1

Unit 5 Practice QuestionsI. ThermochemistryQuestions 1-3 refer to the following:

(A) Enthalpy change(B) Entropy change(C) Gibbs free energy change(D) Activation energy(E) Specific heat capacity

1. Is the amount of energy that must be added to raise the temperature of 1 gram of a substance to 1oC

2. Its value indicates the spontaneity of a reaction3. Its value indicates whether a reaction is

endothermic or exothermic

2

Questions 1-4 refer to the following:

(A) Positive DH(B) Negative DH(C) Positive DG(D) Negative DG(E) Positive DS

1. Describes a spontaneous reaction2. Describes an endothermic reaction3. Describes a nonspontaneous reaction4. Is multiplied by temperature in the equation that

calculates free energy

3

Questions 1-3 refer to the following:

(A) Gibbs free energy(B) Heat of formation(C) Enthalpy change(D) Entropy(E) Kinetic energy

1. Value that determines whether a reaction is spontaneous

2. Quantity that determines whether a reaction is exothermic or endothermic

3. Indicates the degree of disorder in a system

4

I

An exothermic reaction releases more heat than it absorbs

II

The potential energy of the products is greater than that of the reactants

An exothermic reaction has a negative value for DH

In an exothermic reaction the products have less potential energy than the reactants

BECAUSE

BECAUSE

5

I

If a reaction is exothermic, it always proceeds spontaneously

II

The universe favors a negative enthalpy change

Ice melting is an endothermic process

Heat must be absorbed by ice if it is to melt

BECAUSE

BECAUSE

6

I

An increase in entropy leads to a decrease of randomness

II

The lower energy state of ordered crystals has high entropy

A gas is more random than a liquid

Entropy increases from gas to liquid

BECAUSE

BECAUSE

7

I

An exothermic reaction has a positive DH

II

Heat must be added to the system for the reaction to occur

The entropy of a solid increases when it is dissolved in solvent

It becomes less orderedBECAUSE

BECAUSE

8

I

An endothermic reaction can be spontaneous

II

Both enthalpy and entropy changes affect the value of a reaction’s Gibbs free energy

BECAUSE

When a salt dissolves in water, S for the process is positive

for a salt sample, aqueous ions have a greater entropy than ions in a solid.

BECAUSE

9

I

Exothermic reactions absorb heat

II

Breaking covalent bonds always requires energy.

BECAUSE

When two elements react exothermically to form a compound, the compound should be relatively stable

The release of energy from a combination reaction indicates that the compound formed is at a lower energy level than the reactants and thus relatively stable.

BECAUSE

10

I

If the heat of formation of a compound is a large number preceded by a minus sign, the reaction is exothermic

II

The First Law of Thermodynamics states that a negative heat of formation is associated with an exothermic reaction.

BECAUSE

11

I

The ΔHreaction of a particular reaction can be arrived at by the summation of the ΔHreaction values of two or more reactions that, added together, give the ΔHreaction of the particular reaction

II

Hess’s Law conforms to the First Law of Thermodynamics, which states that the total energy of the universe is a constant.

BECAUSE

12

Which of the following demonstrates a decrease in entropy?

(A) Dissolving a solid into solution(B) An expanding universe(C) Burning a log in a fireplace(D) Raking up leaves into a trash bag(E) Spilling a glass of water

13

When one mole of sulfur burns to form SO2, 1300 calories are released. When one mole of sulfur burns to form SO3, 3600 calories are released. What is the DH when one mole of SO2 is burned to form SO3?

(A) 3900 cal(B) -1950 cal(C) 1000 cal(D) -500 cal(E) -2300 cal

14

10 g of liquid at 300 K is heated to 350 K. The liquid absorbs 6 kcals. What is the specific heat of the liquid (in cal/goC)?

(A) 6(B) 12(C) 60(D) 120(E) 600

15

Which of the following is NOT a true statement about the entropy of a system?

