As long as the pH is not less than ___________, at least 50% of a protonated amine with a pK_a value of 10.4 will be in its neutral, nonprotonated form.

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:

i. HON⁺H₃ (pK_a = 6.0)

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 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 a protonated amine (RN⁺H₃) with a pKa value of 9 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

4. pH = 7

5. pH = 10

6. pH = 13

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:

g. HNO₂ (pK_a = 3.4)

h. HNO₃ (pK_a = −1.3)