Deck 15: Gases and Kinetic Theory

Question 1

Why do vapor bubbles get larger in boiling water as they approach the surface?

A) They only appear to get larger, this being a magnification effect due to looking through the water.
B) The bubbles' pressure increases as they rise.
C) The pressure in the water decreases as the bubble moves toward the surface.
D) Bubbles always get bigger after they form.

Answer 1

The pressure in the water decreases as the bubble moves toward the surface.

Question 2

What thermodynamic quantity is held constant in Boyle's law?

A) pressure
B) volume
C) temperature
D) Both pressure and volume are each held constant.

Answer 2

temperature

Question 3

Avogadro's number is related to the universal gas constant R and the number of moles n by:

A) N_A = Rn
B) N_A = R/n
C) N_A = n/R
D) Avogadro's number cannot be related to these two quantities alone.

Answer 3

Avogadro's number cannot be related to these two quantities alone.

Question 4

A 4.00-L container holds half a mole of an ideal gas at a pressure of 18.5 atm. What is the gas temperature? (R = 0.0821 L · atm/mol · K)

A) 1800 K
B) 1190 K
C) 901 K
D) 450 K

Question 5

An ideal gas is confined to a container with adjustable volume. The number of moles and temperature are constant. By what factor will the volume change if pressure quadruples?

A) 16
B) 4
C) 1/4
D) 1/16

Question 6

With molar quantity and temperature held constant, by what factor does the pressure of an ideal gas change when the volume is four times bigger?

A) 16
B) 4
C) 1/4
D) 1/16

Question 7

For a quantity of ideal gas, which of the following is constant?

A) PTV
B) P/TV
C) PT/V
D) PV/T

Question 8

In the relationship $\Delta$ P $\Delta$ T , what scale is used for temperature?

A) Fahrenheit
B) Celsius
C) Kelvin
D) Both Celsius and Kelvin may be used since the degree size is the same for both.

Question 9

The gas, , is used in outside grills, and several moles of this gas will burn during an afternoon's grilling. What is the mass of one molecule of this gas?

A) g
B) kg
C) kg
D) kg

Question 10

An ideal gas is confined to a container with constant volume. The number of moles is constant. By what factor will the pressure change if the absolute temperature triples?

A) 2/3
B) 1/3
C) 3
D) 9

Question 11

With volume and molar quantity held constant, by what factor does the absolute temperature change for an ideal gas when the pressure is three times bigger?

A) 0.3
B) 3.0
C) 5.0
D) 25.0

Question 12

The pressure in a constant-volume gas thermometer extrapolates to zero at what temperature?

A) 0 $\degree$ C
B) 0 K
C) 0 $\degree$ F
D) 0 Pa

Question 13

Four moles of nitrogen gas are contained in an enclosed cylinder with a movable piston. If the gas temperature is 298 K, and the pressure is 1.01 *10⁶ N/m², what is the volume? (R = 8.31 J/mol·K)

A) 9.81 *10^-3 m³
B) 4.90 *10^-3 m³
C) 17.3 *10^-3 m³
D) 8.31 *10^-3 m³

Question 14

An ideal gas is confined to a container with adjustable volume. The pressure and mole number are constant. By what factor will volume change if absolute temperature doubles?

A) 4.0
B) 2.0
C) 1/2
D) 1/4

Question 15

The value 1.38 *10^-23 J/K is known as:

A) the universal gas constant.
B) Boltzmann's constant.
C) Avogadro's number.
D) the molar specific.

Question 16

Which law is for a quantity of gas held at constant volume?

A) Boyle's law
B) Charles's law
C) Gay-Lussac's law
D) Avogadro's law

Question 17

Four moles of nitrogen gas are contained in an enclosed cylinder with a movable piston. If the molecular mass of nitrogen is 28 u, how many grams of nitrogen are present?

A) 0.14
B) 56
C) 42
D) 112

Question 18

What is the mass of 2 moles of carbon dioxide?

A) 88 g
B) 80 g
C) 64 g
D) 56 g

Question 19

How many molecules are there in 14 grams of nitrogen gas?

A) N_A/2
B) N_A
C) 2 N_A
D) The answer is not given.

Question 20

What is the mass of a mole of oxygen gas?