(A) Entropy is a measure of the randomness in a system

(B) The entropy of an amorphous solid is greater than that of a crystalline solid

(C) The entropy of a spontaneous reaction cannot decrease

(D) The entropy of an isolated system will spontaneously increase or remain constant

(E) The entropy of a liquid is generally greater than that of a solid

16

The combustion of octane, C8H18, has DH < 0 and DS > 0. Which of the following statements is FALSE regarding the combustion of octane?

(A) The reaction is spontaneous at room temperature

(B) The reaction is spontaneous at all temperatures(C) The reaction products are carbon dioxide and

water vapor(D) The reaction is a redox process(E) The reaction is endothermic at room

temperature

17

2Na(s) + Cl2 2NaCl(s) + 822 kJ

How much heat is released by the above reaction if 0.5 mole of sodium reacts completely with chlorine?

(A) 205 kJ(B) 411 kJ(C) 822 kJ(D) 1,644 kJ(E) 3,288 kJ

18

This question pertains to the reaction represented by the following equation:

2NO(g) + O2 2NO2(g) + 150 kJ

Suppose that 0.8 mole of NO is converted to NO2 in the above reaction. What amount of heat will be evolved?

(A) 30 kJ(B) 60 kJ(C) 80 kJ(D) 130 kJ(E) 150 kJ

19

Based on the information shown, each of the following equations represents a reaction in which the change in entropy, ΔS, is positive EXCEPT

(A) CaCO3(s) CaO(s) + CO2(g)(B) Zn(s) + 2H+(aq) H2(g) + Zn2+(aq)(C) 2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(g)(D) NaCl(s) Na+(aq) + Cl-(aq)(E) N2(g) + 3H2(g) 2NH3(g)

20

What is the ΔH0 value for the decomposition of sodium chlorate, given the following information?

(ΔH0f values: NaClO3(s) = -358 J/mol,

NaCl(s) = -410 J/mol, O2(g) = 0 J/mol

(A) 52.0 J(B) -52.0 J(C) 768 J(D) -768 J(E) 3 (768 J) 2

21

In the graphic representation of the energy contents of the reactants and the resulting products in an exothermic reaction, the energy content would be

(A) Higher for the reactants(B) Higher for the products(C) The same for both(D) Impossible to determine

22

To heat 10.0 grams of water from 4°C to 14°C requires

(A) 10.0 J(B) 4.18 J(C) 418. J(D) 4180. J

23

A synthesis reaction will occur spontaneously after the activation energy is provided if the heat of formation of the product is

(A) Large and negative (B) Small and negative (C) Large and positive(D) Small and positive

24

Enthalpy is the expression for the

(A) Heat content(B) Energy state(C) Reaction rate(D) Activation energy

25

A ΔHreaction of -100 kJ/mole indicates the reaction is (A) Endothermic (B) Unstable(C) In need of a catalyst(D) exothermic

26

According to the Kinetic-Molecular Theory, molecules increase in kinetic energy when they (A) Are mixed with other molecules at lower

temperature(B) Are frozen into a solid(C) Are condensed into a liquid(D) Are heated to a high temperature(E) Collide with each other in a container at a lower

temperature

27

The two most important considerations in deciding whether a reaction will occur spontaneously are (A) The stability and state of the reactants(B) The energy gained and the heat evolved(C) A negative value for ΔH and a positive value for

ΔS (D) A positive value for ΔH and a negative value for

ΔS(E) The endothermic energy and the structure of

the products

28

Which value best determines whether a reaction is spontaneous?

(A) Change in Gibbs free energy, ΔG(B) Change in entropy, ΔS(C) Change in kinetic energy, ΔKE(D) Change in enthalpy, ΔH(E) Change in heat of formation, ΔH0

f

29

Which of these statements is NOT correct? (A) In an exothermic reaction, ΔH is negative and

the enthalpy decreases. (B) In an endothermic reaction, ΔH is positive and

the enthalpy increases.(C) In a reaction where ΔG is negative, the forward

reaction is spontaneous. (D) In a reaction where ΔG is positive, ΔS may also

be positive. (E) In a reaction where ΔH is positive and ΔS is

negative, the forward reaction is spontaneous.

