a 0.1 M acetic acid buffer system. Locate the maximum buffer index as well as the minimum buffer indices.