Deck 5: Changes of State and the Gas Laws

Question 1

What happens to the speed of molecules when the molecules are frozen?

A) The speed stays the same.
B) The molecules speed up.
C) The molecules slow down.
D) The speed does not change in a predictable way.
E) The molecules stop moving completely.

Answer 1

The molecules slow down.

Question 2

One of the symptoms of the bends is joint pain. Why does joint pain occur with the bends?

A) Nitrogen bubbles expand in the joints as pressure decreases.
B) The bends causes muscle spasms, which leads to joint pain.
C) The bends causes a loss of cartilage in joints.
D) Lactic acid is released as a stress response.
E) The reason for joint pain is unknown.

Answer 2

Nitrogen bubbles expand in the joints as pressure decreases.

Question 3

Which of the following physical change is the result of a decrease in temperature?

A) vaporization
B) sublimation
C) melting
D) freezing
E) All of the above

Answer 3

freezing

Question 4

Which of the following is the common treatment for the bends?

A) No treatment exists.
B) A pressure decrease to a fraction of atmospheric pressure.
C) Treatment with nitrogen binding drugs.
D) A blood transfusion.
E) Slow depressurization in a hyperbaric chamber.

Question 5

Why must a SCUBA diver ascend slowly from a dive?

A) to conserve air
B) to avoid the formation of nitrogen bubbles in the bloodstream
C) to avoid breathlessness
D) to allow time to change air tanks
E) There is no reason to ascend slowly from a dive.

Question 6

You boil a pot of water (H₂O) to make spaghetti and, when the water reaches its boiling point, you notice that it bubbles. What are these bubbles composed of?

A) nothing
B) H₂
C) O₂
D) H₂ and O₂
E) H₂O

Question 7

What type of change in pressure causes the bends and why?

A) an increase in pressure, because it results in nitrogen rapidly diffusing out of the bloodstream
B) an increase in pressure, because it results in nitrogen rapidly dissolving into the bloodstream
C) a decrease in pressure, because it results in nitrogen rapidly diffusing out of the bloodstream
D) a decrease in pressure, because it results in nitrogen slowly dissolving into the bloodstream
E) The bends is not a result of pressure changes.

Question 8

In which of the following phase changes is energy transferred to a substance?

A) freezing water in the freezer
B) water condensing on the outside of a glass
C) boiling water to make steam
D) the deposition of a cloud to make snow
E) All of the above

Question 9

Which process requires more energy per gram: melting ice or boiling water?

A) They both require the same amount of energy because both processes involve breaking intermolecular forces.
B) Melting ice takes more energy because more intermolecular forces are broken.
C) Boiling water takes more energy because more intermolecular forces are broken.
D) Melting ice takes more energy because it occurs at 0 $\degree$ C instead of 100 $\degree$ C.
E) The energy of these processes has never been compared.

Question 10

Which statement best describes how heat energy is involved in changing water into steam?

A) Heat energy breaks the intermolecular forces holding molecules of water together.
B) Heat energy is released from intermolecular forces as the molecules of water break apart.
C) Heat energy breaks the covalent bonds holding molecules of water together.
D) Heat energy is released from covalent bonds as the molecules of water break apart.
E) Heat energy is not involved in this change.

Question 11

Why is water (H₂O) a liquid at room temperature while methane (CH₄) is a gas?

A) Water forms hydrogen bonds and methane only forms dispersion forces.
B) Water forms dispersion forces and methane forms hydrogen bonds.
C) Water has a higher molecular weight than methane.
D) Methane has a higher molecular weight than water.
E) Methane has more atoms than water.

Question 12

How do phase changes differ from chemical reactions?

A) There is no difference between them.
B) Phase changes occur more rapidly than chemical reactions.
C) Only chemical reactions involve changes in energy.
D) Only chemical reactions follow the conservation of matter.
E) Phase changes do not involve breaking or making covalent bonds.

Question 13

When heat energy is added to a solid and liquid mix at the melting point, the temperature does not increase, as illustrated by horizontal line C. Which of the statements below best describes what happens to the heat energy added to the solid and liquid?

