AP Chemistry
Worksheet : Ch. 14 ; obj 23-29
Name :
Date :
_____ 1. What is the conjugate acid of NH3?
a) NH3
c) NH3+
e) NH4OH
+
b) NH2
d) NH4+
_____ 2. The conjugate base of HSO4- is __________.
a) OHc) SO42e) H3SO4+
+
b) H2SO4
d) HSO4
_____ 3. The conjugate acid of HSO4- is ___________.
a) SO42c) HSO4+
e) HSO3+
+
b) H2SO4
d) H
_____ 4. What is the conjugate base of OH-?
a) O2
c) H2O
e) H3O+
2b) O
d) O
_____ 5. The molar concentration of hydronium ion in pure water at 25°C is __________.
a) 0.00
c) 1.0x10-14
e) 7.00
-7
b) 1.0x10
d) 1.00
_____ 6. In basic solution, ___________.
a) [H3O+] = [OH-]
d) [H3O+] = 0M
+
b) [H3O ] > [OH ]
e) [OH-] > 7.00
+
c) [H3O ] < [OH ]
_____ 7. Which one of the following statements regarding Kw is false?
a) pKw is 14.00 at 25°C
b) The value of Kw is always 1.0 x 10-14
c) Kw changes with temperature.
d) The value of Kw shows that water is a weak acid.
e) Kw is known as the ion product of water.
_____ 8. The hydride ion, H-, is a stronger base than the hydroxide ion, OH-. The product(s) of the
reaction of hydride ion with water is/are _________.
a) H3O+ (aq)
d) no reaction occurs
b) OH- (aq) + H2 (g)
e) H2O2 (aq)
+
c) OH (aq) + 2H (aq)
_____ 9. Of the following, ____________ is a weak acid.
a) HF
c) HBr
e) HClO4
b) HCl
d) HNO3
_____ 10. The Ka of a weak acid (HA) is 3.0 x 10-4 at 25°C. What is the % ionization of
hypochlorous acid in a 1.5 M aqueous solution of HA at 25°C?
a) 4.5 x 10-7 %
b) 1.4 %
c) 2.1 x 10-4 %
d) 0.014 %
e) 1.4 x 10-2 %
_____ 11. In which of the following aqueous solutions does the weak acid exhibit the highest
percentage ionization?
a) 0.01 M HC2H3O2 (Ka = 1.8 x 10-5)
b) 0.01 M HNO2 (Ka = 4.5 x 10-4)
c) 0.01 M HF (Ka = 6.8 x 10-4)
d) 0.01 M HClO (Ka = 3.0 x 10-8)
e) These will all exhibit the same percentage ionization.
_____ 12. An acid containing the COOH group is called a ___________.
a) strong acid
c) carboxylic acid
b) carbonaceous
d) double oxoacid
acid
e) carbo-oxo acid
_____ 13. Which one of the following cannot act as a Lewis base?
a) Clc) BF3
b) NH3
d) CN-
e) H2O
14. Write the reaction and the corresponding Kb equilibrium expression for each of the following substances
acting as bases in water.
a. NH3
b. C5H5N
c. a. Aniline, C6H5NH2
15. Use the given Kb values to help order the following bases from strongest to weakest.
NO3- H2O, NH3(Kb = 1.8 x 10-5), CH3NH2(Kb = 4.38 x 10-4)
16. Answer the following questions.
a. Which is the stronger base . NO3- or NH3(KbNH3 = 1.8 x 10-5)?
b. Which is the stronger base H2O or NH3?
c. Which is the stronger base? OH- or NH3?
d. Which is the stronger base NH3 or CH3NH2(Kb = 4.38 x 10-4)
17. Calculate the pH of the following solutions :
a. 0.10 M NaOH
b. 1.0 x 10-10 M NaOH
c. 2.0 M NaOH
d. 0.00040 M Ca(OH)2
18. What are the major species present in 0.150 M solutions of each of the following bases?
a. KOH
b. Sr(OH)2
c. A mixture which is 0.0010 M Ba(OH)2 and 0.020 M RbOH
What is [OH-] and the pH of each of these solutions?
