Bruice - Organic Chemistry 8th Edition

Ch. 2 - Acids and Bases:Central to Understanding Organic Chemistry

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Bruice 8th Edition

Ch. 2 - Acids and Bases:Central to Understanding Organic Chemistry

Problem 1

Which of the following are not acids?

CH₃COOH, CO₂ , HNO₂ , HCOOH, CCl₄

Problem 2a,b

Consider the following reaction: HBr + ^-C≡N ⇌ Br⁻ + HC≡N

a. What is the acid on the left side of the equation?

b. What is the base on the left side of the equation?

Problem 2c,d

Consider the following reaction:

HBr + ^-C≡N ⇌ Br⁻+ HC≡N

c. What is the conjugate base of the acid on the left?

d. What is the conjugate acid of the base on the left?

Problem 2g,h

Consider the following reaction:

HBr + ^-C≡N ⇌ Br⁻+ HC≡N

g. What is the conjugate base of the acid on the right?

h. What is the conjugate acid of the base on the right?

Problem 4a

What is the conjugate acid of each of the following?

1. NH₃

2. Cl⁻

3. HO⁻

4. H₂O

Problem 4b

What is the conjugate base of each of the following?

1. NH₃

2. HBr

3. HNO₃

4. H₂O

Problem 5ab

a. Which is a stronger acid: one with a pK_a of 5.2 or one with a pK_a of 5.8?

b. Which is a stronger acid: one with an acid dissociation constant of 3.4 × 10⁻³ or one with an acid dissociation constant of 2.1 × 10⁻⁴?

Problem 6a

An acid has a K_a of 4.53 × 10⁻⁶ in water. What is its K_eq for reaction with water in a dilute solution? ([H₂O] = 55.5 M)

Problem 7a

Butyric acid, the compound responsible for the unpleasant odor and taste of sour milk, has a pK_a value of 4.82. What is its Ka value? Is it a stronger acid or a weaker acid than vitamin C?

Problem 8a

Antacids are compounds that neutralize stomach acid. Write the equations that show how Milk of Magnesia, Alka-Seltzer, and Tums remove excess acid.

a. Milk of Magnesia: Mg(OH)₂

b. Alka-Seltzer: KHCO₃ and NaHCO₃

c. Tums: CaCO₃

Problem 10a,b,c

Draw the conjugate acid of each of the following:

a. CH₃CH₂OH

b. CH₃CH₂O⁻

Problem 12c,d

Estimate the pKa values of the following compounds:

c. CH₃CH₂COOH

d. CH₃CH₂CH₂N⁺H₃

Problem 13

a. Which is a stronger base: CH₃COO⁻ or HCOO⁻? (The pK_a of CH₃COOH is 4.8; the pK_a of HCOOH is 3.8.)

b. Which is a stronger base: HO⁻ or ^-NH₂? (The pK_a of H2O is 15.7; the pK_a of NH3 is 36.)

c. Which is a stronger base: H₂O or CH₃OH? (The pK_a of H3O+ is −1.7; the pK_a of CH₃O⁺H₂ is −2.5.)

Problem 15

Does methanol behave as an acid or a base when it reacts with methylamine?

Problem 16a(1,2)

For each of the acid–base reactions in [Section 2.3], compare the pK_a values of the acids on either side of the equilibrium arrows to prove that the equilibrium lies in the direction indicated.

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Problem 16a(3,4)

For each of the acid–base reactions in [Section 2.3], compare the pK_avalues of the acids on either side of the equilibrium arrows to prove that the equilibrium lies in the direction indicated.

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Problem 17a

Ethyne (HC≡CH) has a pK_a value of 25, water has a pK_a value of 15.7, and ammonia (NH3) has a pKa value of 36. Draw the equation, showing equilibrium arrows that indicate whether reactants or products are favored, for the acid–base reaction of ethyne with

a. HO^-.

Problem 17b,c

Ethyne (HC≡CH) has a pK_a value of 25, water has a pK_a value of 15.7, and ammonia (NH₃) has a pK_a value of 36. Draw the equation, showing equilibrium arrows that indicate whether reactants or products are favored, for the acid–base reaction of ethyne with

b. ⁻NH₂.

c. Which would be a better base to use if you wanted to remove a proton from ethyne, HO⁻ or ^-NH₂?