4) A fixed amount of gas at 25.0 °C occupies a volume of 10.0 L when the pressure is 751 torr. Use Boyle’s
law to calculate the pressure (torr) when the volume is reduced to 7.25 L at a constant temperature of
25.0 °C.
A) 1.04 × 103
B) 0.097
C) 5.44 × 104
D) 544
E) 1.36
5) A fixed amount of gas at 25.0 °C occupies a volume of 8.66 L when the pressure is 629 torr. Use
Charles’s law to calculate the volume (L) the gas will occupy when the temperature is increased to 112 °C
while maintaining the pressure at 629 torr.
A) 9.26
B) 11.2
C) 1.93
D) 6.70
E) 38.8
6) A sample of gas (24.2 g) initially at 4.00 atm was compressed from 8.00 L to 2.00 L at constant
temperature. After the compression, the gas pressure was ________ atm.
A) 4.00
B) 2.00
C) 1.00
D) 8.00
E) 16.0
36
7) A balloon originally had a volume of 4.39 L at 44 °C and a pressure of 729 torr. The balloon must be
cooled to ________ °C to reduce its volume to 3.99 L (at constant pressure).
A) 0.00
B) 15.1
C) -288
D) 288
E) 546
8) If 3.21 mol of a gas occupies 56.2 L at 44 °C and 793 torr, 4.73 mol of this gas occupies ________ L under
these conditions.
A) 14.7
B) 61.7
C) 30.9
D) 82.8
E) 478
9) A gas originally at 27 °C and 1.00 atm pressure in a 3.3 L flask is cooled at constant pressure until the
temperature is 11 °C. The new volume of the gas is ________ L.
A) 0.27
B) 3.1
C) 3.3
D) 3.5
E) 0.24
10) A sample of He gas (2.35 mol) occupies 57.9 L at 300.0 K and 1.00 atm. The volume of this sample is
________ L at 469 K and 1.00 atm.
A) 0.709
B) 41.1
C) 90.5
D) 1.41
E) 57.9
11) A sample of an ideal gas (3.00 L) in a closed container at 25.0 °C and 76.0 torr is heated to 270 °C. The
pressure of the gas at this temperature is ________ torr.
A) 912
B) 138
C) 76.5
D) 39.5
E) 0.0253
12) A helium balloon is filled to a volume of 27.7 L at 300 K. What will the volume of the balloon become
if the balloon is heated to raise the temperature to 392 K?
A) 36.2
B) 21.2
C) 0.0276
D) 0.0472
E) 3,260,000
13) At a temperature of ________ °C, 0.444 mol of CO gas occupies 11.8 L at 839 torr.
A) 379
B) 73.0
C) 14.0
D) 32.0
E) 83.5
14) The pressure exerted by 1.0 mol of gas in a 13 L flask at 22 °C is ________ kPa.
A) 560
B) 190
C) 18
D) 2.4
E) 1.0
15) A 0.325 L flask filled with gas at 0.851 atm and 19 °C contains ________ mol of gas.
A) 0.0116
B) 0.0148
C) 9.42
D) 12.4
E) 80.7
16) A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is
added to the flask. The new pressure is 841 mm Hg and the temperature is now 26 °C. There are now
________ mol of gas in the flask.
A) 1.6
B) 2.3
C) 2.9
D) 3.5
E) 0.28
17) A sample of gas (1.3 mol) occupies ________ L at 22 °C and 3.5 atm.
A) 0.079
B) 0.67
C) 9.0
D) 14
E) 0.032
18) The volume of 0.43 mol of an ideal gas at 365 torr and 97 °C is ________ L.
A) 0.054
B) 7.1
C) 11
D) 27
E) 0.024
19) The volume occupied by 2.3 mol of gas at 35 °C and 2.0 atm pressure is ________ L.
A) 38
B) 29
C) 3.3
D) 0.053
E) 0.026
20) How many moles of gas are there in a 36.3 L container at 25.2 °C and 570.3 mm Hg?
A) 1.11
B) 13.2
C) 0.863
D) 0.0110
E) 16,700
21) How many moles of gas are there in a 53.7 L container at 24.6 °C and 845.9 torr?
A) 2.45
B) 29.6
C) 0.409
D) 0.0241
E) 1860
22) The volume of 1.26 mol of gas at 69.4 kPa and 25.30 °C is ________ L.
A) 45.1
B) 633
C) 3.82
D) 0.445
E) 0.439
23) The density of HCN is ________ g/L at STP.
A) 1.21
B) 329
C) 605
D) 0.829
E) 2.21
24) The density of nitric oxide (NO) gas at 0.970 atm and 34.9 °C is ________ g/L.
A) 0.0384
B) 0.869
C) 1.15
D) 0.339
E) 10.2
25) The density of krypton gas at 0.866 atm and 44.4 °C is ________ g/L.
A) 0.0332
B) 0.359
C) 0.238
D) 2.78
E) 5.57
26) The density of chlorine gas at 1.01 atm and 54.1 °C is ________ g/L.
A) 0.0376
B) 0.375
C) 0.228
D) 1.33
E) 2.67
27) The density of ________ is 1.70 g/L at STP.
A) F2
B) NO
C) CH4
D) Ne
E) CO
28) The density of NO2 in a 4.77 L tank at 738.4 torr and 45.0 °C is ________ g/L.
A) 1.71
B) 1300
C) 12.1
D) 0.0169
E) 8.17
29) The density (in g/L) of CO2 at 1106.2 torr and 56.3 °C is ________.
A) 2.37
B) 1800
C) 13.9
D) 0.0234
E) 0.0538
30) Of the following gases, ________ has density of 0.906 g/L at 315 K and 1.16 atm.
