1.Which event must always occur for a chemical reaction 8

A) formation of a precipitateB) formation of a gasC) effective collisions between reacting particlesD) addition of a catalyst to the reaction system

1. Which event must always occur for a chemical reactionto take place?

A) The activation energy of the reaction increases.B) The activation energy of the reaction decreases.C) The number of molecules with sufficient energy

to react increases.D) The number of molecules with sufficient energy to

react decreases.

2. Why can an increase in temperature lead to moreeffective collisions between reactant particles and anincrease in the rate of a chemical reaction?

A) fewer particle collisions occurB) more effective particle collisions occurC) the required activation energy increasesD) the concentration of the reactants increases

3. As the temperature of a chemical reaction in the gasphase is increased, the rate of the reaction increasesbecause

A) standard temperature and pressureB) a catalyst added to the reaction systemC) effective collisions between reactant particlesD) an equal number of moles of reactants and products

4. What is required for a chemical reaction to occur?

A) proper energy, onlyB) proper orientation, onlyC) both proper energy and proper orientationD) neither proper energy nor proper orientation

5. A reaction is most likely to occur when reactant particlescollide with

A) potential energy B) kinetic energyC) activation energy D) ionization energy

6. The energy needed to start a chemical reaction is called

A) the particles are heatedB) the atmospheric pressure decreasesC) there is a catalyst presentD) there are effective collisions between the particle

7. A chemical reaction between iron atoms and oxygenmolecules can only occur if

A) are activated by heat from the Bunsen burnerflame

B) are activated by heat from the burning magnesiumC) underwent an increase in entropyD) underwent a decrease in entropy

8. A piece of Mg(s) ribbon is held in a Bunsen burner flameand begins to burn according to the equation:

2Mg(s) + O2 (g) ® 2MgO(s).

The reaction begins because the reactants

A) a decrease in the concentration of the reactantsB) a decrease in the surface area of the productsC) an increase in the temperature of the systemD) an increase in the activation energy of the forward

reaction

9. For a reaction at equilibrium, which change can increasethe rates of the forward and reverse reactions?

A) LiBr B) NaClC) NaOH D) NH4Cl

10. At 101.3 kPa and 298 K, a 1.0-mole sample of whichcompound absorbs the greatest amount of heat as theentire sample dissolves in water?

A) 25ºC B) 50ºCC) 75ºC D) 100ºC

11. Given the reaction:

Mg + 2 H2O ® Mg(OH)2 + H2At which temperature will the reaction occur at thegreatest rate?

A) a zinc strip and 1.0 M HCl(aq)B) a zinc strip and 3.0 M HCl(aq)C) zinc powder and 1.0 M HCl(aq)D) zinc powder and 3.0 M HCl(aq)

12. A 5.0-gram sample of zinc and a 50.-milliliter sampleof hydrochloric acid are used in a chemical reaction.Which combination of these samples has the fastestreaction rate?

A) 1.0 M HCl(aq) at 20.°CB) 1.0 M HCl(aq) at 40.°CC) 2.0 M HCl(aq) at 20.°CD) 2.0 M HCl(aq) at 40.°C

13. A 1.0-gram piece of zinc reacts with 5 milliliters ofHCl(aq). Which of these conditions of concentrationand temperature would produce the greatest rate ofreaction?

A) decreases B) increasesC) remains the same

14. As the concentration of reacting particles increases, therate of reaction generally

A) lower kinetic energyB) lower concentrationC) more surface areaD) more zinc atoms

15. Given the reaction at 25°C:

Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)The rate of this reaction can be increased by using 5.0grams of powdered zinc instead of a 5.0-gram strip ofzinc because the powdered zinc has

A) a decrease in the rate of the reactionB) an increase in the rate of the reactionC) a decrease in the heat of reactionD) an increase in the heat of reaction

16. An increase in the surface area of reactants in aheterogeneous reaction will result in

A) acts as a better catalyst than the single piece ofiron

B) absorbs less energy than the single piece of ironC) has a greater surface area than the single piece

of ironD) is more metallic than the single piece of iron

17. Given the balanced equation representing a reaction:

Fe(s) + 2HCl(aq) FeCl2 (aq) + H2(g)

This reaction occurs more quickly when powdered ironis used instead of a single piece of iron of the samemass because the powdered iron

A) slower because organic particles are ionsB) slower because organic particles contain

covalent bondsC) faster because organic particles are ionsD) faster because organic particles contain covalent

bonds

18. Compared to the rate of inorganic reactions, the rate oforganic reactions generally is

A) A catalyst is added as an additional reactant and isconsumed but not regenerated.