30

How much heat energy is released when 8 grams of hydrogen are burned? The thermal equation is:

2H2(g) +O2(g) 2H2O(g) + 483.6 kJ (A) 241.8 kJ (B) 483.6 kJ(C) 967.2 kJ(D) 1,934 kJ(E) 3,869 kJ

31

S + O2 SO2 DH = -297 kJ2SO2 + O2 2SO3 DH = -198 kJ

Given the above thermochemical reactions, what is the heat of reaction for the formation of SO3 provided below?

S + 3/2 O2 SO3

(A) -495 kJ(B) -396 kJ(C) -198 kJ(D) +99 kJ(E) +198 kJ

32

Determine the heat of reaction for the combustion of sulfur dioxide:

2SO2 + O2 2SO3

Given the following thermochemical equations:I. S8 + 8O2 8SO2 DH = -2374.6

kJII. S8 + 12O2 8SO3 DH = -

3165.8 kJ

(A) -5540.4 kJ(B) -1385.1 kJ(C) -791.2 kJ(D) -197.8 kJ(E) -791.2 kJ

33

When the temperature of a 20-gram sample of water is increased from 10oC to 30oC, the heat is transferred to the water is

(A) 600 calories(B) 400 calories(C) 200 calories (D) 30 calories(E) 20 calories

34

The change in heat energy for a reaction is best expressed as a change in

(A) Enthalpy (B) Absolute temperature(C) Specific heat(D) Entropy (E) Kinetic energy

35

The heat capacity for aluminum is 0.89 J/goC, for iron is 0.45 J/goC, and for zinc is 0.39 J/goC. If 100 J of heat energy was added to a 10.0 g sample of each of the metals, which of the following would be true?

(A) Al would have the largest temperature increase(B) Fe would have the largest temperature increase(C) Zn would have the largest temperature increase(D) Fe and Zn would have the same temperature

increase(E) All three metals would have the same

temperature increase

36

Which of the following forward processes produces a decrease in entropy?

I. H2O(g) H2O (l)II. Fe2+(aq) + S2- (aq) FeS(s)III. 2SO3(g) 2SO2(g) + O2(g)

(A) I only(B) III only(C) I and II only(D) II and III only(E) I, II, and III

37

If 1 mole of O2(g) is consumed in the reaction given below, how much energy is released?

CH4(g) + 2O2(g) CO2(g) + 2H2O(g) + 800 kJ

(A) 200 kJ(B) 400 kJ(C) 800 kJ(D) 1,200 kJ(E) 1,600 kJ

38

In which of the following processes is entropy increasing?

(A) N2(g) + 3Cl2(g) 2NCl3(g)(B) H2O(g) H2O(l)(C) 2H2O(l) 2H2(g) + O2(g)(D) CO(g) + 2H2(g) CH3OH(l)(E) 2NO2(g) N2O4(g)

39

Which of the following reactions shows a decrease in entropy?

(A) C (s) + 2H2(g) CH4(g)(B) H2O(g) H2(g) + 1/2 O2(g)(C) 2NI3(s) N2(g) + 3I2(g)(D) 2O3(g) 3O2(g)(E) None of the above

40

At which temperature does a water sample have the highest kinetic energy?

(A) 0 degrees Celsius(B) 100 degrees Celsius(C) 0 K(D) 100 K(E) 273 K

41

If the free energy change accompanying a reaction is negative

(A) The reaction can occur spontaneously(B) The reaction can be used to do work by driving

other reactions(C) The entropy must always be negative(D) Both A and B

42

A 50 g sample of metal was heated to 100oC and then dropped into a beaker containing 50 g of water at 25oC. If the specific heat capacity of the metal is 0.25 cal/goC, what is the final temperature of the water?

(A) 27oC(B) 40oC(C) 60oC(D) 86oC

43

How many joules of heat are released by a 150-gram sample of water that cools from 25oC to 5oC? (C for water is 4.18 J/gK)

(A) 78,375 joules(B) 83.6 joules(C) 720 joules(D) 627 joules(E) 12,540 joules

44

Which process below has been described correctly for a temperature above 274K?