A) Ne
B) Ar
C) Kr
D) Xe
E) He
31) A 0.333-g sample of an unknown pure gas occupies a volume of 0.255 L at a pressure of 1.00 atm and
a temperature of 100.0 °C. The unknown gas is ________.
A) xenon
B) neon
C) krypton
D) helium
E) argon
32) Calcium hydride (CaH2) reacts with water to form hydrogen gas:
CaH2 (s) + 2H2O (l) → Ca(OH)2 (aq) + 2H2 (g)
How many grams of CaH2 are needed to generate 48.0 L of H2 gas at a pressure of 0.995 atm and a
temperature of 32 °C?
A) 56.8
B) 0.954
C) 161
D) 40.1
E) 80.3
33) Given the equation:
C2H6 (g) + O2 (g) → CO2 (g) + H2O (g) (not balanced)
Determine the number of liters of CO2 formed at STP when 270.0 grams of C2H6 is burned in excess
oxygen gas.
34) Given the equation:
C2H6 (g) + O2 (g) → CO2 (g) + H2O (g) (not balanced)
Determine the number of liters of O2 consumed at STP when 60.0 grams of C2H6 is burned.
35) A vessel containing Ne(g) and Ar(g) has a total pressure of 9.78. If the partial pressure of the Neon
(PNe) is 3.78 and the partial pressure of the Argon (PAr) is 6, then the mole-fraction of Ne(g) is _______
and the mole-fraction of Ar(g) is ________.
A) 0.39, 0.61
B) 0.61, 0.39
C) 37, 58.7
D) 0.63, 1.59
E) 2.59, 1.63
36) A vessel contains a mixture of 34.9 grams of H2 (g) and 17.7 grams of CH4. If the total pressure inside
the vessel is measured at 2.92 atm, the partial pressure of H2 (g) must be _____ atm.
A) 2.75
B) 50.5
C) 0.175
D) 53.8
E) 5.53
37) 10.0 grams of argon and 20.0 grams of neon are placed in a 1216.1 ml container at 25.1 °C. The partial
pressure of neon is ________ atm.
A) 19.9
B) 5.03
C) 1.68
D) 20.0
E) 49.1
38) 30.0 grams of argon and 15.0 grams of xenon are placed in a 170.9 ml container at 21.8 °C. The partial
pressure of xenon is ________ atm.
A) 16.1
B) 106
C) 1.20
D) 0.472
E) 228
39) A mixture of Xe, Kr, and Ar has a total pressure of 6.69 atm. What is the mole fraction of Kr if the
partial pressures of Xe and Ar are 1.92 atm and 2.75 atm, respectively.
A) 0.302
B) 0.287
C) 0.411
D) 0.259
E) 0.698
40) Zinc reacts with aqueous sulfuric acid to form hydrogen gas:
Zn (s) + H2SO4 (aq) → Zn SO4 (aq) + H2 (g)
In an experiment, 201 mL of wet H2 is collected over water at 27 °C and a barometric pressure of 765 torr.
How many grams of Zn have been consumed? The vapor pressure of water at 27 °C is 26.74 torr.
A) 4.38 × 106
B) 0.519
C) 519
D) 394
E) 3.94 × 105
41) Zinc reacts with aqueous sulfuric acid to form hydrogen gas:
Zn (s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)
In an experiment, 177 mL of wet H2 is collected over water at 27 °C and a barometric pressure of 766 torr.
The vapor pressure of water at 27 °C is 26.74 torr. The partial pressure of hydrogen in this experiment is
________ atm.
A) 0.972
B) 739
C) 1.01
D) 793
E) 1.04
42) The root-mean-square speed of N2 at 33.5 °C is ________ m/sec.
A) 522
B) 51.9
C) 173
D) 302
E) 16.5
43) The root-mean-square speed of NO2 at 28.4 °C is ________ m/sec.
A) 404
B) 40.2
C) 124
D) 233
E) 12.8
44) According to kinetic-molecular theory, in which of the following gases will the root-mean-square
speed of the molecules be the highest at 200 °C?
A) NH3
B) N2O
C) O2
D) UF6
E) None. The molecules of all gases have the same root-mean-square speed at any given temperature.
10.4 Short Answer Questions
1) The temperature and pressure specified by STP are ________ °C and ________ atm.
2) How many molecules are there in 4.00 L of oxygen gas at 500 °C and 50.0 torr?
3) The volume of HCl gas required to react with excess Ca to produce 11.4 L of hydrogen gas at 1.62 atm
and 62.0 °C is ________ L.
4) What is the density (in g/L) of oxygen gas at 77.0 °C and 700.0 torr?
5) What is the partial pressure (in mm Hg) of neon in a 4.00 L vessel that contains 0.838 mol of methane,
0.184 mol of ethane, and 0.755 mol of neon at a total pressure of 928 mm Hg?
6) The rms speed of methane molecules at 45.0 °C is ________ m/sec.
7) The deviation from ideal behavior of a gas is most evident at ________ and/or low temperature.
8) The van der Waals equation corrects the ideal gas law for the finite volume and ________ of gas
molecules.
1) The main component of air is oxygen.
2) If the temperature is lowered from 60 °C to 30 °C, the volume of a fixed amount of gas will be one half
the original volume.
3) A gas is considered “ideal” if one mole of it in a one-liter container exerts a pressure of exactly 1 atm at
room temperature.
4) Kinetic-molecular theory assumes that attractive and repulsive forces between gas particles are
stronger than those between gas particles and container walls.
5) According to the kinetic-molecular theory, molecules of different gases at the same temperature always
have the same average kinetic energy.
6) The effusion rate of a gas is proportional to the square root of its molar mass.
7) Two deviations of real gases from ideal gases which are treated in the van der Waals equation are finite
molecular volume and non-zero molecular attractions.