B) A catalyst limits the amount of reactants used.C) A catalyst changes the kinds of products produced.D) A catalyst provides an alternate reaction

pathway that requires less activation energy.

19. Which statement best explains the role of a catalyst in achemical reaction?

A) faster, because the organic particles are ionsB) faster, because the organic particles are moleculesC) slower, because the organic particles are ionsD) slower, because the organic particles are

molecules

20. Compared with the rate of an inorganic reaction, therate of an organic reaction is usually

A) endothermic B) exothermicC) spontaneous D) redox

21. In what type of reaction do the products of the reactionalways possess more potential energy than thereactants?

A) It is endothermic and entropy increases. B) It is endothermic and entropy decreases.C) It is exothermic and entropy increases. D) It is exothermic and entropy decreases.

22. Given the balanced equation:

Which statement best describes this process?

A) The entropy of the LiBr(aq) is greater than theentropy of the water.

B) The entropy of the LiBr(aq) is less than theentropy of the water.

C) The dissolving of the LiBr(s) in water is anendothermic process.

D) The dissolving of the LiBr(s) in water is anexothermic process.

23. A thermometer is in a beaker of water. Which statementbest explains why the thermometer reading initiallyincreases when LiBr(s) is dissolved in the water?

A) involved in the formation of an acidic solutionB) involved in the formation of a basic solutionC) an exothermic reactionD) an endothermic reaction

24. A student observed that the temperature of waterincreased when a salt was dissolved in it. The studentshould conclude that dissolving the salt was

A) The dissolving of only salt A was endothermic.B) The dissolving of only salt B was exothermic.C) The dissolving of both salt A and salt B was

endothermic.D) The dissolving of salt A was exothermic and the

dissolving of salt B was endothermic.

25. Salt A and salt B were dissolved separately in100-milliliter beakers of water. The water temperatureswere measured and recorded as shown in the tablebelow. Salt A Salt B Initial water temperature: 25.1ºC 25.1ºCFinal water temperature: 30.2ºC 20.0ºCWhich statement is a correct interpretation of thesedata?

A) nitrogen (II) oxide (g)B) ethyne (g)C) water (g)D) hydrogen iodide (g)

26. According to Reference Table I, heat is liberated duringthe formation of the compound

A) 50 kJ B) 20 kJ C) 30 kJ D) 80 kJ

27. Assume that the potential energy of the products in achemical reaction is 60 kiloJoules. This reaction wouldbe exothermic if the potential energy of the reactantswere

A) heat of deposition B) heat of fusionC) heat of reaction D) heat of vaporization

28. Which term refers to the difference between thepotential energy of the products and the potentialenergy of the reactants for any chemical change?

A) NaOH(s) ® Na+(aq) + OH–(aq)B) NH4Cl(s) ® NH4+(aq) + Cl–(aq)C) CO(g) + O2(g) ® CO2(g)D) CH4(g) + 2 O2(g) ® CO2(g) + 2 H2O( )

29. Based on Reference Table I, which reaction isendothermic?

A) –571.6 kJ B) –483.6 kJC) –55.8 kJ D) +571.6 kJ

30. According to Reference Table I, what is the heat ofreaction for the formation of two moles of H2O( ) fromhydrogen and oxygen gas at 1 atmosphere and 298 K?

A) NO(g) B) NO2(g)C) C2H4(g) D) C2H6(g)

31. According to Reference Table U, which gas is formedfrom its elements by a spontaneous reaction?

A) A B) B C) C D) D

32. In the potential energy diagram below, which letterrepresents the potential energy of the activatedcomplex?

A) B)

C) D)

33. When a spark is applied to a mixture of hydrogen andoxygen, the gases react explosively. Which potentialenergy diagram best represents the reaction?

