You have the following acids and their conjugate bases available:

Question

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.

Answer 1

i think the answer is A because it's pKa is the closest to pH 4.5.

Answer 2

B is wrong. A is right. Typically you want to pick pKa withing +/- 1 of the desired pH.

Answer 3

Christine! Are you doing AP Chem with k12?

Answer 4

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Answer 5

I love all of you man. This was my last question for AP chem! I will never have to take AP chem again HAHAH. THANK YOU ALL FOR THE AMAZING HELP!!!

Answer 6

Finally finished this course too