Name: Exam 3 Chemistry 65 Summer 2015 Score: Instructions: Clearly circle the one best answer 1. The main interactions between molecules of iodine I2 are examples of
A) ionic bonds.
B) covalent bonds.
C) hydrogen bonds.
D) dipole-dipole interactions.
E) dispersion forces.
Answer: E
2. According to the kinetic theory of gases, a gas can be compressed much more than a liquid or solid
because
A) a gas is composed of very small particles.
B) the particles of a gas are very far apart.
C) gas particles move rapidly.
D) gas particles do not attract or repel one another.
E) gas particles move faster when the temperature increases.
Answer: B
3. A 5.00-L tank contains helium gas at 1.50 atm. What is the pressure of the gas in mmHg?
A) 1.50 mmHg
B) 507 mmHg
C) 760 mmHg
D) 1140 mmHg
E) 7.5 mmHg
Answer: D
4. What unit of temperature is used in gas law calculations?
A) degrees Fahrenheit
B) degrees Celsius
C) Kelvin
D) either degrees Celsius or degrees Fahrenheit
E) either degrees Celsius or Kelvin
Answer: C
5. As the temperature of a gas increases, the density of the gas will __________.
A) increase
B) decrease
C) remain constant
Answer: B
6. The boiling point of water at sea level is 100 °C. At higher altitudes, the boiling point of water will
be
A) lower, because temperatures are lower.
B) lower, because the atmospheric pressure is lower.
C) higher, because the altitude is greater.
D) higher, because there are fewer water molecules in the air.
E) the same, because water always boils at 100 °C.
Answer: B
7. Vapor pressure can be described as
A) the temperature at which bubbles of vapor appear in a liquid.
B) the pressure exerted on the Earth by the particles in the air.
C) the temperature at which the vapor pressure of a liquid equals atmospheric pressure.
D) the pressure exerted by a gas above the surface of its liquid.
E) the pressure within the lungs during inhalation.
Answer: D
8. At STP, what is the volume of 4.50 moles of nitrogen gas?
A) 167 L
B) 3420 L
C) 101 L
D) 60.7 L
E) 1230 L
Answer: C
9. According to Avogadro's law,
A) the volume of a gas is inversely related to the number of moles at constant temperature and
pressure.
B) the volume of a gas is inversely related to the number of moles at standard temperature and
pressure.
C) the volume of a gas depends only on the temperature and pressure.
D) the volume of a gas depends only on the number of moles in the sample.
E) the volume of a gas is directly related to the number of moles at constant temperature and pressure.
Answer: E
10. Which of the following molecules can form hydrogen bonds?
A) CH4 B) NaH
C) NH3
D) BH3
E) HI
Answer: C
11. When solutions of KCl and Pb(NO3)2 are mixed, a precipitate forms. Which of the following is the
balanced equation for the double replacement reaction that occurs?
A) KCl(aq) + Pb(NO3)2(aq) → KNO3(aq) + PbCl2(s)
B) KNO3(aq) + PbCl2(s) → KCl(aq) + Pb(NO3)2(aq)
C) K+(aq) + NO3-(aq) → KNO3(aq)
D) 2KCl(aq) + Pb(NO3)2(aq) → 2 KNO3(aq) + PbCl2(s)
E) KCl(aq) + Pb(NO3)2(aq) → KNO3(aq) + PbCl(s)
Answer: D
12. When solutions of NaCl and AgNO3 are mixed,
A) a precipitate of AgCl forms.
B) a precipitate of NaNO3 forms.
C) no precipitate forms.
D) precipitate of NaNO3 and AgCl form.
E) a precipitate of AgCl2 forms.
13. According to Henry's law, the solubility of a gas in a liquid
A) decreases as the gas pressure above the liquid increases.
B) increases as the gas pressure above the liquid increases.
C) remains the same as the temperature increases.
D) depends on the liquid polarity.
E) depends on the liquid density.
