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Problem 54
Write the chemical equation and the Ka expression for the acid dissociation of each of the following acids in aqueous solution. First show the reaction with H+(a)q as a product and then with the hydronium ion: (a) C6H5COOH (b) HCO3-
- Lactic acid CH3CH(OH)COOH has one acidic hydrogen. A 0.10 M solution of lactic acid has a pH of 2.44. Calculate Ka.
Problem 55
Problem 56
Phenylacetic acid 1C6H5CH2COOH2 is one of the substances that accumulates in the blood of people with phenylketonuria, an inherited disorder that can cause mental retardation or even death. A 0.085 M solution of C6H5CH2COOH has a pH of 2.68. Calculate the Ka value for this acid.
Problem 57
A 0.100 M solution of chloroacetic acid 1ClCH2COOH2 is 11.0% ionized. Using this information, calculate 3ClCH2COO-4, 3H+4, 3ClCH2COOH4, and Ka for chloroacetic acid.
Problem 58
A 0.100 M solution of bromoacetic acid 1BrCH2COOH2 is 13.2% ionized. Calculate 3H+4, 3BrCH2COO-4, 3BrCH2COOH4 and Ka for bromoacetic acid.
- A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains (Ka = 1.8 * 10^-5), calculate the concentration of acetic acid in the vinegar.
Problem 59
Problem 60
If a solution of HF 1Ka = 6.8 * 10-42 has a pH of 3.65, calculate the concentration of hydrofluoric acid.
- The acid-dissociation constant for benzoic acid C6H5COOH is 6.3 * 10^-5. Calculate the equilibrium concentrations of H3O+, C6H5COO-, and C6H5COOH in the solution if the initial concentration of C6H5COOH is 0.050 M.
Problem 61
Problem 62
The acid-dissociation constant for chlorous acid 1HClO22 is 1.1 * 10-2. Calculate the concentrations of H3O+, ClO2-, and HClO2 at equilibrium if the initial concentration of HClO2 is 0.0125 M.
Problem 63a,b
Calculate the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (a) 0.095 M propionic acid (C2H5COOH) (b) 0.100 M hydrogen chromate ion (HCrO4-)
Problem 64c
Determine the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (c) 0.165 M hydroxylamine.
- Saccharin, a sugar substitute, is a weak acid with pKa = 2.32 at 25 °C. It ionizes in aqueous solution as follows: HNC7H4SO31(aq) ⇌ H+(aq) + NC7H4SO3-(aq). What is the pH of a 0.10 M solution of this substance?
Problem 65
- The active ingredient in aspirin is acetylsalicylic acid 1HC9H7O42, a monoprotic acid with Ka = 3.3 * 10^-4 at 25 °C. What is the pH of a solution obtained by dissolving two extra-strength aspirin tablets, each containing 500 mg of acetylsalicylic acid, in 250 mL of water?
Problem 66
- Calculate the percent ionization of hydrazoic acid (HN3) in solutions of each of the following concentrations (Ka is given in Appendix D): (a) 0.400 M, (b) 0.100 M, (c) 0.0400 M.
Problem 67
Problem 68
Calculate the percent ionization of propionic acid (C2H5COOH) in solutions of each of the following concentrations (Ka is given in Appendix D): (a) 0.250 M (b) 0.0800 M (c) 0.0200 M
Problem 69
Citric acid, which is present in citrus fruits, is a triprotic acid (Table 16.3). (a) Calculate the pH of a 0.040 M solution of citric acid. (b) Did you have to make any approximations or assumptions in completing your calculations? (c) Is the concentration of citrate ion 1C6H5O7 3-2 equal to, less than, or greater than the H+ ion concentration?
Problem 71a
Consider the base hydroxylamine, NH2OH. (a) What is the conjugate acid of hydroxylamine?
Problem 72a
The hypochlorite ion, ClO-, acts as a weak base. (a) Is ClO- a stronger or weaker base than hydroxylamine?
Problem 72c
The hypochlorite ion, ClO-, acts as a weak base. (b) When ClO- acts as a base, which atom, Cl or O, acts as the proton acceptor? (c) Can you use formal charges to rationalize your answer to part (b)?
- Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (a) dimethylamine, (CH3)2NH (b) carbonate ion, CO3^2- (c) formate ion, CHO2^-
Problem 73
Problem 74a
Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (a) propylamine, C3H7NH2
Problem 74c
Write the chemical equation and the Kb expression for the reaction of each of the following bases with water: (c) benzoate ion, C6H5CO2-
- Calculate the molar concentration of OH- in a 0.075 M solution of ethylamine (C2H5NH2); Kb = 6.4 * 10^-4. Calculate the pH of this solution.
Problem 75
- Calculate the molar concentration of OH- in a 0.724 M solution of hypobromite ion BrO-; Kb = 4.0 * 10^-6. What is the pH of this solution?
Problem 76
Problem 77a
Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic base: C10H15ON1aq2 + H2O1l2 Δ C10H15ONH+1aq2 + OH-1aq2 A 0.035 M solution of ephedrine has a pH of 11.33. (a) What are the equilibrium concentrations of C10H15ON, C10H15ONH+, and OH-?
Problem 77b
Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic base: C10H15ON1aq2 + H2O1l2 Δ C10H15ONH+1aq2 + OH-1aq2 A 0.035 M solution of ephedrine has a pH of 11.33. (b) Calculate Kb for ephedrine.
Problem 78
Codeine 1C18H21NO32 is a weak organic base. A 5.0 * 10-3M solution of codeine has a pH of 9.95. Calculate the value of Kb for this substance. What is the pKb for this base?
- Phenol, C6H5OH, has a Ka of 1.3 * 10^-10. (c) Is phenol a stronger or weaker acid than water?
Problem 79
Problem 80
Use the acid-dissociation constants in Table 16.3 to arrange these oxyanions from strongest base to weakest: SO42-, CO32-, SO32-, and PO43-.
Problem 81a
Given that Ka for acetic acid is 1.8 * 10-5 and that for hypochlorous acid is 3.0 * 10-8, which is the stronger acid?