A) 8 g
B) 16 g
C) 24 g
D) 32 g

Question 21

Suppose there are 2 moles of a gas in a container of fixed size and the average spacing of molecules in the container is 4.0 nm. If an additional 14 moles of the gas are added to the container and thermal equilibrium is established, what is the new average spacing of the molecules?

A) 2.0 nm
B) 0.50 nm
C) 1.4 nm
D) 2.8 nm

Question 22

One way to heat a gas is to compress it. A gas at 1.00 atm at 25.0 $\degree$ C is compressed to one tenth of its original volume, and it reaches 30.0 atm pressure. What is its new temperature?

A) 1500 K
B) 621 $\degree$ C
C) 1192 $\degree$ C
D) 919 $\degree$ C

Question 23

The volume holding 0.63 mole of an ideal gas is compressed to 1/4 of its original volume by a piston. At the same time the pressure of the gas triples. If the original absolute temperature of the gas was T, that is the new temperature after compression?

A) 4/3T
B) 3/4T
C) 0.63(3/4T)
D) 0.63(4/3T)

Question 24

The sulfur hexafluoride molecule consists of one sulfur atom and six fluorine atoms. The atomic masses of sulfur and fluorine are 32.0 u and 19.0 u, respectively. One-half mole of this very heavy gas has what mass?

A) 32 g
B) 73 g
C) 146 g
D) 608 g

Question 25

A spherical air bubble originating from a scuba diver at a depth of 30.0 m has a diameter of 1.0 cm. What will the bubble's diameter be when it reaches the surface? (Assume constant temperature.)

A) 0.7 cm
B) 1.0 cm
C) 1.4 cm
D) 1.6 cm

Question 26

Boltzmann's constant, k_B, may be derived as a function of R, the universal gas constant, and N_A, Avogadro's number. Which expresses the value of k_B?

A) N_AR²
B) N_AR
C) R/N_A
D) N_A/R

Question 27

Tricia puts 66 g of dry ice (solid CO₂) into a 2.0-L container and seals the top. The dry ice turns to gas at room temperature (20 $\degree$ C). Find the pressure increase in the 2.0-L container. (One mole of CO₂ has a mass of 44 g and R = 0.0821 L·atm/mol·K. Ignore the initial volume of the dry ice.)

A) 6.0 atm
B) 12 atm
C) 18 atm
D) 2.0 atm

Question 28

A helium-filled weather balloon has a 0.90-m radius at liftoff where air pressure is 1.0 atm and the temperature is 298 K. When airborne, the temperature is 210 K, and its radius expands to 3.5 m. What is the pressure at the airborne location?

A) 0.50 atm
B) 0.012 atm
C) 0.019 atm
D) 0.38 atm

Question 29

Estimate the volume of a helium-filled balloon if it is to lift a payload of 1000 kg. The density of air is 1.29 kg/m³ and helium has a density of 0.178 kg/m³.

A) 4410 m³
B) 900 m³
C) 450 m³
D) 225 m³

Question 30

The mass of a hot-air balloon and its cargo (not including the air inside) is 250 kg. The air outside is at a temperature of 10 $\degree$ C and a pressure of 1 atm = 10⁵ N/m². The volume of the balloon is 400 m³. Which temperature below of the air in the balloon will allow the balloon to just lift off? (Air density at 10 $\degree$ C is 1.25 kg/m³.)

A) 37 $\degree$ C
B) 293 $\degree$ C
C) 99 $\degree$ C
D) 200 $\degree$ C

Question 31

If the temperature of a volume of ideal gas increases for 100°C to 200°C, what happens to the average kinetic energy of the molecules?

A) It halves.
B) It doubles.
C) It increases but less that double.
D) It increases more than double.

Question 32

The ideal gas law treats gas as consisting of:

A) atoms.
B) molecules.
C) chemicals.
D) bubbles.

Question 33

Two moles of an ideal gas at 3.0 atm and 10 $\degree$ C are heated up to 100 $\degree$ C. If the volume is held constant during this heating, what is the final pressure?

A) 4.5 atm
B) 4.0 atm
C) 0.14 atm
D) 1.0 atm

Question 34

One mole of an ideal gas at 1.00 atm and 0.00 $\degree$ C occupies 22.4 L. How many molecules of an ideal gas are in one cm³ under these conditions?

