Suppose that you were asked to create a buffer solution that has a pH at around 6. As a general rule, if you were asked to select an acid for the preparation of a buffer solution, you would choose an acid that has a pKa close to your desired pH (this will give your buffer nearly equivalent amounts of acid and conjugate base so it will be able to neutralize as much H+ and OH- as possible). Using the chart below, which acid would you choose to create your buffer?

Question

Suppose that you were asked to create a buffer solution that has a pH at around 6. As a general rule, if you were asked to select an acid for the preparation of a buffer solution, you would choose an acid that has a pKa close to your desired pH (this will give your buffer nearly equivalent amounts of acid and conjugate base so it will be able to neutralize as much H+ and OH- as possible). Using the chart below, which acid would you choose to create your buffer?

Name

Formula

Ka

pKa

Acetic Acid

HC2H3O2

1.8 x 10-5

4.7

Carbonic Acid

H2CO3

4.5 x 10-7

6.3

Citric Acid

H3C6H5O7

3.2 x 10-7

6.5

Sulfurous Acid

HSO3-

6.3 x 10-8

7.2

Group of answer choices

Citric Acid

Carbonic Acid

Acetic Acid

Sulfurous Acid

Answer 1

Based on the pKa values provided, the best choice for creating a buffer solution with a pH around 6 would be Carbonic Acid, as its pKa is the closest to the desired pH of 6.3.