Deck 11: Gases and Their Properties

Question 1

A glass column is filled with mercury and inverted in a pool of mercury. The mercury column stabilizes at a height of 736 mm above the pool of mercury. What is the pressure of the atmosphere?

A) 1.03 atm
B) 0.646 atm
C) 463 atm
D) 0.968 atm
E) 0.736 atm

Answer 1

0.968 atm

Question 2

A flexible vessel is filled to a certain pressure with 93.00 L of gas. Under conditions of constant temperature and moles of gas, how does the volume of the gas change when the pressure of the gas is tripled?

A) The volume decreases by a factor of three.
B) The volume decreases by a factor of four.
C) The volume remains the same.
D) The volume decreases by a factor of two.
E) The volume increases by a factor of three.

Answer 2

The volume decreases by a factor of three.

Question 3

Which of the following statements is true of Charles's law, $\frac { V } { T } = k$ ?

A) The volume of a gas varies proportionally with pressure.
B) The volume of a gas sample varies directly with the absolute temperature.
C) All gas samples of the same volume at STP contain the same number of atoms.
D) The pressure of a gas sample varies inversely with volume.
E) All gas samples of the same volume at STP contain the same number of molecules.

Answer 3

The volume of a gas sample varies directly with the absolute temperature.

Question 4

A flexible container is filled with 49.00 L of gas at 333 Κ. Under conditions of constant pressure and moles of gas, what is the temperature of the gas when the volume is doubled?

A) 666.000 K
B) 167 K
C) 0.00600 K
D) 333.2 K
E) 1.22 K

Question 5

The local weather forecaster reports that the current barometric pressure is 29.2 inches of mercury. What is the current pressure in atmospheres?

A) 1 atm
B) 9.89 atm
C) 1.00 atm
D) 3.89 atm
E) 874 atm

Question 6

A particular gas exerts a pressure of 681 mm Hg. What is this pressure in units of bar? (1 atm = 760 mm Hg = 101.3 kPa = 1.013 bar)

A) 5.11 × 10⁵ bar
B) 5.24 × 10⁵ bar
C) 690 bar
D) 0.884 bar
E) 0.908 bar

Question 7

It is possible to make a barometer using a liquid other than mercury. What would be the height (in meters) of a column of dichloromethane at a pressure of 0.790 atm, given that 0.790 atm is equal to a 0.600 m column of mercury and the densities of mercury and dichloromethane are 13.5 g/cm³ and 1.33 g/cm³, respectively.

A) 6.09 m
B) 0.164 m
C) 0.0592 m
D) 0.799 m
E) 1.25 m

Question 8

A flexible vessel contains 53 L of gas where the pressure is 1.1 atm. What will the volume be when the gas is compressed to a pressure of 0.91 atm, the temperature remaining constant?

A) 0.016 L
B) 44 L
C) 53 L
D) 0.038 L
E) 64 L

Question 9

A certain person has a body temperature of 309 K. On a cold day, what volume of air at 276 K must this person with a lung capacity of 3.1 L breathe in to fill his lungs?

A) 3.47 L
B) 2.77 L
C) 2.92 L
D) 5.54 L
E) none of these

Question 10

A sample of helium gas occupies 17.9 L at 23°C and 0.956 atm. What volume will it occupy at 40°C and 1.20 atm?

A) 23.8 L
B) 24.8 L
C) 13.5 L
D) 15.1 L
E) 18.1 L

Question 11

Absolute zero is the point at which

A) a straight-line graph of V versus T (°C) intersects the origin.
B) a straight-line graph of 1/V versus P at constant T intersects the origin.
C) gaseous helium liquefies.
D) a straight-line graph of V versus 1/P at constant T intersects the origin.
E) a straight-line graph of V versus T (K) intersects the origin.