A) 28.9
B) 22,400
C) 2.69 *10¹⁹
D) 6.02 * 10²³

Question 35

A pressure of 2.0 *10 ^{- 7} mm of Hg is achieved in a vacuum system. How many gas molecules are present per liter volume if the temperature is 293 K? (760 mm of Hg = 1 atm, R = 0.0821 L · atm/mol · K, and N_A = 6.02 *10²³)

A) 16 * 10¹⁸
B) 6.6 * 10¹²
C) 3.3 *10¹²
D) 3.4 *10⁹

Question 36

How many moles of air must escape from a 10 m * 8.0 m *5.0 m room when the temperature is raised from 0 $\degree$ C to 10 $\degree$ C? Assume the pressure remains unchanged at one atmosphere while the room is heated.

A) 1.3 *10³ moles
B) 1.2 * 10³ moles
C) 6.5 *10² moles
D) 3.7 * 10² moles

Question 37

How many atoms are present in a sample of pure iron with a mass of 210 g? (The atomic mass of iron = 56 u and N_A = 6.02* 10²³.)

A) 1.8 *10¹⁹
B) 2.3 *10²⁸
C) 2.3 *10²⁴
D) 3.2 * 10²⁸

Question 38

A tank with a volume of 0.200 m³ contains 27.0 $\degree$ C helium gas at a pressure of 63.5 atm. How many balloons can be blown up if each filled balloon is a sphere 30.0 cm in diameter at 27.0 $\degree$ C and absolute pressure of 1.20 atm? Assume all the helium is transferred to the balloons.

A) 1180 balloons
B) 884 balloons
C) 749 balloons
D) 375 balloons

Question 39

The average kinetic energy of a molecule in a monatomic ideal gas is given by:

A)
B)
C)
D) none of the these.

Question 40

A storeroom has a volume of 30 m³ and is filled with air of an average molecular mass of 29 u. What is the mass of the air in the room at a pressure of 1.0 atm and temperature of 22 $\degree$ C? R = 0.082 L · atm/mol · K

A) 36 kg
B) 1240 kg
C) 72 kg
D) 700 kg

Question 41

The specific heat at constant volume per mole of is for what type of molecule?

A) monatomic
B) diatomic
C) polyatomic
D) any type

Question 42

What is the internal energy of 42 moles of Neon gas (molecular mass = 20 u) at 27 $\degree$ C? (R = 8.31 J/mol ·K)

A) 1.9 *0 10⁵ J
B) 1.6 *10⁵ J
C) 3.8 * 10³ J
D) It depends on the container size, which is not given.

Question 43

What is (are) the unit(s) for the diffusion constant?

A) m²
B) m²/s
C) It is unitless.
D) m/s^1/2

Question 44

Consider two containers with the same volume and temperature. Container One holds "dry" air (a mixture of nitrogen and oxygen). Container Two holds "moist" air. The "moist" air has the same ratio of nitrogen to oxygen molecules but also contains water vapor. According to the ideal gas law, if the pressures are equal, the weight of the gas in Container One will be:

A) lighter than the gas inside the second container.
B) equal to the weight of the gas in the second container.
C) heavier than the gas inside the second container.
D) all the above are incorrect because the pressures cannot be equal.

Question 45

A quantity of a monatomic ideal gas expands to four times the volume while maintaining the same pressure. If the internal energy of the gas were U₀ before the expansion, what is it after the expansion?

A) U₀
B) 2U₀
C) 4U₀
D) The change in temperature must also be known to answer this question.

Question 46

Suppose the pressure of 20 g of an ideal monatomic gas is tripled while its volume is halved. What happens to the internal energy of the gas?

A) It stays the same, as the described changes do not involve internal energy.
B) It increases.
C) It decreases 33%.
D) This depends on the molecular weight of the gas involved, thus this is indeterminate.

Question 47

When a sealed container of ideal gas has its temperature increase from 250 K to 500 K, what happens to the mean free path of the molecules?

A) It decreases to half of its original value.
B) It stays the same.
C) It increases by the factor .
D) It quadruples.

Question 48

For a monatomic gas, is

A) the specific heat per mole at constant volume.
B) the specific heat per unit mass at constant volume.
C) .
D) none of the above.

Question 49

John rapidly pulls a plunger out of a cylinder, increasing its volume. As the plunger moves away, the gas molecules bouncing elastically off the plunger are:

A) rebounding at a higher speed than they would have if the plunger weren't removed.
B) rebounding at a lower speed than they would have if the plunger weren't removed.
C) rebounding at the same speed as they would have if the plunger weren't removed.
D) Whether they speed up or slow down depends on how fast the plunger is removed.

