Deck 10: Reaction Rates and Chemical Equilibrium

Question 1

Refrigerating perishable foods affects biochemical reactions by

A)increasing concentrations of antioxidants.
B)removing bacteria.
C)decreasing the rate of reactions affecting spoilage.
D)catalyzing the removal of harmful chemicals from the foods.
E)improving the appearance of the foods.

Answer 1

decreasing the rate of reactions affecting spoilage.

Question 2

In any chemical reaction, the rate of the reaction can be increased by

A)decreasing the temperature.
B)changing the size of the container.
C)adding water to the reaction.
D)adding product molecules to the reaction mixture.
E)increasing the concentrations of the reactants.

Answer 2

increasing the concentrations of the reactants.

Question 3

The reaction for the decomposition of PCl5 to chlorine and PCl₃ is shown below. PCl5(g) ⇌ PCl₃(g) + Cl₂(g) If the equilibrium concentrations are [PCl5] = 1.0 M, [PCl₃ ] = 0.10 M, [Cl₂ ] = 0.10 M, what is the value of the equilibrium constant?

A)1.0 × 10-2
B)1.0 × 10-4
C)10 × 10-2
D)1.0 × 102
E)2.0 × 10-2

Answer 3

1.0 × 10-2

Question 4

The rate of any chemical reaction can be determined by observing

A)the amount of product formed in a unit of time.
B)the ratio of product concentration to reactant concentration.
C)the percent composition of the final product.
D)the theoretical yield of the reaction.
E)the number of chemical bonds broken and remade.

Question 5

What is the correct form of the equilibrium constant for the reaction of hydrogen and oxygen to form water? The equation is: 2H2(g) + O2(g) ⇌ H2O(g)

A)Kc =
B)Kc =
C)Kc =
D)Kc =
E)Kc =

Question 6

The equation for the formation of ammonia from nitrogen and hydrogen is shown below. What is the form of the equilibrium constant? 3H2(g) + N2(g) ⇌ 2NH₃(g)

A)
B)
C)
D)
E)

Question 7

For the following reaction, the equilibrium concentration of NO2 is 0.38 M and equilibrium concentration of N2O₄ is 1.0M. What is the value of the equilibrium constant? 2NO2(g) ⇌ N2O₄(g)

A)0.14
B)2.6
C)6.9
D)0.38
E)1.0

Question 8

In a catalytic converter in an automobile, the reaction of carbon monoxide with oxygen produces

A)carbon dioxide.
B)carbon and more oxygen.
C)water.
D)methane.
E)nitrogen oxide.

Question 9

An equilibrium in which all the components are gases is a ________ equilibrium.

A)heterogeneous
B)liquid
C)catalytic
D)homogeneous
E)reversible

Question 10

A catalyst is

A)a reactant in a chemical reaction.
B)a product in a chemical reaction.
C)a substance that speeds up a reaction without being consumed in the reaction.
D)a substance that increases the energy of the products.
E)a substance that decreases the energy of the products.

Question 11

In the following gas phase reaction, Kc is much less than 1. At equilibrium, which of the following statements is true? COCl₂(g) ⇌ CO(g) + Cl₂(g)

A)The concentration of reactant is much greater than the concentration of products.
B)The concentration of products is much greater than the concentration of reactants.
C)The concentrations of products and reactants are approximately equal.
D)A catalyst will increase the concentration of products formed.
E)At equilibrium, the concentrations of reactants and products are equal.

Question 12

When a reaction is at equilibrium,

A)all reaction stops.
B)no more reactants are converted to products.
C)the reaction is no longer reversible.
D)the forward and reverse reactions occur at the same rate.
E)the products and reactants have the same energy content.

Question 13

In a catalyzed chemical reaction, one function of a catalyst is to

A)increase the number of successful reactant collisions.
B)decrease the concentration of reactants.
C)change the equilibrium concentrations of the products and reactants.
D)increase the energy given off during the reaction.
E)increase the temperature at which the reaction is carried out.

Question 14

In the reaction of nitrogen and hydrogen to give ammonia, all the reactants and products are

A)gases.
B)liquids.
C)solids.
D)boiling.
E)frozen.