A) The activation energy is 10. kJ and the reaction isendothermic.

B) The activation energy is 10. kJ and the reactionis exothermic.

C) The activation energy is 50. kJ and the reaction isendothermic.

D) The activation energy is 50. kJ and the reaction isexothermic.

34. Given the potential energy diagram for a chemicalreaction:

Which statement correctly describes the energy changesthat occur in the forward reaction?

A)

B)

C)

D)


S(s) + O2(g) SO2(g) + energyWhich diagram best represents the potential energychanges for this reaction?

A) A B) B C) C D) D

36. The potential energy diagram below represents areaction.

Which arrow represents the activation energy of theforward reaction?

37. Base your answer to the following question on thepotential energy diagram below, which represents thereaction:

A + B ® C + energy.

A) 1 B) 2 C) 3 D) 4

Which numbered interval will change with the additionof a catalyst to the system?

A) A B) B C) C D) D

38. The potential energy diagram of a chemical reaction isshown below.

Which letter in the diagram represents the heat ofreaction ( H)?

A) 20. kcal B) 40. kcalC) 60. kcal D) 80. kcal

39. A potential energy diagram of a chemical reaction isshown below.

What is the difference between the potential energy ofthe reactants and the potential energy of the products?

A) faster and more reactant is producedB) faster and more product is producedC) the same and the reaction has stoppedD) the same and the reaction continues in both

directions

40. A chemical reaction is at equilibrium. Compared to therate of the forward reaction, the rate of the reversereaction is

A) decreasing B) increasingC) equal D) constant

41. Given the reaction system in a closed container atequilibrium and at a temperature of 298 K:

N2O4(g) 2NO2(g)The measurable quantities of the gases at equilibriummust be

A) SO2(g) must equal the concentration of SO3(g)B) SO2(g) must be constantC) O2(g) must equal the concentration of SO2(g)D) O2(g) must be decreasing

42. Given the equation representing a system atequilibrium:

2SO2(g) + O2(g) 2SO3(g)

At equilibrium, the concentration of

A) a gas is formedB) water is formedC) a weak acid is formedD) a precipitate is formed

43. When AgNO3(aq) is mixed with NaCl(aq), a reactionoccurs which tends to go to completion and not reachequilibrium because

A) The rate of dissolving is equal to the rate ofcrystallization.

B) The rate of dissolving is greater than the rate ofcrystallization.

C) The concentration of the solid is equal to theconcentration of the solution.

D) The concentration of the solid is greater than theconcentration of the solution.

44. Some solid KNO3 remains at the bottom of a stopperedflask containing a saturated KNO3(aq) solution at 22°C.Which statement explains why the contents of the flaskare at equilibrium?

A) decreases, and the amount of AgCl(s) increasesB) decreases, and the amount of AgCl(s) decreasesC) increases, and the amount of AgCl(s) increasesD) increases, and the amount of AgCl(s) decreases

45. Given the equation representing a system atequilibrium:

When the concentration of Cl– (aq) is increased, theconcentration of Ag+ (aq)

A) dissolving stops occurringB) crystallization stops occurringC) both dissolving and crystallization stops occurringD) dissolving occurs at the same rate that

crystallization occurs


AgI(s) « Ag+(aq) + I–(aq)

Solution equilibrium is reached in the system when

A) 100 K B) 273 KC) 298 K D) 373 K

47. Given the equilibrium at 101.3 kPa:

H2O(s) « H2O( )

At what temperature does this equilibrium occur?

A) Only evaporation occurs, but it eventually stops.B) Only condensation occurs, but it eventually stops.C) Neither evaporation nor condensation occurs.D) Both evaporation and condensation occur.

48. Which description applies to a system in a sealed flaskthat is half full of water?

A) Keq = 1.0 × 10–10 B) Keq = 1.0 × 100

C) Keq = 1.0 × 101 D) Keq = 1.0 × 1010

49. Given the reaction at equilibrium:

A(g) « B(g) + C( )

Which equilibrium constant indicates an equilibriummixture with the smallest concentration of B(g)?