Question 50

In a system of ideal gas with P, V, and T constant, if the molecules diffuse an average displacement of 2 cm in 4 s, on the average what would the average displacement be for a time of 200 s?

A) 5 cm
B) 10 cm
C) 10 cm
D) more than 10 cm

Question 51

The temperature of a quantity of ideal gas in a sealed container is increased from 0°C to 819°C. What happens to the speed of the molecules with average kinetic energy of the gas as a result of this temperature increase?

A) It does not change since this speed is independent of temperature.
B) It increases but it is less than double the original speed.
C) It doubles.
D) It quadruples.

Question 52

If the temperature of a gas doubles, by what factor does the speed of a molecule with the average kinetic energy change?

A) It increases by a factor of 2.
B) It increases by a factor of .
C) It increases by a factor of .
D) It increases by a factor of 4.

Question 53

What is the internal energy of a monatomic ideal gas with pressure 6 *10⁵ Pa and with volume 2 m³?

A) 6 *10⁵ J
B) 18 * 10⁵ J
C) 9 * 10⁵ J
D) More information is needed to find this value.

Question 54

If the average kinetic energy of the molecules of a monatomic ideal gas at 30°C is doubled, what is the resulting temperature of the gas?

A) It becomes $\degree$ C.
B) It becomes 606°C.
C) It becomes 60°C.
D) It becomes 333°C.

Question 55

For an ideal gas of a given mass, if the pressure remains the same and the volume decreases:

A) the average kinetic energy of the molecules decreases.
B) the average kinetic energy of the molecules stays the same.
C) the average kinetic energy of the molecules increases.
D) Nothing can be determined about the molecular kinetic energy.

Question 56

The internal energy of a monatomic ideal gas is equal to which of the following?

A) (3/2)PV
B) (3/2)nT/V
C) 3T/P
D) none of these

Question 57

The noble gases, listed by increasing molecular weight, are He, Ne, Ar, Kr, Xe, and Rn. If samples of 1 mole each of these gases are placed in separate containers and heated to 300 K, which gas has the greatest internal energy and the molecules of which gas have the lowest average speed?

A) The He has the greatest internal energy, and Rn has the lowest speed.
B) The Rn has the greatest internal energy, and He has the lowest speed.
C) All the gases have the same internal energy, and Rn has the lowest speed.
D) All the gases have the same internal energy, and He has the lowest speed.

Question 58

If the temperature of an ideal gas contained in a box is increased:

A) the average velocity of the molecules in the box will be increased.
B) the average speed of the molecules in the box will be increased.
C) the distance between molecules in the box will be increased.
D) all of the above.

Question 59

If an average molecule diffuses to a displacement of 4 cm in 5 s, how long would it take for such a molecule to diffuse to a displacement of 16 cm?

A) 10 s
B) 20 s
C) 36 s
D) 80 s

Question 60

The absolute temperature of a monatomic ideal gas is directly proportional to which of the following properties, when taken as an average, of the molecules of that gas?

A) speed
B) momentum
C) mass
D) kinetic energy

Question 61

Suppose an average molecule's displacement is 1.2 m in one hour. What is the diffusion constant in SI units (m, kg, s).

A) 4.0 *10 ^{- 4} SI units
B) 1.0 *10 ^{- 4} SI units
C) 2.8 *10 ^{- 5} SI units
D) 4.6 *10 ^{- 8} SI units

Question 62

The ideal gas in a sealed container has its absolute temperature quadrupled. What happens to the average time between molecular collisions in the gas?

A) It stays the same.
B) It decreases to half its original value.
C) It decreases but not to half its original value.
D) It increases.

Question 63

In the uranium isotope separation for and , the gas molecules used are , uranium hexafluoride. The key to the separation is that in thermal equilibrium the average speed of the molecule is different from that of the molecule. The fluorine atoms involved are all . Which of the hexafluoride molecules has the higher average speed and what is the ratio of the faster speed to the slower speed?

A) The is the faster one. The ratio of its speed to that of is 1.009.
B) The is the faster one. The ratio of its speed to that of is 1.004.
C) The is the faster one. The ratio of its speed to that of is 1.009.
D) The is the faster one. The ratio of its speed to that of is 1.004.