Question 12

A particular gas exerts a pressure of 5.35 × 10⁴ Pa. What is this pressure in units of atmospheres? (1 atm = 760 mm Hg = 101.3 kPa = 1.013 bar)​

A) 0.528 ​atm
B) 5.28 × 10⁹ atm
C) 0.542 ​atm
D) 0.535 ​atm
E) 5.42 × 10⁹ atm

Question 13

A particular gas exerts a pressure of 2.97 bar. What is this pressure in units of atmospheres? (1 atm = 760 mm Hg = 101.3 kPa = 1.013 bar)

A) 3.01 atm
B) 2.23 × 10³ atm
C) 2.29 × 10³ atm
D) 2.93 atm
E) 2.97 atm

Question 14

Which of the following is the largest value of pressure?

A) 72539 Pa
B) 485 mm Hg
C) 12.6 psi
D) 0.677 atm
E) 14.9 in Hg

Question 15

A gas sample is heated from −20.0°C to 57.0°C and the volume is increased from 2.00 L to 4.50 L. If the initial pressure is 0.150 atm, what is the final pressure?

A) 0.0511 atm
B) -0.190 atm
C) 0.440 atm
D) 0.259 atm
E) 0.0869 atm

Question 16

A physics experiment is conducted at a pressure of 13.8 kPa. What is this pressure in mmHg? (1 atm = 760 mm Hg = 101.3 kPa)

A) 18.2 mmHg
B) $1.82 \times 10 ^ { - 2 }$ mmHg
C) 1.84 mmHg
D) 104 mmHg
E) $1.38 \times 10 ^ { 4 }$ mmHg

Question 17

A gas sample is held at constant pressure. The gas occupies 3.62 L of volume when the temperature is 21.6°C. Determine the temperature at which the volume of the gas is 3.47 L.

A) 295 K
B) 283 K
C) 20.7 K
D) 556 K
E) 307 K

Question 18

A sample of methane, CH₄, occupies a volume of 230.0 mL at 25°C and exerts a pressure of 900.0 mmHg. If the volume of the gas is allowed to expand to 680.0 mL at 298 K, what will be the pressure of the gas?

A) 2660 mmHg
B) 3630 mmHg
C) 304.4 mmHg
D) 0.01113 mmHg
E) 450.0 mmHg

Question 19

A balloon has a volume of 2.52 liters at 24.0°C. The balloon is heated to 48.0°C. Calculate the new volume of the balloon.

A) 2.52 L
B) 2.72 L
C) 2.33 L
D) 5.04 L
E) 1.26 L

Question 20

A flexible vessel contains 49.00 L of gas at a pressure of 2.81 atm. Under the conditions of constant temperature and constant number of moles of gas, what is the pressure of the gas when the volume of the vessel is quadrupled?

A) 0.702 atm
B) 11.2 atm
C) 1.42 atm
D) 2.81 atm
E) 0.0351 atm

Question 21

Which of the following gases has the greatest density at 35 °C and 450 mm Hg?

A) CH₄
B) Ar
C) N₂
D) Cl₂
E) C₃H₈

Question 22

A gas occupying a volume of 1.50 L exerts a pressure of 700 mmHg at 200°C. Which mathematical expression gives the correct pressure at 9.00 L and 350°C?

A) $700 \mathrm { mmHg } \times \frac { 1.50 \mathrm {~L} } { 9.00 \mathrm {~L} } \times \frac { 473 \mathrm {~K} } { 623 \mathrm {~K} }$
B) $700 \mathrm { mmHg } \times \frac { 1.50 \mathrm {~L} } { 9.00 \mathrm {~L} } \times \frac { 623 \mathrm {~K} } { 473 \mathrm {~K} }$
C) $700 \mathrm { mmHg } \times \frac { 9.00 \mathrm {~L} } { 1.50 \mathrm {~L} } \times \frac { 473 \mathrm {~K} } { 623 \mathrm {~K} }$
D) $700 \mathrm { mmHg } \times \frac { 9.00 \mathrm {~L} } { 1.50 \mathrm {~L} } \times \frac { 623 \mathrm {~K} } { 473 \mathrm {~K} }$
E) $700 \mathrm { mmHg } \times \frac { 9.00 \mathrm {~L} } { 1.50 \mathrm {~L} } \times \frac { 350 ^ { \circ } \mathrm { C } } { 200 ^ { \circ } \mathrm { C } }$

Question 23

The temperature of a specific amount of gas in a sealed container changes from 40.0°C to 80.0°C. If the volume remains constant, the pressure will change from 755 mmHg to ___.

