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Chem 1412 HCC Exam two
Name
1. In the reaction
, _____.
A)
B)
C)
D)
HPO42– is a conjugate acid
HPO42– is a conjugate base
NH3 is an acid
NH4+ is a conjugate base
2. The pH of 2.8 x 10–4 M Ba(OH)2 will be _____.
A) 10.45
B) 3.55
C) 9.86
D) 10.75
3. The hydrogen concentration of a solution having a pH 16 is _____.
A) 1  10 –2 M
B) 1  10 –16 M
C) 0
D) 1  10 –14 M
4. The pOH of a solution is 9.40. Its hydrogen ion concentration is _____.
A) 2.5  10 –3 M
B) 2.5  10 –5 M
C) 1.5  10 –5 M
D) 2.5  10 –9 M
5. The weakest acid below is _____.
A) HCl
B) HClO4
C) HF
D) HNO3
6. Which of the following statements is true with respect to the reaction below?
A) The reaction favors the formation of F–(aq).
B) F– is a stronger base than OH–.
C) Hydrofluoric acid is a weaker acid than water.
D) The reaction favors the formation of HF(aq).
7. 0.056 g of CH3COOH (Ka = 1.8  10–5) is dissolved in enough water to obtain 50.0 mL
of solution. The concentration of H+ in the solution is _____.
A) 1.8  10–4 M
B) 1.8  10–3 M
C) 5.8  10–3 M
D) 5.8  10–4 M
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8. The pH of a 0.30 M solution of a weak base is 10.66. What is the Kb of the base?
A) 4.8  10–10
B) 1.85  10–5
C) 7.0  10–8
D) 7.1  10–7
9. The correct order of the strength of the acids below is _____.
A) H2SeO4 > H2SO4
B) H2SO4 > H2SeO4
C) H3PO4 < H3AsO4
D) HClO > HClO4
10. The pH of a 0.36 M CH3COONa solution will be _____.
A) 8.15
B) 7.00
C) 11.15
D) 9.15
11. An aqueous solution of K2HPO4 will be _____.
A) basic
B) acidic
C) neutral
D) amphoteric
12. An example of an acidic oxide is _____.
A) CaO
B) Al2O3
C) N2O5
13. In the reaction:
A)
B)
C)
D)
Cl– acts as a Lewis acid.
AlCl3 acts as a Lewis base.
Cl– acts as a Lewis base.
AlCl4 –acts as a Lewis acid.
14. Which of the following pairs can not make a buffer solution?
(A) KCN and HCN
(B) Na2SO4 and NaHSO4
(C) NH3 and NH4NO3
(D) NaI/HI
15.The pH of a solution containing 0.40 M CH3COOH and 0.20 M CH3COONa is _____.
A)3.33
B)2.22
C)5.55
D)4.44
16.
In a titration experiment 12.5 mL of 0.500 M H2SO4 neutralized 50.0 mL of NaOH. The
concentration of the NaOH solution is ____.
A)
0.500 M
B)
0.250 M
C)
0.125 M
D)
0.0250 M
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17. For which of the following equilibria does Kc correspond to the acid-ionization constant, Ka, of
HC2O4–?
A) HC2O4–(aq) + H2O(l)
H2C2O4(aq) + OH–(aq)
B) H2C2O4(aq) + H2O(l)
H3O+(aq) + HC2O4–(aq)
C) HC2O4–(aq) + H2O(l)
H3O+(aq) + C2O42–(aq)
D) HC2O4–(aq) + OH–(aq)
C2O42–(aq) + H2O(l)
E) HC2O4–(aq) + H3O+(aq)
H2C2O4(aq) + H2O(l)
18. Which of the following reactions is associated with the definition of Kb?
A)
B)
C)
D)
E)
CN–(aq) + H+(aq)
F–(aq) + H2O(l)
Zn(OH2)62+(aq)
Cr3+(aq) + 6H2O(l)
none of these
HCN(aq)
HF(aq) + OH–(aq)
[Zn(OH2)5OH]+(aq) + H+(aq)
Cr(OH2)63+(aq)
19. For the equilibrium that exists in an aqueous solution of nitrous acid (HNO2, a weak acid), the
equilibrium-constant expression is
A)
K=
.
K=
.
B)
C)
K=
.
D) K = [H+][NO2–].
20. A 0.10 M solution of a weak monoprotic acid has a pH of 3.40 at 25°C. What is the acid-ionization
constant, Ka, for this acid?
