41 Questions in General
Chemistry I - Exam 5 | CHEM
121
Chemistry
Liberty University
(LU)
12 pag.
Practice Exam 15-17
1. In a 1.2 M solution of KOH, a strong base, [H3O+] = , and [OH-] = .
a. 1.0
×
10-7 M; 1.0 x10-7 M
b. 8.3 × 10-15 M; 1.0 x10-14 M
c. 8.3 × 10-15 M; 1.2 M
d. 1.2 M; 8.3 × 10-15 M
e. 1.2 M; 1.2 M
2. The process of dissolving is favored if the interactions are weaker than the
interations.
a. solute-solvent; solute-solute and solvent-solvent
b. solvent-solvent; solute-solute and solute-solvent
c. solute-solute and solvent-solvent; solute-solvent
d. solute-solvent and solvent-solvent; solute-solute
e. solute-solute; solute-solvent and solvent-solvent
3. What volume of 0.1060 M NaOH is needed to neutralize a 50.00 mL sample of 0.0950 M HNO3?
a. 55.79 mL
b. 55.19 mL
c. 50.00 mL
d. 44.81 mL
e. 5.19 mL
4. When 1.00 L of 0.45 M acetic acid (pKa = 4.74) is mixed with the exact volume of 0.55 M NaOH required
to convert the acid to its conjugate base, at the endpoint the solution will have a
a. pH < 7.00
b. pH = 7.00
c. pH > 7.00
4
4
4
d. pH < pKa
e. pH = pKa
5. The overall enthalpy change during the process of forming a solution involves three terms: separating solvent
molecules
(
H
solvent),
sep
arati
ng
solute
pa
rti
cles
(
H
solute),
and
forming
new
solute-solvent
assoc
iati
ons
(
H
solu
ti
on).
The
overall
process
of
forming
a
solu
ti
on
is
endothermic
if
a.
|
H
solute
+
H
solvent|
>
|
H
solu
ti
on|.
b.
|
H
solute
+
H
solvent|
=
|
H
solu
ti
on|.
c.
|
H
solute
+
H
solvent|
<
|
H
solu
ti
on|.
d.
H
solute
+
H
solvent
=
0.
e.
H
solu
ti
on
=
0.
6. In this reaction
NH3(aq) + H2O(l) ⇌ NH +(aq) + OH-(aq)
a. NH3 acts as a base and OH- as an acid.
b. H2O acts as an acid and OH- as a base.
c. H2O acts as a base and NH + as an acid.
d. H2O acts as an acid and NH + as a base.
e. NH3 acts as an acid and OH- as a base.
7. If the pH of a solution is raised from 6.27 to 7.57
a. the solution has gone from acidic to basic
b. [H3O+] has decreased by a factor of 20
c. [OH-] has increased by a factor of 20
d. the new [H3O+] = 2.7 x 10-8
e. all of the above
8. A solution with solute concentration less than the solubility is said to be ; solute will dissolve in such
as solution.
a. undersaturated; more
b. undersaturated; no more
c. saturated; more
d. saturated; no more
e. supersaturated; more
9. A 50.00 mL sample of 0.0950 M acetic acid (Ka = 1.8
×
10-5) is being titrated with 0.0848 M NaOH. What is
the pH after 28.00 mL of NaOH has been added?
a. 5.04
b. 4.74
c. 4.44
d. 3.18
e. 3.06
10. Which of the following is a conjugate acid-base pair?
a. CH3COO- and H2O
b. H3O+ and OH-
c. CH3COOH and CH3COO-
d. CH3COOH and H3O+
e. CH3COOH and OH-
11. Increasing the temperature of water containing a dissolved gas will almost always
a. decrease the solubility of the gas
b. increase the solubility of the gas
c. have no effect on the solubility of the gas
d. decrease the solubility of the gas only if the gas is one that naturally occurs in the atmosphere
e. increase the solubility of the gas only if the gas is one that naturally occurs in the atmosphere
12. A coffee sample had a pH of 3.52. This corresponds to [H3O+] =
a. 3.3 x 10-11 M.
b. 3.0 x 10-4 M.
c. 5.2 x 10-4 M.
d. 5.2 x 10-3 M.
e. 3.3 x 10-3 M.