A) 755 mmHg
B) 378 mmHg
C) 1510 mmHg
D) 669 mmHg
E) 851 mmHg

Question 24

A 2.00-L glass soda bottle filled only with air is tightly capped at 19°C and 732.0 mmHg. If the bottle is placed in water at 89°C, what is the pressure in the bottle?

A) 156 mmHg
B) 907 mmHg
C) 3430 mmHg
D) 590 mmHg
E) 474 mmHg

Question 25

A balloon is filled with He gas to a volume of 2.10 L at 35 °C. The balloon is placed in liquid nitrogen until its temperature reaches -196 °C. Assuming the pressure remains constant, what is the volume of the cooled balloon?

A) −0.375 L
B) 0.375 L
C) 0.525 L
D) 0.00909 L
E) 8.40 L

Question 26

A 45.0 L gas cylinder contains 988 g He at 23 °C. What is the pressure inside the cylinder? (R = 0.08206 L⋅atm/mol⋅K)

A) 10.4 atm
B) 41.4 atm
C) 101 atm
D) 133 atm
E) 533 atm

Question 27

What volume of gaseous silane, SiH₄, has the same moles of gas as 9.00 L of helium gas at the same temperature and pressure?

A) 54.0 L
B) 1.50 L
C) 9.00 L
D) 1.80 L
E) 45.0 L

Question 28

The volume of a sample of gas measured at 50.0°C and 1.00 atm pressure is 2.00 L. What must the final temperature be in order for the gas to have a final volume of 3.00 L at 1.00 atm pressure?

A) 211.5°C
B) 75.0°C
C) -198.0°C
D) 33.3°C
E) -57.7°C

Question 29

What volume does 49.0 g of N₂ gas occupy at STP? (R = 0.08206 L⋅atm/mol⋅K)

A) 78 L
B) 2 L
C) 39 L
D) 61 L
E) None of these

Question 30

Gaseous chlorine is held in two separate containers at identical temperatures and pressures. The volume of container 1 is 1.30 L, and it contains 6.70 mol of the gas. The volume of container 2 is 2.75 L. How many moles of the gas are in container 2?

A) 14.2 mol
B) 24.0 mol
C) 0.534 mol
D) 3.17 mol
E) None of these

Question 31

The pressure of O₂ in a 15.0 L flask is 322 mm Hg at 44 °C. What mass of O₂ is in the flask? (R = 0.08206 L⋅atm/mol⋅K)

A) 0.244 g
B) 5.80 g
C) 7.82 g
D) 15.2 g
E) 56.3 g

Question 32

You have a 30.0 L cylinder of helium at a pressure of 132 atm and a temperature of 19 °C. The He is used to fill balloons to a volume of 1.80 L at 745 mm Hg and 27 °C. How many balloons can be filled with He? Assume that the cylinder can provide He until its internal pressure reaches 1.00 atm (i.e., there are 131 atmospheres of usable He in the cylinder).

A) 1.90 × 10²
B) 1.06 × 10²
C) 4.13 × 10³
D) 7.41 × 10³
E) 2.29 × 10³

Question 33

What volume of oxygen will react with 21 mL of ethanol, assuming the gases are present at the same temperature and pressure? 2 CH₃CH₂OH(g) + 6 O₂(g) → 4 CO₂(g) + 6 H₂O(g)

A) 7.0 mL
B) 14 mL
C) 21 mL
D) 42 mL
E) 63 mL

Question 34

A 26.4-L sample of nitrogen at 7.50 atm and 24°C is simultaneously expanded to 58.4 L and heated to 35°C. What is the new pressure of the gas?

A) 4.94 atm
B) 3.52 atm
C) 141 atm
D) 198 atm
E) 3.27 atm

Question 35

If 0.357 g of CH₄ gas is introduced into an empty 1.75 L flask at 25 °C, what will be the pressure inside the flask? (R = 0.08206 L⋅atm/mol⋅K)

A) 0.952 atm
B) 0.261 atm
C) 0.311 atm
D) 0.419 atm
E) 4.99 atm

Question 36

Equal volumes of propane, C₃H₈, and carbon monoxide, CO, at the same temperature and pressure have the same ____.