A) It increases the kinetic energy of the molecules.
B) It decreases the kinetic energy of the molecules.
C) It breaks the intermolecular forces between the molecules.
D) It makes new intermolecular forces between molecules.
E) It just passes through the solid and liquid, which is why the temperature does not increase.

Question 14

Which of the following changes of state is correctly named?

A) dry ice becoming a gas - melting
B) water on a hot sidewalk in summer changing to steam - vaporization
C) a friend's perfume producing an aroma that fills the room - evaporation
D) breath fogging a windshield on a cold day - deposition
E) making ice cream from milk in an ice cream maker - sublimation

Question 15

Formaldehyde, a common preservative, is shown in the illustration below. If liquid formaldehyde is boiled, which of the following choices best depicts how formaldehyde looks in the resulting vapor?

A)a
B)b
C)c
D)d
E)e

Question 16

A liquid has temperature A as shown on the heating curve. What will happen to the temperature of the liquid if heat is added to it?

A) The temperature will stay the same.
B) The temperature will decrease.
C) The temperature will increase and then decrease.
D) The temperature will increase.
E) It is not possible to determine what will happen to the temperature of the liquid by looking at the chart.

Question 17

How are vaporization and evaporation similar?

A) Both occur only at high temperatures.
B) Both occur only at very low temperatures.
C) Both are the transformation of liquid into a gas.
D) Both always involve water.
E) Vaporization and evaporation mean exactly the same thing.

Question 18

What change of phase is represented by B on the heating curve?

A) boiling
B) freezing
C) sublimating
D) melting
E) It is not possible to determine what will happen to the temperature of the liquid by looking at the chart.

Question 19

Which statement best describes why steam burns are more severe than boiling water burns?

A) Steam transfers more heat energy to the skin than boiling water due to the change of state from gas to liquid.
B) Steam remains hot in the air while water cools quickly as it pours.
C) Steam is hotter than boiling water.
D) Steam covers the skin more thoroughly than water.
E) Actually, steam does not cause more severe burns than boiling water.

Question 20

Which of the following changes is not correctly labeled as a chemical reaction or a change of state?

A) rust forming on metal, a chemical reaction.
B) steam coming off of a cup of coffee, a change of state.
C) an ice cube melting in a drink, a change of state
D) the combustion of gasoline to give carbon dioxide and water, a chemical reaction
E) bubbles forming in a just opened can of soda, a chemical reaction

Question 21

What is the electron geometry of the carbon indicated by the arrow in this molecule of acetone?

A) linear
B) bent
C) trigonal planar
D) trigonal pyramidal
E) tetrahedral

Question 22

Which arrow best shows the molecular dipole of acetone?

A)a
B)b
C)c
D)d
E)e

Question 23

Which statement best describes how heat is involved in the change in the diagram below?

A) Heat energy breaks the intermolecular forces holding molecules of water together.
B) Heat energy is released from intermolecular forces as the molecules of water break apart.
C) Heat energy breaks the covalent bonds holding molecules of water together.
D) Heat energy is released from covalent bonds as the molecules of water break apart.
E) Heat energy is not involved in this change.

Question 24

Arrow A points to

A) a polar covalent bond.
B) a nonpolar bond.
C) a dispersion force.
D) heat.
E) a hydrogen bond.

Question 25

To accomplish the change of phase shown in the diagram below, you could

A) drink a glass of water.
B) put water in the freezer.
C) boil water.
D) leave a glass of water on the kitchen counter.
E) let an ice cube melt in the sink.

Question 26

Does isopropyl alcohol have a higher or lower boiling point than acetone?

A) higher, because isopropyl alcohol can hydrogen bond
B) lower, because isopropyl alcohol can hydrogen bond
C) higher, because isopropyl alcohol can form dispersion forces
D) lower, because isopropyl alcohol can form dispersion forces
E) It is not possible to determine the answer based on the information provided.

Question 27

What occurs over the course of this physical change illustrated below?

A) Hydrogen bonds are broken.
B) Hydrogen bonds are formed.
C) Polar covalent bonds are broken.
D) Polar covalent bonds are formed.
E) Both hydrogen bonds and polar covalent bonds are broken.

Question 28

Which bond in acetone, shown below, is correctly labeled with a dipole arrow?

