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800 Chapter 14 | Acid-Base Equilibria
70. Propionic acid, C2H5CO2H (Ka = 1.34 10−5), is used in the manufacture of calcium propionate, a food preservative. What is the hydronium ion concentration in a 0.698-M solution of C2H5CO2H?
71. White vinegar is a 5.0% by mass solution of acetic acid in water. If the density of white vinegar is 1.007 g/cm3, what is the pH?
72. The ionization constant of lactic acid, CH3CH(OH)CO2H, an acid found in the blood after strenuous exercise, is 1.36 10−4. If 20.0 g of lactic acid is used to make a solution with a volume of 1.00 L, what is the concentration of hydronium ion in the solution?
73. Nicotine, C10H14N2, is a base that will accept two protons (K1 = 7 10−7, K2 = 1.4 10−11). What is the concentration of each species present in a 0.050-M solution of nicotine?
74. The pH of a 0.20-M solution of HF is 1.92. Determine Ka for HF from these data.
75. The pH of a 0.15-M solution of is 1.43. Determine Ka for from these data.
76. The pH of a 0.10-M solution of caffeine is 11.16. Determine Kb for caffeine from these data:
77. The pH of a solution of household ammonia, a 0.950 M solution of NH3, is 11.612. Determine Kb for NH3 from these data.
14.4 Hydrolysis of Salt Solutions
78. Determine whether aqueous solutions of the following salts are acidic, basic, or neutral: (a) Al(NO3)3
(b) RbI
(c) KHCO2
(d) CH3NH3Br
79. Determine whether aqueous solutions of the following salts are acidic, basic, or neutral: (a) FeCl3
(b) K2CO3
(c) NH4Br
(d) KClO4
80. Novocaine, C13H21O2N2Cl, is the salt of the base procaine and hydrochloric acid. The ionization constant for procaine is 7 10−6. Is a solution of novocaine acidic or basic? What are [H3O+], [OH−], and pH of a 2.0% solution by mass of novocaine, assuming that the density of the solution is 1.0 g/mL.
14.5 Polyprotic Acids
81. Which of the following concentrations would be practically equal in a calculation of the equilibrium concentrations in a 0.134-M solution of H2CO3, a diprotic acid: [OH−], [H2CO3],
No calculations are needed to answer this question.
82. Calculate the concentration of each species present in a 0.050-M solution of H2S.
83. Calculate the concentration of each species present in a 0.010-M solution of phthalic acid, C6H4(CO2H)2.
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