A) chemical properties.
B) number of atoms.
C) average molecular speed.
D) density.
E) number of molecules.

Question 37

What is the pressure of a 52.5-L gas sample containing 1.57 mol of gas at 93.2°C? (R = 0.0821 L • atm/(K • mol), 1 atm = 760 mmHg)

A) 1.74 × 10² mmHg
B) 1.18 × 10^-3 mmHg
C) 0.899 mmHg
D) 6.83 × 10² mmHg
E) 8.45 × 10² mmHg

Question 38

What volume is occupied by 35.0 g of C₂H₂ at 471 mm Hg and 21 °C? (R = 0.08206 L⋅atm/mol⋅K)

A) 29.0 L
B) 52.3 L
C) 3.74 L
D) 20.1 L
E) 0.0689 L

Question 39

You have 34.5 g of O₂ gas in a container with twice the volume as one with CO₂ gas. The pressure and temperature of both containers are the same. Calculate the mass of carbon dioxide gas you have in the container.

A) 0.539 g
B) 47.4 g
C) 2.16 g
D) 23.7 g
E) none of these

Question 40

What is the final volume of nitrogen gas if the pressure of 5.8 L of the gas is decreased to one-half of its original pressure, and its absolute temperature is increased to double the original temperature?

A) 2.9 L
B) 5.8 L
C) 12 L
D) 23 L
E) 1.5 L

Question 41

Ammonia gas is synthesized according to the balanced equation below. N₂(g) + 3 H₂(g) → 2 NH₃(g)
If 1.55 L N₂ react with 4.92 L H₂, what is the theoretical yield (in liters) of NH₃? Assume that the volumes of reactants and products are measured at the same temperature and pressure.

A) 1.55 L
B) 3.10 L
C) 3.28 L
D) 4.93 L
E) 6.42 L

Question 42

Aqueous hydrochloric acid reacts with magnesium to produce hydrogen gas according to the balanced equation below. 2 HCl(aq) + Mg(s) → MgCl₂(aq) + H₂(g)
If 250.0 mL of 3.00 M HCl is combined with 9.92 g Mg, what volume of hydrogen gas can be produced? Assume the temperature and pressure of the gas are 25 °C and 0.988 atm, respectively. (R = 0.08206 L⋅atm/mol⋅K)

A) 4.60 L
B) 5.05 L
C) 9.28 L
D) 10.1 L
E) 18.6 L

Question 43

One way to isolate metals from their ores is by a chemical reaction of the metal oxide with carbon as shown below (M = metal):
$2 \mathrm { MO } ( s ) + \mathrm { C } ( s ) \rightarrow 2 \mathrm { M } ( s ) + \mathrm { CO } _ { 2 } ( g )$ If 31.75 g of a metal oxide reacts with excess carbon to form 4.07 L of CO₂ at 100°C and 1.50 atm, what is the identity of the metal?

A) Hg
B) Mg
C) Cu
D) Pb
E) Cd

Question 44

What volume of $\mathrm { H } _ { 2 } \mathrm { O } ( g )$ measured at STP is produced by the combustion of 6.50 g of natural gas $\left( \mathrm { CH } _ { 4 } \right)$ in excess oxygen? (R = 0.08206 L?atm/mol?K) $\mathrm { CH } _ { 4 } ( g ) + 2 \mathrm { O } _ { 2 } ( g ) \rightarrow \mathrm { CO } _ { 2 } + 2 \mathrm { H } _ { 2 } \mathrm { O } ( g )$

A) 4.54 L
B) 20 L
C) 9.08 L
D) 18.2 L
E) 3.25 L

Question 45

Into a 2.82-liter container at 25°C are placed 1.23 moles of O₂ gas and 3.20 moles of solid C (graphite). If the carbon and oxygen react completely to form CO(g), what will be the final pressure in the container at 25°C?