A)a
B)b
C)c
D)d
E)e

Question 29

What is the molecular geometry of the carbon indicated by the arrow in this molecule of acetone?

A) linear
B) bent
C) trigonal planar
D) trigonal pyramidal
E) tetrahedral

Question 30

Which of the following types of molecules would you expect to have the highest vapor pressure at a given temperature?

A) nonpolar molecules, because there are few intermolecular forces holding them together
B) nonpolar molecules, because there are many intermolecular forces holding them together
C) polar molecules, because there are some intermolecular forces holding them together
D) ionic compounds, because there are many intermolecular forces holding them together
E) ionic compounds, because there are few intermolecular forces holding them together

Question 31

Which of the molecules in this table is the most volatile?

A) acetone
B) methanol
C) formic acid
D) chloroform
E) pentane

Question 32

What happens to acetone when it is boiled?

A) More intermolecular forces are formed.
B) The nonpolar covalent bonds are broken.
C) The polar covalent bonds are broken.
D) All bonds in the molecule are broken.
E) The intermolecular forces are broken.

Question 33

This diagram shows

A) the decomposition of water.
B) the combustion of water.
C) ice changing to water (melting).
D) water changing to gas (boiling).
E) gas changing to liquid (condensation).

Question 34

Acetone, shown here, is a common solvent and component of fingernail polish remover. Which of the following Lewis structures is acetone?

A)a
B)b
C)c
D)d
E)e

Question 35

Which molecule in this table has the highest boiling point?

A) acetone
B) methanol
C) formic acid
D) chloroform
E) pentane

Question 36

Are any bonds in acetone, shown below, polar?

A) No, none are polar.
B) Yes, the C-C bonds are polar.
C) Yes, the C=O bond are polar.
D) Yes, the C-H bonds are polar.
E) Yes, all bonds in acetone are polar.

Question 37

Which of the following statements best describes vapor pressure?

A) Vapor pressure is the pressure of a gas at room temperature.
B) Vapor pressure is the pressure of a liquid at room temperature.
C) Vapor pressure is a measure of the strength of a substance's odor.
D) Vapor pressure is a measure of a material's boiling point.
E) Vapor pressure is the pressure of the vapor above a liquid or solid.

Question 38

Which atom has the highest electronegativity in this molecule of acetone?

A) carbon
B) oxygen
C) hydrogen
D) carbon and hydrogen
E) They all have the same electronegativity.

Question 39

Arrow B points to

A) a polar covalent bond.
B) a nonpolar bond.
C) a dispersion force.
D) heat.
E) a hydrogen bond.

Question 40

What is the strongest intermolecular that exists between molecules of acetone in the liquid or solid state?

A) dispersion forces
B) dipole-dipole forces
C) hydrogen bonds
D) ionic interactions
E) None of the above

Question 41

Which of the following properties is not a property of gases?

A) Gas particles move in constant random motion.
B) The higher the temperature of a gas, the greater its kinetic energy.
C) Gases are compressible.
D) Dispersion forces are the only type of attractive forces found in gases.
E) A sample of a gas is mostly empty space.

Question 42

Which of the following statements about the relationship between pressure and temperature is true?

A) As temperature increases, the volume of a gas decreases.
B) The volume of a gas is unaffected by temperature changes.
C) The volume of a gas is affected by temperature changes, but it is not possible to predict how it is affected.
D) Increasing the temperature would make some of the gas escape from the balloon, decreasing the volume.
E) As temperature increases, the volume of a gas also increases.

Question 43

Balloon A is placed into a container that has a higher pressure than atmospheric pressure. Which balloon would you predict to be the new size of balloon A?

A) balloon B
B) balloon C
C) balloon D
D) either balloon B or D
E) either balloon B or C

Question 44

Atmospheric pressure at sea level is ________. At elevations higher than sea level, atmospheric pressure is_________.

A) less than 1 atm; 1 atm
B) 1 atm; less than 1 atm
C) greater than 1 atm; 1 atm
D) 1 atm; greater than 1 atm
E) 1 atm; impossible to predict

Question 45

The atmospheric pressure in Denver is 0.85 atm. What is the atmospheric pressure in torr?