(A) H2O(l) H2O(s) is exothermic and spontaneous(B) H2O(l) H2O(s) is endothermic and spontaneous(C) H2O(g) H2O(l) is endothermic and spontaneous(D) H2O(s) H2O(l) is endothermic and spontaneous(E) H2O(s) H2O(l) is exothermic and spontaneous

45

Calculate the heat for the overall reaction:Mg + ½ O2 MgO

Given the heats of reaction below:Mg + 2HCl MgCl2 + H2 DH = -143kJMgO + 2HCl MgCl2 + H2O DH = -216kJH2 + ½ O2 H2O DH = -285kJ

(A) -644 kJ(B) -212 kJ(C) +644 kJ(D) -74 kJ(E) +74 kJ

46

What is the value of DH for the reaction:X + 2Y 2Z

(W + X 2Y DH = -200 kcal)(2W + 3X 2Z + 2Y DH = -150 kcal)

(A) -550 kcal(B) +50 kcal(C) -50 kcal(D) -350 kcal(E) +250 kcal

47

Calculate the enthalpy of formation of a mole of N (g) in the following reaction:

N2 (g) 2N (g)DH = 945.2 kJ

(A) -945.2 kJ/mol(B) 0.0 kJ/mol(C) 472.6 kJ/mol(D) 945.2 kJ/mol

48

Which units could be used to express the amount of energy absorbed or released during a chemical reaction?

(A) Degree and gram(B) Torr and mmHg(C) Gram and liter(D) Calorie and joule(E) Meter and cm3

49

How much heat is required to raise the temperature of 85 grams of water from 280 K to 342 K?

(A) 5,270 J(B) 355 J(C) 259 J(D) 151 J(E) 22,029 J

50

Which set of conditions below guarantees that a reaction will be spontaneous?

( )A DH(+) and DS(-)( )B DH(-) and DS(+)( )C DH(+) and DS(+) at a low temperature( )D DH(-) and DS(+) at a high temperature( )E DG(+)

51

Which statement is incorrect regarding energy?

(A) Energy can be given off in a reaction(B) Energy can be gained in a reaction(C) Energy cannot be created or destroyed(D) Energy can take various forms(E) Energy has mass and takes up space

52

A process involving no heat exchange is known as

(A) An isothermal process(B) An isobaric process(C) An adiabatic process(D) An isometric process

53

What is the heat capacity of a 10 g sample that has absorbed 100 cal over a temperature change of 30oC?

(A) 0.333 cal/goC(B) 0.666 cal/goC(C) 3 cal/goC(D) 300 cal/goC

54

What is the value for DH for the reaction:D + A + B F

(A + B C DH = -390 kJ)(D + ½ B E DH = -280 kJ)(F + ½ B C + E DH = -275 kJ)

(A) -165 kJ(B) +385 kJ(C) -395 kJ(D) -945 kJ(E) +400 kJ

55

From the heats of reaction of these individual reactions:A + B 2 C DH = -500 kJ)(D + 2B E DH = -700 kJ)(2D + 2A F DH = +50 kJ)

Find the heat of reaction for F + 6B 2E + 4C

(A) +450 kJ(B) -1100 kJ(C) +2300 kJ(D) -350 kJ(E) -2450 kJ

56

Which of the following demonstrates DS(-)?

I. Raking up leavesII. Boiling a liquidIII. Emptying a box of confetti onto the floor

(A) I only(B) II only(C) I and II only(D) I and III only(E) II and III only

57

Which process would have a positive value for the change in entropy?

