CHM2045 S13: Exam #3
2013.04.05
NA = 6.02214179 × 1023mol-1
1 atm = 101325 Pa = 760 torr = 1.01325 bar = 101.325 kPa
R = 0.08205821 L∙atm/mol∙K = 8.31447215 J/mol∙K
PV = nRT
n = cV = m/M = PV/RT
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Using the graph below, determine the gas that has the lowest density at STP.
A) B
B) C
C) D
D) A
E) All of the gases have the same density at STP.
2) Which of the following compounds exhibits hydrogen bonding?
A) NH3
B) CH3OCH3
C) CH3Cl
D) HI
3) Nickel has a face-centered cubic structure and has a density of 8.90 g/cm 3. What is its atomic radius?
A) 353 pm
B) 997 pm
C) 249 pm
D) 125 pm
4) An arrangement in which every other layer is identical (ABABABAB) is ________.
A) tetrahedral holes
B) cubic close packing
C) octahedral holes
D) hexagonal close packed
E) cubic face centered
5) Identify the type of solid for ice.
A) ionic solid
B) metallic atomic solid
C) nonbonding atomic solid
D) networking atomic solid
E) molecular solid
A-3
6) Which process from the diagram above consumes the most energy?
A) A → B
B) B → C
C) C → D
D) D → E
E) E → F
7) Which of the following keeps the rate of vaporization unchanged?
A) decreasing temperature
B) decreasing surface area
C) increasing mass of molecule
D) increasing forces between molecules
E) closing container lid
8) A large balloon is initially filled to a volume of 25.0 L at 353 K and a pressure of 2575 mm Hg. What volume
of gas will the balloon contain at 1.35 atm and 253 K?
A) 58.6 L
B) 22.2 L
C) 87.5 L
D) 11.4 L
E) 45.0 L
A-4
Use the diagram below to answer the following questions.
9) The solid and liquid phases can exist in equilibrium along line
A) CB.
B) AC.
C) CD.
10) The normal boiling point of this substance is approximately
A) 140°C.
B) 25°C.
C) 350°C.
D) BD.
D) 300°C.
11) Which of the following statements is TRUE?
A) The larger a molecule, the faster it will effuse.
B) For a given gas, the lower the temperature, the faster it will effuse.
C) Particles of different masses have the same average speed at a given temperature.
D) At very high pressures, a gas will occupy a larger volume than predicted by the ideal gas law.
E) None of the above statements are true.
12) When a narrow diameter glass tube is inserted into a body of water, water rises in the tube and its surface
inside is concave upwards. Which statement, concerning the strength of the intermolecular forces between
glass and water molecules compared to those between water molecules, is accurate?
A) The forces of attraction between the glass and water are stronger than those in water.
B) Intermolecular forces are irrelevant to this situation.
C) The forces of attraction between the glass and water are weaker than those in water.
D) The forces of attraction between the glass and water are the same as those in water.
13) The critical temperature and pressure of CS2 are 279°C and 78 atm, respectively. At temperatures above
279°C and pressures above 78 atm, CS2 can only occur as a __________.
A) liquid
B) solid
C) gas
D) liquid and gas
E) supercritical fluid
A-5
14) A 0.465 g sample of an unknown compound occupies 245 mL at 298 K and 1.22 atm. What is the molar mass
of the unknown compound?
A) 81.8 g/mol
B) 12.2 g/mol
C) 38.0 g/mol
D) 33.9 g/mol
E) 26.3 g/mol
15) The volume of 350. mL of gas at 25°C is decreased to 135 mL at constant pressure. What is the final
temperature of the gas?
A) 65°C
B) 9.6°C
C) 500°C
D) -158°C
16) Which of the following compounds will behave LEAST like an ideal gas at low temperatures?
A) F 2
B) He
C) N2
D) H2
E) SO2
17) What pressure would a gas mixture in a 10.0 L tank exert if it were composed of 48.5 g He and 94.6 g CO 2 at
398 K?
A) 39.6 atm
B) 7.02 atm
C) 32.6 atm
D) 58.7 atm
18) Which of the following gases has the lowest average speed at 25°C?
A) SO2
B) C3H8
C) Kr
E) 46.6 atm
D) CH3NH2
19) Which of the following samples will have the greatest volume at STP?
A) 22 g He
B) 22 g CO
C) 22 g O 2
D) 22 g Cl 2
E) All of these samples would have the same volume at STP.
20) Choose the molecule or compound that exhibits dispersion forces as its strongest intermolecular force.
A) NaCl
B) Cl2
C) HF
D) CO
E) All of these have intermolecular forces stronger than dispersion.
21) 2.538 L of pure oxygen gas are collected at exactly one atmosphere of pressure at 25.00°C over water. If the
vapor pressure of water at this temperature is 23.8 torr, what is the mole fraction of the water in the gas
sample?
A) 0.0304
B) 0.969
C) 0.0313
D) 0.970
E) 0.0530
22) Which one of the following derivatives of ethane has the highest boiling point?
A) C2Br6
B) C2H6
C) C2F 6
D) C2Cl6
23) Which of the following is most likely to have the highest viscosity at 25°C?
A) C8H18
B) C2H5NH2
C) HOCH2CH2OH
A-6
E) C2I6
D) C4H10
24) Which one of the following has a low density?
A) liquid
B) gas
C) solid
D) none of the above
E) all of the above
25) Ethylene glycol has a vapor pressure of 14.9 torr at 373K and 49.1 torr at 398K. Calculate its heat of
vaporization in kJ/mol.
A) 76.3
B) 93.0
C) 23.8
D) 58.9
26) How many grams of KCl(s) are produced from the thermal decomposition of KClO3(s) which produces 50.0
mL of O 2(g) at 25°C and 1.00 atm pressure according to the chemical equation shown below?
2 KClO 3(s) → 2 KCl(s) + 3 O2(g)?
A) 0.167 g
B) 0.304 g
C) 0.102 g
D) 0.152 g
27) The ratio of the rate of effusion of oxygen to an unknown gas is 0.935. What is the other gas?
A) N2
B) Ne
C) F 2
D) Ar
28) Which of the following will cause the volume of an ideal gas to triple in value?
A) Raising the temperature from 25°C to 75°C at constant pressure.
B) Lowering the absolute temperature by a factor of 3 at constant pressure.
C) Lowering the pressure by a factor of 3 while the temperature stays constant.
D) Lowering the absolute temperature by a factor of 3 while increasing the pressure by a factor of 3.
E) Raising the absolute temperature by a factor of 3 while increasing the pressure by a factor of 3.
A-7
Answer Key
Testname: CHM2045 S13 E03 P
1) D
2) A
3) D
4) D
5) E
6) D
7) E
8) E
9) A
10) D
11) D
12) A
13) E
14) C
15) D
16) E
17) E
18) C
19) A
20) B
21) A
22) E
23) C
24) B
25) D
26) C
27) A
28) C
A-8