Question 15

The activation energy of a chemical reaction is the energy that

A)must be removed from the mixture.
B)must be released from the mixture.
C)initiates the reaction.
D)activates the catalyst.
E)is the difference in the energies of the starting materials and products.

Question 16

One metal that is used as a catalyst in a catalytic converter in an automobile is

A)carbon.
B)iron.
C)copper.
D)platinum.
E)plutonium.

Question 17

The equilibrium for the reaction for the decomposition of PCl5 to chlorine and PCl₃ is 0.042. PCl5(g) ⇌ PCl₃(g)+ Cl₂(g) If the equilibrium concentrations are [PCl₃ ] = 0.010 M, [Cl₂ ] = 0.10 M, what is the value of [PCl5]?

A)0.010 M
B)0.0020 M
C)0.042 M
D)0.024 M
E)0.0010 M

Question 18

What is the correct form for the equilibrium constant expression for this reaction? H2(g) + F2(g) ⇌ 2HF(g)

A)
B)
C)
D)
E)

Question 19

A reaction that can proceed in either the forward or the reverse direction as written is called a ________ reaction.

A)reversible
B)miniscule
C)microscopic
D)solid phase
E)favored

Question 20

A chemical reaction has reached equilibrium when

A)the concentrations of reactants and products are equal.
B)all reactants have been converted to products.
C)all products have been removed from the reaction mixture.
D)the catalyst has been used up.
E)the rate of the forward reaction equals the rate of the reverse reaction.

Question 21

In the following gas phase reaction, what is the effect on the direction of the reaction if more SO₃ is added to the reaction mixture? 2SO2(g) + O2(g) ⇌ 2SO₃(g)

A)The equilibrium shifts to produce more products.
B)The position of the equilibrium remains unchanged.
C)The rate of formation of products is increased.
D)The equilibrium shifts to produce more reactants.
E)The catalyst for the reaction is used up.

Question 22

The physiological equilibrium system that keeps the temperature of the body constant is called

A)stimulation.
B)regulation.
C)metabolism.
D)homeostasis.
E)catalysis.

Question 23

The equilibrium constant for the production of carbon dioxide from carbon monoxide and oxygen is Kc = 2 × 1011. This means that the reaction mixture at equilibrium is likely to consist of

A)mostly starting materials.
B)an equal mixture of products and reactants.
C)twice as much starting material as product.
D)twice as much product as starting material.
E)mostly products.

Question 24

N2(g) + O2(g) ⇌ 2NO(g) For the reaction at equilibrium, if the volume of the container is decreased, the amount of NO present will

A)decrease.
B)increase.
C)double.
D)stay the same.
E)triple.

Question 25

2SO2(g) + O2(g) ⇌ 2SO₃(g) For the reaction at equilibrium, if O2 is added, the amount of SO2 present will

A)decrease.
B)increase.
C)stay the same.

Question 26

Which of the following equilibrium constants indicates the reaction that gives the smallest amount of product?

A)Kc = 5 × 10-10
B)Kc = 5 × 10-1
C)Kc = 5 × 100
D)Kc = 5 × 101
E)Kc = 5 × 1010

Question 27

For the following reaction, the equilibrium constant Kc is 2.0 at a certain temperature. If the concentration of both products is 0.10 M at equilibrium, what is the concentration of the starting material, NOBr? 2NOBr(g) ⇌ 2NO(g) + Br2(g)

A)5 × 10-4 M
B)2.2 × 10-4 M
C)5 × 10-2 M
D)2.2 × 10-2 M
E)2.2 M

Question 28

Treatment of carbon monoxide poisoning can be accomplished by the use of pure oxygen for breathing. This is an example of the use of ________ in a clinical setting.

A)the ideal gas law
B)Le Châtelier's principle
C)Henry's law
D)conservation of mass
E)a precipitation reaction

Question 29

In the reaction of nitrogen gas with oxygen gas to produce nitrogen oxide, what is the effect of adding more oxygen gas to the initial reaction mixture? The reaction is shown below. N2(g) + O2(g) ⇌ 2NO(g)

A)The equilibrium shifts to produce more N2.
B)The equilibrium shifts to produce more NO.
C)The equilibrium is not affected.
D)Extra catalyst is required to reach equilibrium.
E)The temperature of the reaction mixture is raised.