I. The expansion of the universeII. The condensation of a liquidIII. A food fight at a school cafeteria

(A) I only(B) II only(C) III only(D) II and III only(E) I and III only

58

II. Phase Changes

Questions 1-4 refer to the following:(A) Sublimation(B) Deposition(C) Vaporization(D) Condensation(E) freezing

1. Solid to gas2. Gas to solid3. Liquid to gas4. Liquid to solid

59

Questions 1-4 refer to the following:

(A) N2O4(g) + heat 2NO2(g)(B) I2(s) I2(g)(C) CHCl3(l) CHCl3(g)(D) Br2(s) Br2(l)(E) O2(g) O2(l) 1. At constant pressure, requires a decrease in heat to

occur2. Is an example of sublimation3. Produces a decrease in system entropy4. Enthalpy change for the process can equal heat of

fusion for the process

60

Questions 1-3 refer to the following:

(A) Sublimation(B) Condensation(C) Evaporation(D) Deposition(E) Melting 1. Gas solid2. Gas liquid3. Solid gas

61

I

When a sample of water freezes, the process is exothermic

Water boils at a lower temperature at high altitude than at low altitude

II

ice is at a lower potential energy state than water

The vapor pressure of water is lower at higher altitude

BECAUSE

BECAUSE

62

I

A network solid has a high melting point

A pot of water will boil above 100oC at high elevations

II

hydrogen bonds are more difficult to break than covalent bonds

the average kinetic energy of molecules must increase as the pressure on them increases

BECAUSE

BECAUSE

63

I

At 1 atm, pure water can boil at a temperature less than 273K

CO2 is able to sublimate at atmospheric pressure

II

Water boils when the vapor pressure of the water is equal to the atmospheric pressure

Its liquid form is impossible to produce

BECAUSE

BECAUSE

64

I

As ice absorbs heat and begins to melt, its temperature remains constant

II

The absorbed heat is consumed by the breaking of intermolecular reactions

BECAUSE

320 calories or 1.34 × 103 joules of heat will melt 4 grams of ice at 0°C

The heat of fusion of water is 80 calories per gram or 3.34 × 102 joules per gram.

BECAUSE

65

The process in which water vapor changes phase to become a liquid is called

(A) Deposition(B) Sublimation(C) Vaporization(D) Fusion(E) Condensation

66

Which of the following indicates the relative randomness of molecules in the three states of matter?

(A) Solid > liquid > gas(B) Liquid < solid < gas(C) Liquid > gas > solid(D) Gas > liquid > solid(E) None of the above

67

Which of the following generalizations CANNOT be made about the phase change of a pure substance from solid to liquid?

(A) It involves a change in potential energy(B) It involves no change in temperature(C) It involves a change in kinetic energy(D) It involves a change in entropy(E) It may occur at different temperatures for

different compounds

68

A substance possessing a characteristically low vapor pressure can be expected to have

(A) Extremely weak intermolecular forces(B) A relatively small heat of vaporization (C) A relatively high boiling point (D) A relatively high rate of evaporation(E) A significantly high percentage of molecules

that have high kinetic energy

69

What is the correct term for the phase change from gas directly to solid?

(A) Deposition(B) Sublimation(C) Liquefaction(D) Fusion(E) Vaporization

70

If 10.0 grams of ice melts at 0°C, the total quantity of heat absorbed is

(A) 10.0 J(B) 334 J(C) 3,340 J(D) 33,400 J

71

A liquid will boil when

(A) Enough salt has been added to it(B) The vapor pressure of the liquid is equal to the

atmospheric or surrounding pressure(C) The vapor pressure of the liquid reaches 760

mmHg(D) Conditions favor the liquid’s molecules to be

closer together(E) It has been brought up to a higher elevation

72

Calculate the number of joules required to completely evaporate 18 grams of water at 98oC. (Hv = 2259 J/g and C = 4.18 J/gK)

(A) 40812 joules(B) 40512 joules(C) 150 joules(D) 40662 joules(E) 6.12 x 106 joules

73

Which sample demonstrates particles arranged in a regular geometric pattern?

(A) CO2(g)

(B) CO2(s)

(C) CO2(l)

(D) CO2(aq)

(E) None of the above

74

Which phase change is described correctly?

(A) Solid to gas is called deposition(B) Gas to solid is called sublimation(C) Liquid to solid is called freezing(D) Solid to liquid is called vaporization(E) Liquid to gas is called condensation

75

A solid, liquid and gas can exist together at the

(A) Sublimation point(B) Triple point(C) Boiling point(D) Freezing point(E) Melting point

76

Which of the following solids are known to undergo sublimation?