A) 21.3 atm
B) 11 atm
C) 1.79 atm
D) 27.7 atm
E) none of these

Question 46

A 22.4 L high pressure reaction vessel is charged with 0.5930 mol of iron powder and 1.65 atm of oxygen gas at standard temperature. On heating, the iron and oxygen react according to the balanced reaction below.
4Fe(s) + 3O₂(g) ? 2Fe₂O₃(s)
After the reaction vessel returns to standard temperature, and assuming the reaction goes to completion, what pressure of oxygen remains?

A) 1.20 atm
B) 1.65 atm
C) 0.858 atm
D) 0.445 atm
E) 0.00 atm

Question 47

The density of ethane, C₂H₆ (30.1 g/mol), at 27°C and 1.27 atm pressure is ___. (R = 0.08206 L⋅atm/mol⋅K)

A) 1.55 g/L
B) 18.6 g/L
C) 1.34 g/L
D) 0.644 g/L
E) 0.154 g/L

Question 48

Sodium azide decomposes rapidly to produce nitrogen gas. 2 NaN₃(s) → 2 Na(s) + 3 N₂(g)
What mass of sodium azide will inflate a 60.0 L airbag for a car to a pressure of 1.50 atm at 32 °C? (R = 0.08206 L⋅atm/mol⋅K)

A) 2.40 g
B) 67.2 g
C) 156 g
D) 234 g
E) 351 g

Question 49

The density of a gas is 1.25 g/L at STP. What is its molar mass?

A) 25.0 g/mol
B) 37.6 g/mol
C) 17.9 g/mol
D) 22.4 g/mol
E) 28.0 g/mol

Question 50

A mixture of KCl and KClO₃ weighing 1.65 grams was heated; the dry O₂ generated occupied 143 mL at STP. What percent by mass of the original mixture was KClO₃, which decomposes as follows:
$2 \mathrm { KClO } _ { 3 } ( s ) \rightarrow 2 \mathrm { KCl } ( s ) + 3 \mathrm { O } _ { 2 } ( g )$

A) 31.6%
B) 47.4%
C) 71.1%
D) 8.67%
E) 19.2%

Question 51

Consider the following reaction for the production of NO2. 2 NO(g) + O₂(g) → 2 NO₂(g)
What mass of O₂ is required to produce 5.00 L NO₂ at 305 K and 752 mm Hg? (R = 0.08206 L⋅atm/mol⋅K)

A) 0.198 g
B) 1.58 g
C) 3.16 g
D) 5.00 g
E) 6.33 g

Question 52

An unknown gaseous hydrocarbon contains 85.63% C. Its density is 1.524 g/L at 0.665 atm and 373 K. What is the molecular formula of the gas? (R = 0.08206 L⋅atm/mol⋅K)

A) C₂H₄
B) C₃H₆
C) C₄H₈
D) C₅H₁₀
E) C₆H₁₂

Question 53

What volume of O₂, measured at 24.0°C and 0.882 atm atm, will be produced by the decomposition of 3.00 g KClO₃? Assume 100% yield. (R = 0.08206 L?atm/mol?K) 2 KClO₃(s) ? 2 KCl(s) + 3 O₂(g)

A) $1.01 \times 10 ^ { 3 }$ mL
B) $6.76 \times 10 ^ { 2 }$ mL
C) $8.2 \times 10 ^ { 1 }$ mL
D) $4.51 \times 10 ^ { 2 }$ mL
E) none of these

Question 54

An excess of sodium hydroxide is treated with 2.3 L of dry hydrogen iodide gas measured at STP to produce sodium iodide and water. What is the mass of sodium iodide formed in the process?

A) 1.15 g
B) 30.8 g
C) 15.4 g
D) 19 g
E) 345 g

Question 55

When 0.5000 grams of an unknown hydrocarbon, C_xH_y, is completely combusted with excess oxygen, 1.037 L CO₂ gas and is produced at 98.3 °C and 1.000 atm. What is the empirical formula of the hydrocarbon? (R = 0.08206 L⋅atm/mol⋅K)

A) CH
B) CH₂
C) C₂H₃
D) C₃H₅
E) C₃H₈

Question 56

The density of H₂ gas in a rigid container is 0.117 g/L at 55 °C. What is the pressure of hydrogen in the flask if it is heated to 125 °C? (R = 0.08206 L⋅atm/mol⋅K)

A) 0.142 atm
B) 0.194 atm
C) 1.56 atm
D) 1.90 atm
E) 3.55 atm

Question 57

Under conditions of constant volume and moles of gas, at what temperature will 742 mm Hg of CH₄ gas have the same density as 742 mm Hg of O₂ gas at 273 K?