A) 0.0011 torr
B) 890 torr
C) 650 torr
D) 12 torr
E) 0.058 torr

Question 46

Which of the following instruments is used to measure atmospheric pressure?

A) a barometer
B) a hydrometer
C) a sphygmomanometer
D) a manometer
E) an atmospherometer

Question 47

On a cool morning (12 $\degree$ C), a balloon is filled with 1.5 L of helium. By mid-afternoon, the temperature has soared to 32 $\degree$ C. What is the new volume of the balloon?

A) 720 L
B) 11.3 L
C) 1.6 L
D) 1.4 L
E) 0.20 L

Question 48

Which statement best describes why it is important to know the vapor pressure of a material before working with it?

A) It is not important because the risk of inhalation increases for materials with low vapor pressure.
B) It is not important because the risk of inhalation increases for materials with high vapor pressure.
C) It is not important because the toxicity increases for materials with low vapor pressure.
D) It is not important because the toxicity increases for materials with high vapor pressure.
E) It is not important to know the vapor pressure of materials.

Question 49

A nitrogen bubble with a volume of 0.0050 mL forms in the joint of a scuba diver as she ascends rapidly from a pressure of 4.1 atm to the surface, with a pressure of 1.0 atm. What is the volume of the bubble at the surface?

A) 820 mL
B) 4.1 mL
C) 0.0012 mL
D) 0.021 mL
E) 0.0050 mL

Question 50

This diagram shows balloons of various sizes filled with helium gas. Balloon A is at STP. If you heat balloon A, which balloon would you predict would best represent the new size of balloon A?

A) balloon B
B) balloon C
C) balloon D
D) either balloon B or D
E) either balloon C or D

Question 51

Which of the following circumstances does NOT cause decompression sickness?

A) a deep-sea diver suddenly ascending
B) flying in an airplane shortly after diving
C) hiking in the mountains
D) a miner coming out of a pressurized mine
E) cabin pressure in an airplane failing

Question 52

What is the relationship between polarity and vapor pressure?

A) These two properties are unrelated.
B) The more polar the molecule, the higher the vapor pressure.
C) The less polar the molecule, the higher the vapor pressure.
D) Nonpolar molecules have lower vapor pressures.
E) The relationship changes depending upon the temperature.

Question 53

It is important to check tire pressure periodically, especially when the outside temperature drops. You can see why this is so by calculating the tire volume after a large drop in temperature as follows: A well-inflated tire holds about 11 L of air at 298 K (25 $\degree$ C). If the temperature drops to 273 K (0 $\degree$ C), what is the new volume of the air in the tire?

A) It is not possible to determine because the temperature has dropped to 0 $\degree$ C.
B) 0 L
C) 10. L
D) 12 L
E) 7300 L

Question 54

In which of the following statements is the gas variable correctly described?

A) Temperature is a measure of the space occupied by a gas.
B) Volume increases as the collisions of gas particles with the walls of the container increases.
C) Temperature is related to the average speed of gas particles.
D) The number of moles of a gas decreases as the volume of the gas increases.
E) When gas particles move faster, the pressure of the gas must increase.

Question 55

According to Avogadro's Law, What is the meaning of this law?

A) Adding moles of gas decreases the volume of the gas.
B) Adding moles of gas increases the volume of the gas.
C) The volume is inversely proportional to the moles of air.
D) Gas particles shrink when they are crowded.
E) Gas particles expand when they are crowded.

Question 56

A scuba diver dives down to 15 m, where the pressure is 2.5 atm. The scuba diver then inhales 500. mL of air and holds his breath while ascending to the water surface, where the pressure is 1 atm. What is the volume of the air in the diver's lungs at the surface? Assume that T and n are constant.

A) 0.0050 mL
B) 0.20 mL
C) 5.0 mL
D) 200 mL
E) 1250 mL

Question 57

Which of the following statements best describes the process that occurs when air is inhaled into the lungs?

A) The diaphragm moves up, the lungs expand, pressure decreases, and air is inhaled.
B) The diaphragm moves down, the lungs expand, pressure decreases, and air is inhaled.
C) The diaphragm moves up, the lungs contract, pressure increases, and air is inhaled.
D) The diaphragm moves down, the lungs expand, pressure increases, and air is inhaled.
E) The diaphragm moves down, the lungs contract, pressure decreases, and air is inhaled.