I. CO2

II. I2

III. naphthalene

(A) I only(B) II only(C) I and II only(D) II and III only(E) I, II and III

77

Refer to the following choices:

I. solid to liquidII. Liquid to gasIII. Solid to gas

Which phase change above is endothermic?

(A) I only(B) II only(C) III only(D) II and III only(E) I, II and III

78

III. Gases

Questions 1-4 refer to the following:(A) Boyle’s Law(B) Charles’ Law(C) Avogadro’s Principle(D) Ideal Gas Law(E) Dalton’s Law

1. Total pressure of a gaseous mix is equal to the sum of the partial pressures

2. Volume is inversely proportional to pressure3. Volume is directly proportional to temperature4. All gases have the same number of moles in the

same volume at constant temperature and pressure

79

Questions 1-3 refer to the following:

(A) He at 100oC and 1 atm(B) He at 25oC and 1 atm(C) Ar at 25oC and 1 atm(D) Ar at 25oC and 2 atm(E) Ar at 0oC and 1 atm

1. Has the highest molecular speed2. Has the lowest kinetic energy3. Occupies the largest volume

80

I

Increasing the pressure on a gas forces the gas to occupy a smaller volume

II

Gases are compressible

The relationship between pressure and volume is considered to be an inverse relationship

As pressure increases on a gas, the volume of the gas will decrease

BECAUSE

BECAUSE

81

I

Nitrogen gas will have a greater rate of effusion than oxygen gas

II

Lighter, less dense gases travel faster than heavier, more dense gases

The ideal gas law does not hold under low temperatures and high pressure

Interactions between particles cannot be neglected under these conditions

BECAUSE

BECAUSE

82

I

When an ideal gas is cooled, its volume will increase

In the kinetic theory of gases, collisions between gas particles and the walls of the container are considered elastic

II

Temperature and volume are proportional

Gas molecules are considered pointlike, volumeless particles with no intermolecular forces and in constant, random motion

BECAUSE

BECAUSE

83

A gas heated from 10°C to 100°C at constant pressure will increase in volume

As Charles’s Law states, if the pressure remains constant, the volume varies directly as the absolute temperature varies.

BECAUSE

BECAUSE

I

Hydrogen gas (H2) is considered a perfectly ideal gas

II

hydrogen atoms interact with each other via hydrogen bonds

84

I

If an ideal gas is located in a closed container and temperature is increased, the average speed of the molecules will always increase as well

II

For an ideal gas, temperature and moles of gas are inversely proportional.

BECAUSE

85

I

For an ideal gas, pressure and volume have no relationship

II

according to the ideal gas law, temperature and volume are directly proportional when other variables are held constant.

BECAUSE

At isothermal and isobaric conditions, helium effuses faster than neon

Neon has a higher molar mass than helium

BECAUSE

86

If the pressure of a gas is doubled at constant temperature, the volume will be

(A) 4 times the original(B) 2 times the original(C) ½ of the original(D) ¼ of the original(E) 1/8 of the original

87

Given equal conditions, which gas below is expected to have the greatest rate of effusion?

(A) H2

(B) Ar(C) Kr(D) F2

(E) Cl2

88

Which fraction would be used to find the new volume of a gas at 760 torr under its new pressure at 900 torr if the temperature is kept constant?

(A) 900/760(B) 1.18(C) 760/900(D) 658.7/798.7(E) 798.7/658.7

89

Which of the following statements is not part of the kinetic molecular theory?

(A) The average kinetic energy of gas molecules is proportional to temperature

(B) Attractive and repulsive forces are present between gas molecules

(C) Collisions between gas molecules are perfectly elastic

(D) Gas molecules travel in a continuous, random motion

(E) The volume that gas molecules occupy is minimal compared to the volume in which the gas is contained

90

What is the volume of 2.3 moles of an ideal gas at 300 K and a pressure of 1.1 atmospheres?

