If a chemist wishes to prepare a buffer that will be effective at a pH of 5.0 and 25C, which of the following would be the best choice for the acid component? and WHY?
a. An acid with a ka equal to 6.6 x 10^-6
b. An acid with a ka equal to 1.5 x 10^-11
c. An acid with a ka equal to 5.6 x 10^-8
d. An acid with a ka equal to 5.0 x 10^-10
e. An acid with a ka equal to 8.5 x 10^-5