A) 1.6  10–6
B) 4.0  10–4
C) 3.4  10–5
D) 1.2  10–3
E) 1.8  10–7
21. What is the solubility product expression for Al(OH)3?
A) Ksp = [Al3+][3OH–]
B) Ksp = 3[Al3+][OH–]3
C) Ksp = [Al3+][OH–]3
D) Ksp = [Al3+][3OH–]3
E) Ksp = [Al3+][OH–]
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22. What is the solubility product expression for Th(IO3)4?
A)
B)
C)
D)
E)
Ksp = [Th4+][4IO3–]4
Ksp = [Th4+][IO3–]
Ksp = [Th][IO3]4
Ksp = [Th4+][IO3–]4
Ksp = [Th4+][IO3–]
23. What is the solubility product expression for Zn3(PO4)2?
A) Ksp = [Zn32+][(PO43–)2]
B) Ksp = [3Zn2+]3[2PO43–]2
C) Ksp = [Zn2+][2PO43–]
D) Ksp = [Zn3+]2[PO42–]3
E) Ksp = [Zn2+]3[PO43–]2
24. The concentration of calcium carbonate in a saturated aqueous solution of the salt at 25°C is
6.71  10 5 M. What is the Ksp of this sparingly soluble salt?
A) 4.50  10 9
B) 1.21  10 12
C) 5.47  10 16
D) 8.19  10 3
E) 4.06  10 2
3
25. . The solubility of strontium carbonate in water at 25°C is 4.50  10 g/L. What is the Ksp of this
sparingly soluble salt?
A) 9.30  10 10
B) 1.13  10 13
C) 2.34  10 17
D) 5.52  10 3
E) 3.12  10 2
26. After mixing an excess PbCl2 with a fixed amount of water, it is found that the equilibrium
concentration of Pb2+ is 1.6  10–2 M. What is Ksp for PbCl2?
A) 4.0  10–6
B) 1.6  10–5
C) 2.5  10–4
D) 4.8  10–2
E) 1.0  10–6
27. What is the hydroxide-ion concentration of a saturated solution of Ni(OH)2? For Ni(OH)2, Example
17.4 Ksp = 2.0  10–15.
A) 2.8  10–3 M
B) 7.9  10–6 M
C) 1.0  10–7 M
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D) 2.7  10–2 M
E) 1.6  10–5 M
28. For which of the following will precipitation be expected?
A) Qc < Ksp
B) Qc = 1
C) Qc = Ksp
D) Qc > Ksp
E) Ksp = 1
29. Which of the following will apply to a saturated solution of an ionic compound?
A) Qc < Ksp
B) Qc > Ksp
C) Qc = Ksp
D) Ksp = 1
E) Qc = 1
30. Suppose 50.00 mL of 2.0  10–6 M Fe(NO3)3 is added to 50.00 mL of 2.0 10–4 M KIO3. Which of
the following statements is true? For Fe(IO3)3, Ksp = 1.0  10–14.
A) A precipitate forms because Qc > Ksp.
B) A precipitate forms because Qc < Ksp.
C) No precipitate forms because Qc < Ksp.
D) No precipitate forms because Qc = Ksp.
E) No precipitate forms because Qc > Ksp.
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Part 11 40 point
1a Calculate the pH of typical adult blood, which has a hydronium ion
−8
concentration of 4.0 × 10 M.
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B Label each species as an acid or base. Identify the conjugate acid-base pairs.
HCO3−(aq) + HF(aq)
HCO3−(aq) + OH−(aq)
H2CO3(aq) + F−(aq)
CO32−(aq) + H2O(l)
2a. Sore−throat medications sometimes contain the weak acid phenol, HC6H5O. A 0.10 M
solution of phenol has a pH of 5.43 at 25°C.
a.
What is the acid−ionization
constant, K , for phenol at 25°C?
a
b.
What is the degree of ionization?
8
9
10
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2b Write the chemical equation for the base ionization of methylamine CH3NH2. Write the Kb
expression for methylamine.
The equation is
CH3NH2(aq) + H2O(l)  CH3NH3+(aq) + OH−(aq)
The Kb expression is
Kb =
[CH 3 NH 3  ] [OH  ]
[CH 3 NH 2 ]
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3a. An experimenter finds that the solubility of barium fluoride is 1.1 g in 1.00 L of
water at 25°C. What is the value of K for barium fluoride, BaF , at this
sp
temperature?
2
13
14
3b Write the equilibrium product for the following compounds
A. Mg(OH)2
B. SrCO3
C. Ba3(PO4)
D. Fe(OH)2
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4a One form of kidney stones is calcium phosphate, Ca3(PO4)2, which has a
26
Ksp of 1.0  10
.
3
2+
8
3
A sample of blood contains 1.0  10 M Ca and 1.0  10 M PO4 ion.
Calculate Qc and predict whether Ca3(PO4)2 will precipitate.