A) [H2] × [I2] > [HI]B) [H2] × [I2] < [HI]C) [H2], [I2], and [HI] are all equal.D) [H2], [I2], and [HI] remain constant.

50. Given the equation:

H2(g) + I2(g) « 2 HI(g)

Which statement is always true when this reaction hasreached chemical equilibrium?

A) increasing the concentration of A 2(g)B) decreasing the concentration of B 2(g)C) increasing the temperatureD) decreasing the pressure


A2(g) + 3 B2(g) « 2 AB3(g) + heat

Which change will affect the equilibrium constant forthis reaction?

A) decreasing the concentration of SO2(g)B) decreasing the concentration of O2(g)C) increasing the pressureD) increasing the temperature


2 SO2(g) + O2(g) « 2 SO3(g) + heat

The concentration of SO3(g) may be increased by



H2(g) + Cl2(g) « 2 HCl(g)

As the pressure increases at constant temperature, thenumber of moles of HCl

A) an increase in pressureB) a decrease in pressureC) removal of N2(g)D) removal of H2(g)

54. Ammonia is produced commercially by the Haberreaction:

N2(g) + 3 H2(g) « 2 NH3(g) + heat

The formation of ammonia is favored by

A) decrease B) increaseC) remain the same


4 HCl(g) + O2(g) « 2 Cl2(g) + 2 H2O(g)

If the pressure on the system is increased, theconcentration of Cl2(g) will

A) changing the pressureB) changing the temperatureC) changing the concentration of H2(g)D) changing the concentration of HF(g)

56. Given the system at equilibrium:

H2(g) + F2(g) 2 HF(g) + heat

Which change will not shift the point of equilibrium?

A) shift the equilibrium to the rightB) shift the equilibrium to the leftC) increase the rate of forward and reverse

reactions equallyD) have no effect on the forward or reverse reactions


A(g) + B(g) C(g) + D(g)The addition of a catalyst will

A) The equilibrium concentration of AB will increase.B) The equilibrium concentration of AB will

decrease.C) The rates of the forward and reverse reactions

will change.D) The equilibrium constant for the reaction will

change.

58. What will happen if a catalyst is added to the system atequilibrium?

A + B « AB

A) The equilibrium shifts to the left, and theconcentration of N2(g) decreases.

B) The equilibrium shifts to the left, and theconcentration of N2(g) increases.

C) The equilibrium shifts to the right, and theconcentration of N2(g) decreases.

D) The equilibrium shifts to the right, and theconcentration of N2(g) increases

59. Given the equation representing a reaction atequilibrium:

N2(g) + 3H2(g) 2NH3(g)

What occurs when the concentration of H2(g) isincreased?

A) decreasing the pressureB) decreasing the concentration of N2(g)C) increasing the concentration of O2(g)D) increasing the temperature


N2(g) + O2(g) + energy 2 NO(g)Which change will result in a decrease in the amount ofNO(g) formed?

A) decreasing the concentration of A 2(g)B) increasing the concentration of B 2(g)C) decreasing the pressureD) increasing the temperature


A2(g) + B2(g) « 2 AB(g) + heat

Which stress on the system at equilibrium will increasethe concentration of AB(g)?

A) decreasing the pressure and decreasing theconcentration of N2(g)

B) decreasing the pressure and increasing theconcentration of N2(g)

C) increasing the pressure and decreasing theconcentration of N2(g)

D) increasing the pressure and increasing theconcentration of N2(g)


N2(g) + 3 H2(g) 2 NH3(g) + heat

At constant temperature, which changes would producea greater yield of NH3(g)?

A) activation energy decreasesB) activation energy increasesC) frequency of effective collisions decreasesD) frequency of effective collisions increases

63. Given the balanced equation representing a reaction:

2HCl(aq) + Na2S2O3(aq) S(s) + H2SO3(aq) + 2NaCl(aq)Decreasing the concentration of Na2S2O3(aq) decreases the rate of reaction because the

A) increasing the temperatureB) increasing the concentration of O2(g)C) decreasing the pressureD) decreasing the concentration of SO2(g)


2 SO2(g) + O2(g) « 2 SO3(g) + 44 kcal

Which change will increase the concentration of SO3(g)?