A) 137 K
B) 146 K
C) 191 K
D) 275 K
E) 545 K

Question 58

A 3.98 gram sample of a certain diatomic gas occupies a volume of 2.73-L at 1.00 atm and a temperature of 45°C. Identify this gas. (R = 0.08206 L⋅atm/mol⋅K)

A) H₂
B) F₂
C) Cl₂
D) N₂
E) O₂

Question 59

Which of the following samples contains the fewest moles of gas?

A) 1.00 L of CH₄ at STP
B) 1.00 L of Ar at STP
C) 1.00 L of NH₃ at STP
D) 1.00 L of H₂ at 0.0°C and 1.28 atm
E) 1.00 L of HCl at 20°C and 1.00 atm

Question 60

The following equation represents the partial combustion of methane, CH₄. 2CH₄(g) + 3O₂(g) → 2CO(g) + 4H₂O(g)
At constant temperature and pressure, what is the maximum volume of carbon monoxide that can be obtained from 3.86 × 10² L of methane and 1.93 × 10² L of oxygen?

A) 5.79 × 10² L
B) 3.86 × 10² L
C) 1.35 × 10³ L
D) 1.29 × 10² L
E) 7.72 × 10² L

Question 61

Calculate the root-mean-square velocity for the O₂ molecules in a sample of O₂ gas at 20.9°C. (R = 8.3145 J/K⋅mol)

A) 15.14 m/s
B) 127.6 m/s
C) 276.3 m/s
D) 478.6 m/s
E) 9.115 × 10²⁶ m/s

Question 62

Carbon monoxide reacts with oxygen to form carbon dioxide. 2 CO(g) + O₂(g) → 2 CO₂(g)
In a 1.00 L flask, 4.30 atm of CO reacts with 2.50 atm of O₂. Assuming that the temperature remains constant, what is the final pressure in the flask?

A) 1.80 atm
B) 2.50 atm
C) 4.30 atm
D) 4.65 atm
E) 6.80 atm

Question 63

A 10.0 L flask at 318 K contains a mixture of Ar and CH₄ with a total pressure of 1.040 atm. If the mole fraction of Ar is 0.715, what is the mass percent of Ar?

A) 13.8%
B) 68.8%
C) 71.5%
D) 82.9%
E) 86.2%

Question 64

Methane gas, CH₄, effuses through a barrier at a rate of 0.568 mL/minute. If an unknown gas effuses through the same barrier at a rate of 0.343 mL/minute, what is the molar mass of the gas?

A) 20.8 g/mol
B) 28.0 g/mol
C) 32.0 g/mol
D) 44.0 g/mol
E) 64.0 g/mol

Question 65

A gaseous mixture containing 1.5 mol Ar and 3.5 mol CO₂ has a total pressure of 8.4 atm. What is the partial pressure of CO₂?

A) 3 atm
B) 2 atm
C) 25 atm
D) 6 atm
E) 8 atm

Question 66

The rate of effusion of an unknown gas was measured and found to be 10.7 mL/min. Under identical conditions, the rate of effusion of pure oxygen (O₂) gas is 12.6 mL/min. Based on this information, the identity of the unknown gas could be:

A) N₂CH₂OF₂
B) CO₂N₂O
C) NO
D) C₂H₆
E) none of these

Question 67

Water can be decomposed by electrolysis into hydrogen gas and oxygen gas. What mass of water must decompose to fill a 3.00 L flask to a total pressure of 2.00 atm at 298 K with a mixture hydrogen and oxygen?
(R = 0.08206 L?atm/mol?K) 2 H₂O( $\ell$ ) ? 2 H₂(g) + O₂(g)

A) 1.47 g
B) 2.95 g
C) 4.42 g
D) 6.63 g
E) 8.84 g

Question 68

In which of the following reactions will the pressure increase upon completion of the reaction at constant temperature?

