You have the following acids and their conjugate bases available:
Acetic Acid: CH 3COOH/CH3COO-; Ka = 1.8 × 10-5
Carbonic Acid: H2CO3/HCO3-; Ka = 4.2 × 10-7
Hydrofluoric acid: HF/F-; Ka = 7.2 × 10-4
Which of these acid/conjugate base pairs would be the best choice for a buffer in the range of pH 4.5?
a. acetic acid
b. carbonic acid
c. hydrofluoric acid
I believe B. Please help.
i think the answer is A because it's pKa is the closest to pH 4.5.
posted by Christine
B is wrong. A is right. Typically you want to pick pKa withing +/- 1 of the desired pH.posted by DrBob222
Christine! Are you doing AP Chem with k12?posted by Jameson