A naturally occurring amino acid such as alanine has a group that is a carboxylic acid and a group that is a protonated amine. The pK_a values of the two groups are shown.

d. Draw the structure of alanine in a solution at pH = 12.

For each of the following compounds, draw the form that predominates at pH = 3, pH = 6, pH = 10, and pH = 14:

a. CH₃COOH (pK_a = 4.8)

For each of the following compounds (here shown in their acidic forms), write the form that ­predominates in a solution with a pH = 5.5:

e. ⁺NH4 (pK_a = 9.4)

f. HC≡N (pK_a = 9.1)

Indicate whether an alcohol (ROH) with a pK_a value of 15 has more charged or more neutral molecules in a solution with the pH values given in Problem 41.

1. pH = 1

2. pH = 3

3. pH = 5

Indicate whether an alcohol (ROH) with a pK_a value of 15 has more charged or more neutral molecules in a solution with the pH values given in Problem 41.

3. pH = 7

4. pH = 10

5. pH = 13

For the following acid–base reaction, (c) calculate the ratio of butan-2-ol to 2-butoxide.

What percent of imidazole is protonated at physiological pH (7.4)?

For the following acid–base pairs, (iii) predict the favored side of equilibrium; (iv) calculate K_eq;

(h)

Which of the following is a correct statement about the equilibrium constant ($K$) in a chemical reaction?