Acetic acid has a Ka of 1.8×10^−5. Three acetic acid/acetate buffer solutions, A, B, and C, were made using varying concentrations:

a. [acetic acid] ten times greater than [acetate],
b. [acetate] ten times greater than [acetic acid], and
c. [acetate]=[acetic acid].

Match each buffer to the expected pH.

pH = 3.74 ; pH = 4.74 ; pH = 5.74

How many grams of dry NH4Cl need to be added to 2.30 L of a 0.600 M solution of ammonia, NH3, to prepare a buffer solution that has a pH of 8.71? Kb for ammonia is 1.8×10^−5. Express your answer with the appropriate units.