Rank the following compounds from strongest to weakest acid:

CH₃CH₂OH; CH₃CH₂NH₂; CH₃CH₂SH; CH₃CH₂CH₃

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, draw the form that predominates at pH = 3, pH = 6, pH = 10, and pH = 14:

b. CH₃CH₂N⁺H₃ (pK_a = 11.0)

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

c. CF₃CH₂OH (pK_a = 12.4)

Give the products of the following acid–base reactions and indicate whether reactants or products are favored at equilibrium.

a.

Give the products of the following acid–base reactions and indicate whether reactants or products are favored at equilibrium.

b. CH₃CH₂OH + ^-NH₂ ⇌

Rank the following alcohols from strongest to weakest acid.

CH₂═CHCH₂OH; CH₃CH₂CH₂OH; HC≡CCH₂OH

Explain the relative acidities.

CH₂═CHCH₂OH, CH₃CH₂CH₂OH, HC≡CCH₂OH

A single bond between two carbons with different hybridizations has a small dipole. What is the direction of the dipole in the indicated bonds?

a.

b.

For each compound, indicate the atom that is most apt to be protonated.

a.

b.

c.

Given the K_a values, estimate the pK_a value of each of the following acids without using a calculator (that is, is it between 3 and 4, between 9 and 10, and so on?):

1. nitrous acid (HNO₂), K_a = 4.0 × 10⁻⁴

2. nitric acid (HNO₃), K_a = 22

3. bicarbonate (HCO₃⁻), K_a = 6.3 × 10⁻¹¹

4. hydrogen cyanide (HCN), K_a = 7.9 × 10⁻¹⁰

5. formic acid (HCOOH), K_a = 2.0 × 10⁻⁴

6. phosphoric acid (H₃PO₄), K_a = 2.1

b. Determine the exact pKa values, using a calculator.

c. Which is the strongest acid?

1. nitrous acid (HNO₂), K_a = 4.0 × 10⁻⁴

2. nitric acid (HNO₃), K_a = 22

3. bicarbonate (HCO₃⁻), K_a = 6.3 × 10⁻¹¹

4. hydrogen cyanide (HCN), K_a = 7.9 × 10⁻¹⁰

5. formic acid (HCOOH), K_a = 2.0 × 10⁻⁴

6. phosphoric acid (H₃PO₄), K_a = 2.1

Tenormin, a member of the group of drugs known as beta-blockers, is used to treat high blood pressure and improve survival after a heart attack. It works by slowing down the heart to reduce its workload. Which atom in Tenormin is the most basic?

From which of the following compounds can HO⁻ remove a proton in a reaction that favors product formation?

For each of the following pairs of reactions, indicate which one has the more favorable equilibrium constant (that is, which one most favors products):

1.

2.

Which of the four reactions has the most favorable equilibrium constant?

1.

You are planning to carry out a reaction that produces protons. The reaction will be buffered at pH = 10.5. Would it be better to use a protonated methylamine/methylamine buffer or a protonated ethylamine/ethylamine buffer? (pK_a of protonated methylamine = 10.7; pK_a of protonated ethylamine = 11.0)

a. Without using a calculator, estimate the pH of each of the following solutions:

1. [HO⁻] = 3.2 × 10⁻⁵

2. [H₃O⁺] = 8.3 × 10⁻¹

3. [H₃O⁺] = 1.7 × 10⁻³

b. Determine the exact pH, using a calculator.

Citrus fruits are rich in citric acid, a compound with three COOH groups. Explain the following:

a. The first pK_a (for the COOH group in the center of the molecule) is lower than the pK_a of acetic acid.

Citrus fruits are rich in citric acid, a compound with three COOH groups. Explain the following:

b. The third pK_a is greater than the pKa of acetic acid.

Given that pH + pOH = 14 and that the concentration of water in a solution of water is 55.5 M, show that the pK_a of water is 15.7. (Hint: pOH=−log [HO−])

How could you separate a mixture of the following compounds? The reagents available to you are water, ether, 1.0 M HCl, and 1.0 M NaOH.

If an acid with a pK_a of 5.3 is in an aqueous solution of pH 5.7, what percentage of the acid is present in its acidic form?

At what pH does 80% of the acid exist in its acidic form?