Question 58

You are riding your bike and run over a thorn, puncturing your tire. The air in the tire is released, resulting in a flat. What is the relationship between the volume (V_i) and moles of air (n_i) in the inflated tire and the volume (V_f) and moles of air in the flat tire (n_f)?

A)
B)
C)
D)
E) There is no relationship between the moles of air and the volume of air in the tire.

Question 59

Which of the following statements best describes pressure?

A) Pressure is heat energy applied to a given volume.
B) Pressure is heat energy applied to a given area.
C) Pressure is force applied to a given volume.
D) Pressure is force applied to a given area.
E) Pressure is heat energy or force applied to a substance.

Question 60

A narrow tube on a road bike should be inflated to about 100 psi. What is this pressure in atmospheres?

A) 0.1 atm
B) 0.5 atm
C) 7 atm
D) 1000 atm
E) 2 * 10⁵ atm

Question 61

How does the pressure of a gas change when it is heated in a sealed container with a constant volume (note: it is not a good idea to do this without special equipment)?

A) It will not change because there is no relationship between temperature and pressure.
B) It will increase because P₁T₁=P₂T₂.
C) It will decrease because P₁T₁=P₂T₂.
D) It will increase because P₁/T₁ = P₂/T₂.
E) It will decrease because P₁/T₁ = P₂/T₂.

Question 62

The total pressure in a mixture of gases is equal to the partial pressure(s) of

A) the gas present in the greatest quantity.
B) all of the gases added together.
C) the gas with the greatest volatility.
D) the gas that is most important.
E) the gas with the greatest partial pressure.

Question 63

How does the pressure of a gas change when it is compressed?

A) It will not change because there is no relationship between volume and pressure.
B) It will increase because P₁V₁ = P₂V₂.
C) It will decrease because P₁V₁ = P₂V₂.
D) It will increase because P₁/V₁ = P₂/V_2.
E) It will decrease because P₁/V₁ = P₂/V_2.

Question 64

Which has a higher partial pressure of oxygen: inhaled air or exhaled air?

A) inhaled air, because our lungs absorb some of the oxygen in the air
B) exhaled air, because our lungs absorb some of the oxygen in the air
C) inhaled air, because oxygen is removed from the body by breathing
D) exhaled air, because oxygen is removed from the body by breathing
E) The partial pressures in inhaled and exhaled air are equal because air always contains the same concentration of oxygen.

Question 65

Air is primarily composed of nitrogen (594 torr) and oxygen (160 torr). There is also carbon dioxide and water vapor in the air. Assuming that atmospheric pressure is 760 torr, what is the partial pressure of carbon dioxide and water vapor combined?

A) 1514 torr
B) 754 torr
C) 500 torr
D) 166 torr
E) 6 torr

Question 66

Two sealed boxes are filled with gas. The first box contains more molecules moving faster and therefore a higher pressure. The second box contains fewer molecules moving slower and therefore a lower pressure. Why does the first box have a higher pressure?

A) The more molecules, the higher the pressure.
B) The more collisions against the side of the box, the higher the pressure.
C) The fewer molecules, the higher the pressure.
D) When there is high pressure, it is harder for molecules to move, so theycreate heat and pressure.
E) There is no reason for the first box to have high pressure.

Question 67

You have a balloon containing 1.4 L of gas in it at standard temperature and pressure. Which conversion factor would you use to convert this number to moles?

A) 1 mole/22.4 L
B) 1 L/22.4 mole
C) 22.4 L/1 mole
D) 6.02 x 10²³ L/1 mole
E) 1 L/6.02 x 10²³ mole

Question 68

The temperature of a gas at 1.00 atm and 8.00 $\degree$ C is increased to 20.0 $\degree$ C, resulting in a change of pressure. Which equation would you use to calculate the new pressure?