A) reactants, onlyB) products, onlyC) both reactants and productsD) neither reactants nor products


2 CO(g) + O2(g) « 2 CO2(g)

When the reaction is subjected to stress, a change willoccur in the concentration of

A) a decrease in pressureB) an increase in temperatureC) a decrease in the concentration of Ag+ (aq)D) an increase in the concentration of Cl– (aq)

66. A saturated solution is represented by the equation

AgCl(s) + heat « Ag+ (aq) + Cl– (aq).

Which change will cause an increase in the amount ofAgCl(s)?

A) The rate of the forward reaction increases andthe concentration of N2(g) decreases.

B) The rate of the forward reaction decreases and theconcentration of N2(g) increases.

C) The rate of the forward reaction and theconcentration of N2(g) both increase.

D) The rate of the forward reaction and theconcentration of N2(g) both decrease.


N2(g) + 3H2(g) 2NH3(g) + 91.8kJWhat occurs when the concentration of H2(g) isincreased?

A) The equilibrium will shift to the left, and theconcentration of NO2(g) will decrease.

B) The equilibrium will shift to the left, and theconcentration of NO2(g) will increase.

C) The equilibrium will shift to the right, and theconcentration of NO2(g) will decrease.

D) The equilibrium will shift to the right, and theconcentration of NO2(g) will increase.


N2O4(g) + 58.1 kJ 2 NO2(g)What will be the result of an increase in temperature atconstant pressure?

A) increase the percent yield of nitrogenB) increase the rate of formation of ammoniaC) affect the forward reaction rate mostD) affect the reverse reaction rate least

69. Given the reaction for the Haber process:

N2 + 3 H2 « 2 NH3 + heat

The temperature of the reaction is raised in order to

A) endothermic reaction and decreases its rateB) endothermic reaction and increases its rateC) exothermic reaction and decreases its rateD) exothermic reaction and increases its rate

70. An increase in the temperature of a system atequilibrium favors the

A) temperature increasesB) temperature decreasesC) pressure increasesD) pressure decreases


The equilibrium will shift to the right if the

A) The equilibrium will shift to the left and [H2] willincrease.

B) The equilibrium will shift to the left and [H2] willdecrease.

C) The equilibrium will shift to the right and [HI]will increase.

D) The equilibrium will shift to the right and [HI] willdecrease.

72. Given the equilibrium reaction in a closed system:

H2(g) + I2(g) + heat 2 HI(g)What will be the result of an increase in temperature?

A) low temperature and high pressureB) low temperature and low pressureC) high temperature and high pressureD) high temperature and low pressure

73. Given the equilibrium system:

2 A(g) + B(g) + 10 kcal « C(g)

Which conditions would yield the most product?

A) decreasing the concentration of HI(g)B) decreasing the temperatureC) increasing the concentration of I2(g)D) increasing the pressure

74. Given the equation representing a reaction atequilibrium:

H2(g) + I2(g) + heat 2HI(g)Which change favors the reverse reaction?

A) right and the concentration of AgCl(s) willdecrease

B) right and the concentration of AgCl(s) willincrease

C) left and the concentration of Ag+(aq) willdecrease

D) left and the concentration of Ag+(aq) will increase


AgCl(s) « Ag+(aq) + Cl–(aq)

When NaCl(s) is added to the system, the equilibriumwill shift to the

A) The amount of CaSO4(s) will decrease, and the concentration of Ca2+(aq) will decrease.

B) The amount of CaSO4(s) will decrease, and the concentration of Ca2+(aq) will increase.

C) The amount of CaSO4(s) will increase, and the concentration of Ca2+(aq) will decrease.

D) The amount of CaSO4(s) Will increase, and theconcentration of Ca2+(aq) will increase.

76. Given the solution at equilibrium:

CaSO4(s) Ca2+ (aq) + SO42-(aq)

When Na2SO4 is added to the system, how willthe equilibrium shift?

