CHEM 1022: Homework 4
1. According to the Brønsted-Lowry theory, label each of the following as an acid or a
base.
(a) HNO2
(b) OCl–
(c) NH2–
(d) NH4+
(e) CH3NH3+
2. For each of the following, identify the acids, bases, conjugate acids, and conjugate
bases.
(a) HOBr + H2O
OBr– + H3O+
(b) HSO4– + H2O
SO42– + H3O+
(c) HS– + H2O
H2S + OH–
(d) C6H5NH3+ + OH–
C6H5NH2 + H2O
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3. With which of the following bases will the ionization of acetic acid (CH3COOH) proceed
the furthest toward complete dissociation? Explain your answer.
(a) H2O
(b) NH3
(c) Cl–
(d) NO3–
4. Calculate [H3O+] and [OH–] for each solution:
(a) 0.00165 M HNO3
(b) 0.0087 M KOH
(c) 0.00213 M Sr(OH)2
(d) 5.8 → 10→4 M HI
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5. What is the pH of a solution obtained when 125 mL of 0.606 M NaOH is diluted to
15.0 L with water?
6. What volume of 6.15 M HCl(aq) is required to exactly neturalize 1.25 mL of 0.265 M
NH3(aq)?
7. A 625 mL sample of an aqueous solution containing 0.275 mol propionic acid (CH3CH2CO2H)
has [H3O+] = 0.00239 M. What is the value of Ka for proprionic acid?
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8. What mass of benzoic acid (C6H5COOH) would you dissolve in 350.0 mL of water to
produce a solution with a pH =2.85?
C6H5COOH + H2O
H3O+ + C6H5COO–
Ka = 6.3 → 10→5
9. What must be the molarity of an aqueous solution of trimethylamine ((CH3)3N) if it
has a pH = 11.12?
(CH3)3N + H2O
(CH3)3NH+ + OH–
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Kb = 6.3 → 10→5
10. What is the percent ionization of ethylamine (C2H5NH2) in a 0.85 M aqueous solution?
11. For 0.045 M H2CO3, a weak diprotic acid, calculate
(a) [H3O+]
(b) [HCO3–]
(c) [CO32–]
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12. The antimalarial drug quinine (C20H24O2N2) is a diprotic base.
(a) Write equations for the ionization equilibria corresponding to pKb1 and pKb2 .
(b) What is the pH of a 1 M solution?
13. Calculate the change in pH that results from adding
(a) 0.100 mol NaNO2 to 1.00 L of 0.100 M HNO2(aq).
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(b) 0.100 mol NaNO2 to 1.00 L of 0.100 M HNO3(aq).
(c) Why are the changes not the same?
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