A) P₁V₁ = P₂V₂
B) P₁/V₁ = P₂/V₂
C) P₁T₁=P₂T₂
D) P₁/T₁ = P₂/T₂
E) V₁/n₂ =V₂/n₂

Question 69

A sample of gaseous neon has a volume of 68.2 L at STP. How many moles of neon are in the sample?

A) 0.328 moles
B) 3.04 moles
C) 68.2 moles
D) 1530 moles
E) 4.11 * 10²⁵ moles

Question 70

The temperature of a gas at 1.00 atm and 8.00 $\degree$ C is increased to 20.0 $\degree$ C, resulting in a change of pressure. What is the new pressure?

A) 0.400 atm.
B) 0.967 atm.
C) 1.00 atm.
D) 1.04 atm.
E) 2.50 atm.

Question 71

What is the volume of 2.01*10 ^{- 3} moles of oxygen at STP?

A) 8.97 * 10 ^{- 5} L
B) 0.00201 L
C) 2.01 *10 ^{- 3} L
D) 4.50 *10 ^{- 2} L
E) 1.11 * 10⁴ L

Question 72

What happens when a large volume of gas is compressed to a smaller volume??

A) There are more gas particles in the same volume.
B) The particles shrink.
C) The gas particles would expand in comparison to the size of the beaker.
D) Compressing the gas would likely result in gas particles lost to the atmosphere.
E) Compressing the gas is just a physical change and so should not effect how the gas particles look.

Question 73

Which statement best describes how the kinetic molecular view of gases can be used to explain the effect of gas temperature on gas pressure?

A) Gas pressure and gas temperature are unrelated.
B) The effect of temperature on pressure depends upon the gas.
C) As temperature increases, the particles are damaged, slowing them down and decreasing the number of collisions against the beaker; therefore the pressure decreases.
D) As temperature increases, the particles are split apart so that there are more collisions against the beaker and the pressure increases.
E) As temperature increases, the speed of particles increases, so there are more collisions against the beaker and the pressure increases.

Question 74

Which of the following statements best describes why a higher concentration of carbon dioxide is present in exhaled breath compared to inhaled breath?

A) Actually, a higher concentration of carbon dioxide is present in inhaled breath.
B) Once the oxygen is used up in an inhalation, a larger percentage is carbon dioxide.
C) The oxygen in inhaled air reacts in the lungs to make carbon dioxide.
D) The concentration of carbon dioxide in the tissue is lower than that in exhaled air.
E) Carbon dioxide is produced during cellular respiration and then carried by the blood to the lungs to be exhaled.

Question 75

Which of the following are ways to increase the pressure of a gas?

A) heating the gas
B) decreasing the volume of the gas by placing it into a smaller container
C) adding more gas molecules to the container
D) compressing the gas
E) All of the above

Question 76

You drive your car from Salt Lake City up into the mountains to go skiing. It is a nice day in Salt Lake, with a temperature of 16 $\degree$ C and an atmospheric pressure of 0.85 atm. Up in the mountains, it is freezing at -1.0 $\degree$ C and an atmospheric pressure of 0.70 atm. If the volume of air in your tires is 12 L when you leave the city, what is it in the mountains?

A) "-0.91 L"
B) "9.3 L"
C) "11 L"
D) "13 L"
E) "14 L"

Question 77

Imagine that you have a beaker of gas molecules. A small volume of the gas in the beaker is enlarged so you can see the gas particles. If all of the gas in the beaker A is transferred to a new beaker half the size of the original beaker, while maintaining the same temperature, which magnified view best represents what the gas would look like?

A)a
B)b
C)c
D)d
E)e

Question 78

Three boxes, each containing molecules in the gas phase, are illustrated below. Which box would you expect to have the highest pressure?

A) A
B) B
C) C
D) A and B have the same highest pressure.
E) A and C have the same highest pressure.

Question 79

Which of the following is the molar volume of a gas at STP?

A) The molar volume depends on the gas.
B) 1 L
C) 1 mole
D) 6.02 * 10²³ L
E) 22.4 L

Question 80

An oxygen tank has a pressure of 12 atm at 295 K. The maximum pressure that the tank can hold is 25 atm. What is the maximum temperature at which the tank can be stored?

A) 610 K
B) 590 K
C) 350 K
D) 140 K
E) 0.98 K