13. For inorganic compounds, solubility in water is
a. always increased by an increase in temperature
b. always decreased by an increase in temperature
c. usually decreased by an increase in temperature
d. usually increased by an increase in temperature
e. not affected by a change in temperature
14. The pressure inside a soda bottle is two atmospheres (1520 mm Hg). If exactly half this pressure is generated
by CO2, what is the solubility of carbon dioxide in a 2 L bottle of root beer at 40 oC? The Henry's Law constant
for CO2 is 4.45
×
10-5 M/mm Hg.
a. 2.93 × 10-8 M
b. 9.90 × 10-5 M
c. 1.78
×
10-3 M
d. 0.0338 M
e. 0.0676 M
15. Which combination of solutions is the best choice for making a buffer solution?
a. equal volumes of 1 M acetic acid and 0.005 M sodium acetate
b. equal volumes of 0.5 M nitric acid and 0.5 M sodium hydroxide
c. equal volumes of 0.1 M formic acid and 0.1 M sodium formate
d. equal volumes of 0.1 M sulfuric acid and 0.001 M sodium sulfate
e. equal volumes of 0.05 M hydrochloric acid and 0.075 ammonium chloride
16. A buffer solution is 0.080 M in lactic acid (Ka = 1.8
×
10-4) and 0.070 M in sodium lactate.
The pH of the solution is
a. 2.86.
b. 3.68.
c. 3.80.
d. 4.18.
e. 4.62.
17. Considering true solutions, colloidal dispersions, and suspensions, which of the following is true?
a. true solutions and colloidal dispersions are not filterable
b. all have particles in the range 2-2000 nm
c. all contain particles that will settle out on standing if you wait long enough
d. all contain colloidal solids
e. all of the above are correct
4
4
4
4
4
4
3
18. Which of the following statements is not correct?
a. a Lewis acid is a substance that can accept a pair of electrons to form a new bond
b. a Lewis base is a substance that can donate a pair of electrons to form a new bond
c. Al(OH)3 is an amphoteric substance that can form either a positive or negative ion
d. Neutral molecules cannot act as Lewis acids
e. Ag(NH3)2+ is a complex ion, formed from a Ag+ ion (Lewis acid) and two NH3 molecules (Lewis bases)
-
19. Write the acid ionization constant expression for the ionization of the hydrogen sulfate ion, HSO 4 , in aqueous
solution.
[ SO
2−
][ H O
+
]
a. Ka =
[ HSO
−
]
[H SO ][H O+]
K
a
=
b.
2
4
3
[HSO- ]
[HSO- ][H O]
Ka =
[H SO
4
2
][H
O+]
c. 2 4
[H SO
3
][OH-]
K
a
=
d.
2
4
[HSO- ]
Ka =[HSO- ][H O]
2
[SO
2-
]
[H
e. 3O+]
20. A buffer solution is one which
a. contains more than the expected amount of solute for a particular temperature and is therefore
unstable.
b. contains the maximum amount of solute possible for a particular temperature.
c. changes color upon addition of strong base.
d. contains an equal number of hydronium and hydroxide ions.
e. resists changes in pH upon addition of acid or base.
4 a
21. A concentrated antifreeze solution contains 580 g ethylene glycol mixed with 540 g of water. The weight
percent of water in this solution is
a. 27.0 %
b. 48.2%
c. 51.8 %
d. 93.1 %
e. 107%
-2-
22. Consider a buffer solution made up of H2PO 4 and HPO 4. For H2PO -, K = 6.2
×
10-8. What mole ratio of
2-
HPO 4
-
to H2PO 4 will give a pH of 7.35?
a. 0.14 to 1
b. 0.72 to 1
c. 1 to 1
d. 1.4 to 1
e. More information is needed to answer this question.
23. The pH of a 0.50 M solution of the weak acid HA is 4.76. The value of Ka is
a. 6.0
×
10-10
b. 1.7 × 10-5
c. 3.5 × 10-5
d. 7.6 × 10-4
e. 9.24
24. The concentration unit one part per billion ( one ppb) is equivalent to one of solute per of
solution.
a. mg; g
b.
g; g
c. mg; kg
d.
g; kg
e. ng; kg
25. What is the smallest amount of solid NaOH shown that will exceed the buffer capacity of 500 mL of a buffer
that is 0.40 M in acetic acid and 0.15 M in sodium acetate.