(A) (2.3 moles)(0.0820 Latm/molK)(300 K)(1.1 atm)

(B) (1.1 atm)

(2.3 moles)(0.0820 Latm/molK)(300 K)(C) (2.3 moles)(0.0820 Latm/molK)

(300 K)(1.1 atm)(D) (300 K)(0.0820 Latm/molK)

(2.3 moles)(1.1 atm)(E) (2.3 moles)(1.1 atm)(300 K)

(0.0820 Latm/molK)

91

One mole of an ideal gas at STP has its temperature changed to 15oC and its pressure changed to 700 torr. What is the new volume of this gas?

(A) (760 torr)(22.4 L)(288 K)(273 K)(700 torr)

(B) (273 K)(700 torr)

(760 torr)(22.4 L)(288 K)(C) (760 torr)(22.4 L)(273 K)

(288 K)(700 torr)(D) (700 torr)(22.4 L)(287 K)

(273 K)(760 torr)(E) (760 torr)(1.0 L)(288 K)

(273 K)(700 torr)

92

Ideal gases

(A) Have forces of attraction between them(B) Are always linear in shape(C) Never travel with a straight line motion(D) Have molecules that are close together(E) Have low masses and are spread far apart

93

A mixture of gases exists in a sealed container with the following percentages: helium 40%, neon 50%, argon 10%. If the total pressure of the gases is 1100 torr, then which of the following is true about these gases?

(A) Volume and temperature have an inversely proportional relationship

(B) Volume and pressure have a direct relationship(C) The partial pressure of the neon gas is 550 torr(D) The partial pressure of the argon gas is 100 torr(E) The partial pressures of the gases cannot be

calculated with the given information

94

An ideal gas at STP occupies 22.4 liters. If the pressure on the gas is increased to 1000 torr and the temperature of the gas is reduced to 250 K, what can be said about the gas?

(A) The number of moles of gas has changed(B) The volume of the gas has increased(C) The volume of the gas has decreased(D) The pressure and the temperature have an

inversely proportional relationship(E) None of the above

95

Which is inconsistent with the Kinetic Molecular Theory?

(A) Gas molecules have forces of attraction for each other

(B) Gas molecules move in a random, straight-line motion

(C) Gas molecules have a negligible volume compared to the volume they occupy

(D) Collisions between gas molecules lead to a transfer of energy that is conserved

(E) All of the above statements are correct

96

Which laws can be used to calculate changes in volume with changes in pressure at constant temperature?

I. Boyle’s LawII. Charles’ LawIII. Combined Gas Law

(A) I only(B) II only(C) II and III only(D) I and III only(E) I and II only

97

Inelastic collisions occur in

I. Real gasesII. Ideal gasesIII. Fusion reactions

(A) I and II(B) II and III(C) I and III (D) I only(E) II only

98

When a fixed amount of gas has its Kelvin temperature doubled and its pressure doubled, the new volume of the gas is

(A) Four times greater than its original volume (B) Twice its original volume(C) Unchanged (D) One-half its original volume(E) One-fourth its original volume

99

A flask contains three times as many moles of H2 gas as it does O2 gas. If hydrogen and oxygen are the only gases present, what is the total pressure in the flask if the partial pressure due to oxygen is P?

(A) 4P(B) 3P(C) 4/3 P(D) ¾ P(E) 7P

100

Boyle’s Law can be used for which of the following?

(A) Predicting the expected volumes of two party balloons

(B) Predicting the relative pressures inside a hot air balloon

(C) Predicting the change in volume of an inflatable toy from summer to winter

(D) Predicting the height of a mercury barometer column in a low-pressure system

(E) Predicting the change in volume of a party balloon inside a bell jar as a vacuum is being drawn

101

A sample of argon occupies 50 L at standard temperature. Assuming constant pressure, what volume will the gas occupy if the temperature is doubled?

(A) 25L(B) 50L(C) 100L(D) 200L(E) 2500L

102

All of the following statements underlie the kinetic molecular theory of gases EXCEPT:

(A) Gas molecules have no intermolecular forces(B) Gas particles are in random motion(C) The collisions between gas particles are elastic(D) Gas particles have no volume(E) The average kinetic energy is proportional to the

temperature (oC) of the gas

103

A 600-milliliter container holds 2 moles of O2(g), 3 moles of H2(g), and 1 mole of He(g). Total pressure within the container is 760 torr. What is the partial pressure of O2?