Question 30

For the following equilibrium reaction, which cause and effect are correctly matched? CO(g) + 2H2(g) ⇌ CH₃ OH(g) + heat

A)add heat, shift right
B)add CO, shift left
C)remove CH₃
OH, shift left
D)remove heat, no change
E)remove H2, shift left

Question 31

In the reaction of carbon dioxide with water to give carbonic acid, the only gaseous component is the carbon dioxide. What will happen to the equilibrium concentration of carbonic acid if the pressure of carbon dioxide is increased in the container?

A)The concentration of carbonic acid will increase.
B)The carbonic acid concentration will decrease.
C)The carbonic acid concentration will stay the same.
D)There will be twice as much carbonic acid as carbon dioxide.
E)There will be more water available for the reaction.

Question 32

In an exothermic reaction, heat can be considered a

A)reactant.
B)product.
C)rate.
D)catalyst.
E)determinant.

Question 33

In the following gas phase reaction, what is the effect of adding more NO2 to the starting reaction mixture? 2NO2(g) ⇌ N2O₄(g)

A)It would make the reaction more endothermic.
B)It would make the reaction more exothermic.
C)It would slow the reaction down.
D)It would decrease the final quantity of products.
E)It would increase the final quantity of products.

Question 34

The value of the equilibrium constant for the combination of nitrogen and oxygen to make NO is 2 × 10-9. What does this tell you about the concentrations of materials in the equilibrium mixture?

A)The concentration of products exceeds the concentration of reactants.
B)The concentrations of reactants and products are equal.
C)The reactants are solids.
D)The concentration of reactants exceeds the concentration of products.
E)The products are solids.

Question 35

When you open a bottle of a soft drink and leave it open, the drink eventually goes flat. This happens because the equilibrium between carbonic acid and carbon dioxide shifts to produce

A)more carbonic acid.
B)more water.
C)more oxygen.
D)more carbon dioxide.
E)more hydrogen ions.

Question 36

Carbon monoxide binds to hemoglobin 140 times more strongly than oxygen does. What does this tell you about the equilibrium constants for the two reactions of hemoglobin with carbon monoxide and oxygen?

A)The equilibrium constant for the binding of CO is greater.
B)The equilibrium constant for the binding of oxygen is greater.
C)The concentration of carbon monoxide at equilibrium is twice that of oxygen.
D)Oxygen and carbon monoxide have the same formula mass.
E)Oxygen and carbon monoxide react with hemoglobin in different fashions.

Question 37

The reaction of hemoglobin with oxygen can be written as follows. Hb + O2 ⇌ HbO₂ If the amount of oxygen available to the blood decreases significantly, what happens to the individual involved?

A)Hypoxia results.
B)Anemia results.
C)Nitrogen narcosis results.
D)Oxygen poisoning results.
E)Acclimatization results.

Question 38

PCl5 (g) ⇌ PCl₃ (g)+ Cl₂ (g) For the reaction at equilibrium, if the volume of the container is increased, the amount of PCl5 present will

A)decrease.
B)increase.
C)double.
D)stay the same.
E)triple.

Question 39

Iron metal reacts with oxygen gas to produce iron(III) oxide. What will be the effect of increasing the pressure of oxygen gas in a closed reaction vessel?

A)Less reaction will take place.
B)More iron oxide will be produced.
C)The reaction mixture will catch fire.
D)There is no effect; a catalyst is needed.
E)The rate of production of iron oxide will slow down.