(Ka for acetic acid = 1.8 × 10-
5.)
a. 5.69 g
b. 5.16 g
c. 4.74 g
d. 4.31 g
e. 3.00 g
26. Which of the following salts forms a basic solution when dissolved in water?
a. NH4ClO4
b. CH3NH3Cl
c. NaClO4
d. LiCH3COO
e. NaCl
27. The poison strychnine is a weakly basic compound with Kb = 1.8
×
10-6. What is the pH of a 0.058 M
solution of strychnine?
a. 3.49
b. 7.30
c. 8.26
d. 10.51
e. 12.76
28. In an acidic solution at 25oC, which of the following is not true?
a. [H3O+] > 1.0 x 10-7
b. [H3O+] > [OH-]
3
4
c. [OH-] < 1.0 x 10-7
d. [H3O+][OH-] > 1.0 x 10-7
e. [H O+][OH-] < 1.0 x 10-7
29. Isotonic saline solution has a mass % NaCl concentration of 0.900 %. Assuming its density is 1.00 g/mL, what is
its molarity?
a. 9.00 x 10-3 M
b. 0.0900 M
c. 0.154 M
d. 0.900 M
e. 1.80 M
30. A solution is not neutral. Which one of these statements is true?
a. [H3O+] = 1.0 x 10-7 M
b. [H3O+] = [OH-]
c. [H3O+][OH-] = 1.0 x 10-7
d. [OH-] = 1.0 x 10-7 M
e. [H3O+][OH-] = 1.0 x 10-14
31. A 0.1 M solution of Na2SO4 contains
a. 9.6 x 103 mg/L SO 2-
b. 4.6 x 106 ppb Na+
c. 14.2. g/L sodium sulfate
d. 0.3 mol/L ions
e. all of the above are correct
32.
What
is
the
vapor
pressure
of
a
45.0
%
solu
ti
on
of
glucose,
C6H12O6,
at
90.0
C,
given
that
the
vapor
pressure
of pure water at that temperature is 526 mm Hg?
a. 486 mm Hg
b. 289 mmHg
c. 237 mm Hg
d. 78.2 mm Hg
e. 39.8 mm Hg
33. Because water can act as a Bronsted-Lowry acid or base, it is said to be .
a. amphiphilic
b. amphihydrous
c. amphiphobic
d. amphiprotic
e. amphoteric
34. Calculate the boiling point of a mixture where 95.0 g of formic acid, H 2CO2, is dissolved in 250 g of acetic acid.
Ace
ti
c
acid
has
a
Kb
of
2.93
C/m
and
boils
at
118
C.
Assume
that
formic
acid
does
not
ionize
when
dissolved
in
acetic acid, and that formic acid is non-volatile.
a.
118
C
b.
142
C
c.
136
C
d.
115
C
e.
126
C
35. Calculate the pH of a 0.051 M solution of sodium lactate. The Ka for lactic acid is
1.4
×
10-4.
a. 1.29
b. 2.57
c. 8.28
d. 11.43
e. 12.71
36. Which compound would not be used as an antacid for the treatment of heartburn?
a. KOH
b. Al(OH)3
c. Mg(OH)2
d. NaHCO3
e. CaCO3
37. Osmotic pressure is the
a. pressure that must be applied to a solution in order to prevent osmosis from the pure solvent.
b. pressure that must be applied to a solution in order to cause osmosis to occur from the pure solvent.
c. correction factor applied when a sample of gas is collected by water displacement.
d. increase in vapor pressure when a solution is compared to a pure solvent.
e. decrease in vapor pressure when a solution is compared to a pure solvent.
38.
An
aqueous
solu
ti
on
at
27
C
contains
3.6
g
of
a
protein
in
a
200
mL
sample.
The
osmo
ti
c
pressure
is
0.0203
atm. What is the molar mass of the protein?
a. 21.8 g/mol
b. 78.6 g/mol
c. 8.70 x 102 g/mol
d. 2.03 × 103 g/mol
e. 2.18 × 104 g/mol
39. In terms of acid strength, which of the following does not belong with the others?
a. HNO2
b. HClO4
c. HCOOH
d. HF
e. H2SO3
40. Organic compounds classified as acids often have the formula
a. R-CH3.
b. R-CHO.
c. R-COOH.
d. R-NH2.
e. R-OH.
41. Organic compounds classified as bases often have the formula
a. R-CHO. b. CH3-(CH2)n-CH3. c. R-COOH.
d. R-NH2. e. R-OH.