(A) 127 torr(B) 253 torr(C) 380 torr(D) 507 torr(E) 760 torr

104

Which of the gases below has the greatest average kinetic energy at 25oC and 1 atm?

(A) Ne(B) Ar(C) CO(D) CO2

(E) All these gases would have the same average kinetic energy under these conditions

105

If one mole of a gas originally at STP is placed in a container where the pressure is doubled and the temperature in K is tripled, what is the new volume in L?

(A) 2.2(B) 5.6(C) 7.5(D) 11.2(E) 33.6

106

An ideal gas has a volume of 10 liters at 20oC and a pressure of 750 mmHg. Which of the following expressions is needed to determine the volume of the same amount of gas at STP?

107

An ideal gas in a closed inflexible container has a pressure of 6 atmospheres and a temperature of 27oC. What will be the new pressure of the gas if the temperature is decreased to -73oC?

(A) 2 atm(B) 3 atm(C) 4 atm(D) 8 atm(E) 9 atm

108

Equal molar quantities of hydrogen gas and oxygen gas are present in a closed container in a constant temperature. Which of the following quantities will be the same for the two gases?

I. Partial pressureII. Average kinetic energyIII. Average molecular velocity

(A) I only(B) I and II only(C) I and III only(D) II and III only(E) I, II, and III

109

Questions 1-3 pertain to the following situation.A closed 5-liter vessel contains a sample of neon gas. The temperature inside the container is 25oC, and the pressure is 1.5 atmospheres. (The gas constant, R, is equal to 0.08 L-atm/mol-K.)

1. Which of the following expressions is equal to the molar quantity of gas in the sample?

110

2. If the neon gas in the vessel is replaced with an equal molar quantity of helium gas, which of the following properties of the gas in the container will be changed?

I. Pressure II. TemperatureIII. Density

(A) I only(B) I and II only(C) III only(D) I and II only(E) II and III only

111

3. The volume of the vessel was gradually changed while temperature was held constant until the pressure was measure at 1.6 atmospheres. Which of the following expressions is equal to the new volume?

112

According to the ideal gas law, what is the approximate volume that will be occupied by 0.5 mole of an ideal gas at 30oC and 3 atm pressure (gas constant R = 0.0821 Latm/molK)?

(A) Less than 1 L(B) 5 L (C) 10 L(D) 15 L(E) More than 20 L

113

A liter of hydrogen is at 5.0°C temperature and under 640. torr pressure. If the temperature were raised to 60.0°C and the pressure decreased to 320. torr, how would the liter volume be modified?

114

Standard conditions (STP) are

(A) 0°C and 2 atm(B) 32°F and 76 torr(C) 273 K and 760 mm Hg(D) 4°C and 7.6 cm Hg(E) 0 K and 760 mm Hg

115

What is the boiling point of water at the top of Pikes Peak?

(A) It is 100°C. (B) It is > 100°C since the pressure is less than at

ground level.(C) It is < 100°C since the pressure is less than at

ground level.(D) It is > 100°C since the pressure is greater than at

ground level. (E) It is < 100°C since the pressure is greater than at

ground level.

116

Graham’s Law refers to

(A) Boiling points of gases(B) Gaseous diffusion (C) Gas compression problems(D) Volume changes of gases when the temperature

changes

117

When 200 milliliters of a gas at constant pressure is heated, its volume

(A) Increases(B) Decreases(C) Remains unchanged

118

When 200 milliliters of a gas at constant pressure is heated from 0°C to 100°C, the volume must be multiplied by

(A) 0/100(B) 100/0(C) 273/373(D) 373/273

119

At 5.00 atmospheres pressure and 70°C how many moles are present in 1.50 liters of O2 gas?

(A) 0.036(B) 0.266(C) 0.536(D) 0.103