A) decrease as the amount of AgCl(s) decreasesB) decrease as the amount of AgCl(s) increasesC) increase as the amount of AgCl(s) decreasesD) increase as the amount of AgCl(s) increases

77. Given the equation:

As NaCl(s) dissolves in the solution, temperatureremaining constant, the Ag+(aq) concentration will

A) right and the concentration of Ag+ will decreaseB) right and the concentration of Ag+ will increaseC) left and the concentration of Ag+(aq) will

decreaseD) left and the concentration of Ag+(aq) will increase


AgCl(s) « Ag+(aq) + Cl–(aq)

When 0.1 M HCl is added to the system, the point ofequilibrium will shift to the

A) CO2(g) ® CO2(s)B) H2O( ) ® H2O(s)C) Ca(s) + 2 H2O( ) ® Ca(OH)2(aq) + H2(g)D) NaCl(aq) + AgNO3(aq) ® AgCl(s) + NaNO3(aq)

79. Which reaction results in an increase in entropy?

A) gas to a liquid B) gas to a solidC) liquid to a gas D) liquid to a solid

80. The entropy of a sample of H2O increases as the samplechanges from a

A) lower energy and lower entropyB) lower energy and higher entropyC) higher energy and lower entropyD) higher energy and higher entropy

81. Systems in nature tend to undergo changes toward


82. As the reactants are converted to product in the reaction

A(g) + B(g) ® C(s),

the entropy of the system

A) exothermic with an increase in entropyB) exothermic with a decrease in entropyC) endothermic with an increase in entropyD) endothermic with a decrease in entropy

83. Which phrase best describes the reaction below?

A) lower energy and less disorderB) lower energy and more disorderC) higher energy and less disorderD) higher energy and more disorder

84. Systems in nature tend to undergo changes toward

A) Br2(s) at 266 K B) Br2( ) at 266 KC) Br2( ) at 332 K D) Br2(g) at 332 K

85. Which 1-mole sample has the least entropy?

A) lower potential energy and less randomnessB) lower potential energy and more randomnessC) greater potential energy and less randomnessD) greater potential energy and more randomness

86. A reaction will be spontaneous if it results in productsthat have

A) spontaneous, with a negative DGB) spontaneous, with a positive DGC) non-spontaneous, with a negative DGD) non-spontaneous, with a positive DG

87. When a reaction is exothermic and the products havemore entropy than the reactants, the reaction is

A) S must be negative.B) S must be positive.C) G must be negative.D) G must be positive.

88. Which condition is necessary for a chemical reaction tooccur spontaneously?

A) B)

C) D)

89. Which potential energy diagram indicates a reactioncan occur spontaneously?

A) ICl(g) B) CO2(g)C) H2O( ) D) Al2O3(s)

90. According to Reference Table U, which compound isspontaneously formed even though the reaction isendothermic?

A) C2H2(g) B) C2H4(g)C) HF(g) D) HI(g)

91. Which compound forms spontaneously from itselements at 1 atm and 298 K?

A) B)C) D)

92. The change in the free energy of a reaction ( G) isequal to

A) HF B) HI C) NO D) NO2

93. Based on Reference Table U, the compound whichcould form spontaneously under standard conditionsfrom its elements is

A)B)C)D)

94. Which equation correctly represents the free energychange in a chemical reaction?

Answer KeyKinetics & Equilibrium

1. C2. C3. B4. C5. C6. C7. D8. A9. C10. D11. D12. D13. D14. B15. C16. B17. C18. B19. D20. D21. A22. A23. D24. C25. D26. C27. D28. C29. B30. B31. D32. B33. B34. B35. A36. B

37. B38. B39. A40. D41. D42. B43. D44. A45. A46. D47. B48. D49. A50. D51. C52. C53. C54. A55. B56. A57. C58. C59. C60. B61. B62. D63. C64. B65. C66. D67. A68. D69. B70. B71. A72. C

73. C74. B75. C76. C77. B78. C79. C80. C81. B82. A83. A84. B85. A86. B87. A88. C89. D90. A91. C92. C93. A94. B

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1.Which event must always occur for a chemical reaction 8