Question 40

For the following reaction, the equilibrium constant Kc is 0.60 at a certain temperature. If the concentration of NO(g) and NOBr(g) are both 0.50 M,at equilibrium, what is the concentration of Br2(g)? 2NO(g) + Br2(g) ⇌ 2NOBr(g)

A)1.7 M
B)0.60 M
C)0.36 M
D)2.8 M
E)1.0 M

Question 41

The equilibrium between hemoglobin and oxyhemoglobin in the blood can be represented by the following reaction. Write the form of the equilibrium constant expression. Hb + O₂ ⇌ HbO₂

Question 42

2SO2(g) + O2(g) ⇌ 2SO₃(g) For the reaction at equilibrium, if O2 is removed, the amount of SO2 present will

A)decrease
B)increase
C)stay the same

Question 43

A catalyst for a chemical reaction affects the magnitude of the equilibrium constant.

Question 44

The rate of a chemical reaction depends on temperature.

Question 45

What is the correct form of the equilibrium constant for this reaction? 2H2O2 (g) ⇌ 2H2O (g) + O2 (g)

A)
B)
C)
D)

Question 46

The rule or principle that describes the effect of changing reaction conditions on an equilibrium is known as ________ principle.

Question 47

The equilibrium constant is the ratio of the concentrations of the reactants over the concentrations of the products.

Question 48

A catalyst lowers the activation energy of a chemical reaction.

Question 49

Write the equilibrium constant expression for the reaction of nitrogen and hydrogen to give ammonia, NH₃ .

Question 50

Activation energy is always a large amount of energy.

Question 51

One of the substances acted upon by a catalytic converter in an automobile is carbon dioxide.

Question 52

For the following reaction, the equilibrium constant Kc is 2.0 at a certain temperature. Write the equilibrium constant expression of the equilibrium constant, Kc. 2NOBr(g) ⇌ 2NO(g) + Br2(g)

A)
B)
C)
D)
E)

Question 53

For the following reaction, the equilibrium constant Kc is 2.0 at a certain temperature. Bromine can be liquefied easily and removed from the reaction vessel as it is formed. If this is done, how will it affect the equilibrium reaction? 2NOBr(g) ⇌ 2NO(g) + Br2(g)

A)More products will be made as Br2 is removed.
B)There will be a larger proportion NOBr in the vessel when equilibrium is reached.
C)Less NO will be made.
D)The pressure in the vessel will increase.
E)The equilibrium constant will change.

Question 54

At equilibrium, the concentrations of the reactants and products are always equal.

Question 55

For the following reaction, the equilibrium constant Kc is 2.0 at a certain temperature. The reaction is endothermic. What do you expect to happen to the concentration of NO if the temperature is doubled? 2NOBr(g) ⇌ 2NO(g) + Br2(g)

A)The concentration of NO will increase.
B)The concentration of NO will decrease.
C)There will be no change in [NO].
D)A catalyst will be needed to make a change in concentration.
E)The change in concentration of [NO] will depend on the size of the vessel.

Question 56

The ________ is the energy difference between reactants and products in a chemical reaction.

A)transition energy
B)activation energy
C)product energy
D)overall energy
E)heat of reaction

Question 57

The rate of a chemical reaction is not affected by the concentration of reactants.

Question 58

An equilibrium constant with a value greater than 1 means the reaction favors the ________.

Question 59

A mixture at equilibrium that contains less product than reactant has a Kc that is ________ than 1.

Question 60

3H2(g) + N2(g) ⇌ 2NH₃(g) + heat For the reaction at equilibrium, if the temperature is raised, the amount of N2 will

A)decrease.
B)increase.
C)stay the same.

Question 61

An equilibrium constant K_c = 1 × 10⁷ for a reaction indicates that the reaction favors product formation.

Question 62

The equilibrium constant for the reaction of H₂ and F₂ to form HF, the concentration of HF is raised to the second power.

Question 63

If the equilibrium constant for a reaction is 1 × 10-5, this means that the equilibrium mixture contains mostly reactants.

Question 64

The equilibrium constant for a reaction does not change with temperature.

Question 65

An example of a stress on an equilibrium is the increase of pressure in a closed system when the pressure of a reactant gas is increased from 1.0 atm to 2.0 atm.

Question 66

An equilibrium constant greater than 1 for a reaction indicates that the reaction favors formation of the products.

Question 67

An equilibrium constant K_c = 1 × 10^-3 for a reaction indicates that the reaction favors product formation.