A) C(s) + O₂(g) → CO₂(g)
B) 2NO(g) + O₂(g) → 2NO₂(g)
C) C₂H₆O(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)
D) 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)
E) Cl₂(g) + 3F₂(g) → 2ClF₃(g)

Question 69

What is the total volume of gases produced at 819 K and 1.00 atm pressure when 256 g of ammonium nitrite undergoes the following decomposition reaction?
NH₄NO₂(s) ? N₂(g) + 2H₂O(g)

A) $6.72 \times 10 ^ { 1 }$ L
B) 22.4 L
C) $2.69 \times 10 ^ { 2 }$ L
D) $8.97 \times 10 ^ { 1 }$ L
E) $8.07 \times 10 ^ { 2 }$ L

Question 70

Real gases are those that

A) only behave ideally at high pressures or low temperatures
B) deviate from ideal behavior
C) are only available naturally in the earth's atmosphere
D) are called real gases because their behavior can easily be modeled
E) have an even number of protons

Question 71

At STP, as the molar mass of the molecules that make up a pure gas increases, the

A) root mean square speed of the molecules increases.
B) root mean square speed of the molecules decreases.
C) root mean square speed of the molecules remains constant.
D) root mean square speed increases to a maximum, then decreases.
E) none of the above.

Question 72

The partial pressures of CH₄, N₂, and O₂ in a sample of a gas mixture were found to be 191 mm Hg, 451 mm Hg, and 583 mm Hg, respectively. Calculate the mole fraction of nitrogen.

A) 1
B) 0..
C) 20.8
D) 0.
E) 0

Question 73

Real gases deviate from ideal behavior because of intermolecular forces and _____.

A) pressures within the chemical bonds
B) nonzero molecular volumes
C) ionization energies
D) molecular vibrations
E) a wide distribution of molecular speeds

Question 74

Non-ideal behavior for a gas is most likely to be observed under conditions of

A) high temperature and low pressure.
B) high temperature and high pressure.
C) low temperature and low pressure.
D) standard temperature and pressure.
E) low temperature and high pressure.

Question 75

A pressure of 1.00 atm has a metric equivalent of 1.01 × 10⁵ ________.

Question 76

Place the following gases in order of increasing average velocity at
300 K: Ar, CH₄, N₂, and N₂O.

A) Ar < CH₄ < N₂ < N₂O
B) N₂O < Ar < N₂ < CH₄
C) N₂O < N₂ < CH₄ < Ar
D) Ar < N₂ < N₂O < CH₄
E) CH₄ < N₂ < N₂O < Ar

Question 77

What is the volume occupied by a mixture of 0.329 mol of N₂ gas and 0.329 mol of O₂ gases at 0.83 atm and 23.2°C?

A) 5.79 × 10² L
B) 19.3 L
C) 0.755 L
D) 1.51 L
E) 9.65 L

Question 78

A vessel with a volume of 17.3 L contains 2.80 g of nitrogen gas, 0.403 g of hydrogen gas, and 79.9 g of argon gas. At 25°C, what is the pressure in the vessel?

A) 117 atm
B) 0 atm
C) 4 atm
D) 3 atm
E) 56 atm

Question 79

The molar mass of an unknown gas was measured by an effusion experiment. It was found that the unknown gas effused at a rate of 2.2 × 10⁻⁶ mol/hr, whereas the nitrogen gas effused at a rate of 3.1 × 10⁻⁶ mol/hr. The molar mass of the gas is _____.

A) 24 g/mol
B) 40 g/mol
C) 14 g/mol
D) 33 g/mol
E) 56 g/mol

Question 80

How long will it take 10.0 mL of Ne gas to effuse through a porous barrier if it has been observed that 125 minutes are required for 10.0 mL of Ar gas to effuse through the same barrier?

A) 1.41 min.
B) 31.9 min.
C) 63.1 min.
D) 88.8 min.
E) 176 min.