Answer: B
14. What is the molarity of a solution that contains 17 g of NH3 in 0.50 L of solution?
A) 34 M
B) 2.0 M
C) 0.50 M
D) 0.029 M
E) 1.0 M
Answer: B
15. What volume of 0.10 M NaOH can be prepared from 250. mL of 0.30 M NaOH?
A) 0.075 L
B) 0.25 L
C) 0.75 L
D) 0.083 L
E) 750 L
Answer: C
16. When the combined gas law is rearranged to solve for V2, the following is the correct expression:
V2=
A) T2 T1 V1/P2P1
B) P1V1T2/P2T1
C) P1V1T1/P2T2
D) P2T2/P2V1T1
E) P1V1/T1 - P2/T2
Answer: B
17. What is the mass of a sample of O2 gas, which has a pressure of 740. mmHg, at a temperature of
25 °C, in a volume of 250. mL?
A) 0.318 g
B) 3.82 g
C) 201 g
D) 292 g
E) 320. g
Answer: A
18. A cyclopropane-oxygen mixture is used as an anesthetic. If the partial pressure of cyclopropane in
the mixture is 330 mmHg and the partial pressure of the oxygen is 1.0 atm, what is the total pressure of
the mixture in torr?
A) 330 torr
B) 430 torr
C) 760 torr
D) 1.4 torr
E) 1100 torr
Answer: E
19. When KCl dissolves in water
A) the Cl- ions are attracted to dissolved K+ ions.
B) the Cl- ions are attracted to the partially negative oxygen atoms of the water molecule.
C) the K+ ions are attracted to Cl- ions on the KCl crystal.
D) the K+ ions are attracted to the partially negative oxygen atoms of the water molecule.
E) the K+ ions are attracted to the partially positive hydrogen atoms of the water molecule.
Answer: D
20. When some of the sugar added to iced tea remains undissolved at the bottom of the glass, the
solution is
A) dilute.
B) polar.
C) nonpolar.
D) saturated.
E) unsaturated.
Answer: D
21. What volume of a 2.00 M KCl solution is required to prepare 500. mL of a 0.100 M KCl solution?
A) 0.0400 mL
B) 25.0 mL
C) 2.00 mL
D) 1.00 × 104 mL
E) 5.00 × 102 mL
Answer: B
22. Use the reaction: 2AgNO3(aq) + H2SO4(aq) → Ag2SO4(s) + 2H2O(l)
What volume of 0.123 M AgNO3(aq) is needed to form 0.657 g of Ag2SO4(s)?
A) 34.2 L
B) 17.1 mL
C) 34.2 mL
D) 10.7 mL
E) 53.4 mL
Answer: C
23. The strongest interactions between molecules of hydrogen chloride are
A) ionic bonds.
B) covalent bonds.
C) hydrogen bonds.
D) dipole-dipole interactions.
E) dispersion forces.
Answer: D
24. The strongest interactions between molecules of ammonia ( NH3 ) are
A) ionic bonds.
B) hydrogen bonds.
C) polar covalent.
D) dipole-dipole.
E) dispersion forces.
Answer: B
25. The atmospheric pressure in Denver, CO is 633 mmHg. What is this pressure in atm?
A) 1.20 atm
B) 633 atm
C) 0.833 atm
D) 1.00 atm
E) 127 atm
Answer: C
26 The air pressure on a rainy day is usually __________ air pressure on a sunny day.
A) higher than
B) lower than
C) the same as
Answer: B
27. A balloon is filled with helium gas. For the question that follows, select the letter of the balloon
diagram that corresponds to the given change in conditions.
The temperature is changed from 50 °C to -150 °C at constant pressure.
A) A
B) B
C) C
D) A and B
E) B and C
Answer: A
28. If 0.795 mol of ammonia gas occupies 24.5 L at 0.853 atm, what is the Celsius temperature? (R =
0.0821 atm•L/mol•K)
A) -71 °C
B) 5 °C
C) 47 °C
D) 278 °C
E) 320 °C
Answer: C
29. What happens to the pressure of a gas if the number of molecules increases twofold (volume and
temperature remain constant)?
A) The pressure decreases twofold.
B) The pressure decreases fourfold.
C) The pressure increases twofold.
D) The pressure increases fourfold.
E) The pressure remains constant.
Answer: C
30. Which of the following is NOT part of the kinetic theory of gases?
A) A gas is composed of very small particles.
B) There is very little empty space in a gas.
C) Gas particles move rapidly.
D) Gas particles do not attract or repel one another.
E) Gas particles move faster when the temperature increases.
Answer: B