19. Calculate the concentration of an aqueous KOH solution that has pH = 10.50.
20. Calculate the concentration of an aqueous Ca(OH)2 solution that has pH = 13.00.
21. What are the major species present in a 0.150 M NH3(Kb = 1.8 x 10-5) solution. Calculate the [OH-] and the
pH of this solution.
22. For the reaction of hydrazine (N2H4) in water, shown below, Kb is 3.0 x 10-6. Calculate the [OH-] and pH
of a 2.0 M solution of hydrazine in water.
H2NNH2 + H2O ↔ H2NNH3+ + OH-
23. Calculate [OH-], [H+], and pH of 0.20 M solutions of each of the following amines.
a. Triethylamine [(C2H5)3N, Kb = 4.0 x 10-4]
b. Hydroxylamine (HONH2, Kb = 1.1 x 10-8)
24. Calculate the pH of a 0.20 M C2H5NH2 solution (Kb = 5.6 x 10-4)
25. Calculate the percent ionization in each of the following solutions.
a. 0.10 M hydroxylamine (HONH2, Kb = 1.1 x 10-8)
b. 0.10 M methylamine (CH3NH2). (Kb = 4.38 x 10-4)
26. The pH of a 0.016 M solution of p-toluidine (CH3C6H4NH2) in water is 8.60. Calculate Kb.
27. Write out the stepwise Ka reactions for the triprotic acid H3AsO4.
28. Using the Ka values in Table 14.4 and only the first dissociation step, calculate the pH of 0.10 M solutions
of each of the following polyprotic acids.
a. H3AsO4 (Ka1 = 5 x 10–3 Ka2 = 8 x 10–8 Ka3 = 6 x 10–10)
b. H2CO3(Ka1 = 4.3 x 10–7 Ka2 = 5.6 x 10–11)
29. Calculate [H+], [OH-], [H3PO4], [H2PO4-], [HPO42-], and [PO43-] for a 0.100 M solution of H3PO4.
Phosphoric acid
Ka1 = 7.5 x 10–3
Ka2 = 6.2 x 10–8
Ka3 = 4.8 x 10–13
30. Calculate the pH of a 2.0 M H2SO4 solution.(Ka2 = 1.2 x 10-2)
[ NH 4 ][OH ]
15. CH3NH2> NH3>H2O> NO3NH 3
16a. NH3 16b. NH3 16c. OH- 16d. CH3NH2 17a. pH = 13.00 17b. pH = 7.00 17c. pH = 14.30
17d. pH = 10.90 18a. Major species : K+, OH-, H2O [OH-] = 0.150 M, pOH = 0.824, pH = 13.176 18b.
Major species : Sr2+, OH-, H2O [OH-] = 0.300 M, pOH = 0.523, pH = 13.477 18c Major species, Ba2+, Rb+,
OH- and water, [OH-] = 0.022 M, pH = 12.34 19. 3.2 x 10-4 M 20. 0.050 M Ca(OH)2 21. NH3 and H2O
are the major species. [OH-] = 1.6 x 10-3 M, pH = 11.20
22. Major species are H2NNH2 and H2O [OH-]
= 2.4 x 10-3 M, pH = 11.38 23a. [OH-] = 8.9 x 10-3 M, [H+] = 1.1 x 10-12 M, pH = 11.96 23b. [OH-] = 4.7
x 10-5 M, [H+] = 2.1 x 10-10 M, pH = 9.68
24. pH = 12.00 25a. 0.033% 25b. 6.4%
26. Kb =
1.0 x 10-9 28a. pH = 1.7 28b. pH = 3.68 29. [H+] = 0.024 M, [OH-] = 4.2 x 10-13 M, [H3PO4] = 0.076 M,
[H2PO4-] = 0.024 M, [HPO42-] = 6.2 x 10-8 M, and [PO43-] = 1.2 x 10-18 M 30. pH = -0.30
Answers : 14a. NH3 + H2O ↔ NH4+ + OH- Kb 