Deck 9: Chemical Reactions

Question 1

Which of the following statements concerning redox reactions is incorrect?

A) The oxidizing agent is the substance reduced.
B) The reducing agent is the substance oxidized.
C) The oxidizing agent loses electrons.
D) The substance oxidized loses electrons.

Answer 1

The oxidizing agent loses electrons.

Question 2

The minimum combined kinetic energy reactant particles must possess in order for their collision to result in a reaction is called the

A) dissociation energy
B) collision energy
C) activation energy
D) orientation energy

Answer 2

activation energy

Question 3

Combustion reactions are characterized by

A) oxygen always being one of the reactants
B) water always being one of the products
C) carbon dioxide always being one of the products
D) both reactants always being elements

Answer 3

oxygen always being one of the reactants

Question 4

Which of the following is the correct equilibrium constant expression for the reaction

A)
B)
C)
D)

Question 5

The proper assignment of oxidation numbers to the elements in the compound LiAsO₃ would be

A) +1 for Li, +5 for As and -2 for O
B) +1 for Li, +5 for As and -6 for O
C) +1 for Li, +1 for As and -2 for O
D) +2 for Li, +4 for As and -6 for O

Question 6

Most reactions are carried out in liquid solution or in the gaseous phase because in such situations

A) Activation energies are higher.
B) It is easier for reactants to come in contact with each other.
C) Kinetic energies of reactants are lower.
D) Products are less apt to decompose.

Question 7

According to Le Chatelier's principle, which of the following changes will shift the position of the equilibrium to the left for the reaction

A) double the concentration of N₂
B) decrease the concentration of NH₃
C) increase the concentration of H₂
D) triple the temperature

Question 8

The proper assignment of oxidation numbers to the elements in the polyatomic ion SO₃^2- would be

A) +6 for S and -6 for O
B) +6 for S and -2 for O
C) +4 for S and -6 for O
D) +4 for S and -2 for O

Question 9

Whether a reaction is exothermic or endothermic is determined by

A) the activation energy
B) the physical state of the reactants
C) how reactant and product potential energies compare
D) whether a catalyst is present

Question 10

Which substance functions as a reducing agent in the following redox reaction? CH₄ + 2 O₂ $\rightarrow$ CO₂ + 2H₂O

A) CH₄
B) O₂
C) CO₂
D) H₂O

Question 11

Catalysts are correctly characterized by each of the following statements except one. The exception is:

A) They can be either solids, liquids or gases.
B) They lower the activation energy for a reaction.
C) They do not actively participate in a reaction.
D) They are not consumed in a reaction.

Question 12

What is the change in oxidation number for cobalt in the redox reaction 2Co₂O₃ + 3C $\rightarrow$ 4Co + 3CO₂

A) +4 to -4
B) +2 to 0
C) +3 to +4
D) +3 to 0

Question 13

CO₂ and H₂ are allowed to react until an equilibrium is established as follows: What will be the effect on the equilibrium of removing CO from the equilibrium mixture?

A) The equilibrium will favor the reactants side.
B) H₂ concentration will double
C) CO and CO₂ concentrations will double
D) H₂ concentration will decrease and H₂O concentration will increase

Question 14

Which of the following general reaction types is characterized by there being a single reactant?

A) combination
B) decomposition
C) displacement
D) exchange

Question 15

For a system at chemical equilibrium:

A) Forward and reverse reaction rates are equal.
B) Forward and reverse reaction rates are zero.
C) Reactant and product concentrations are equal.
D) Reactant and product concentrations are zero.

Question 16

Which of the following changes is most likely to decrease reaction rate for the chemical reaction 2CO + O₂ $\rightarrow$ 2CO₂?

A) adding twice as much O₂ to the reaction mixture
B) tripling the temperature of the reaction mixture
C) adding a catalyst to the reaction mixture
D) removing some CO from the reaction mixture

Question 17

Which of the following reactions is a nonredox decomposition reaction?

A) 2CuO $\rightarrow$ 2Cu + O₂
B) 2KClO₃ $\rightarrow$ 2KCl + 3 O₂
C) CaCO₃ $\rightarrow$ CaO + CO₂
D) SO₂ + H₂O $\rightarrow$ H₂SO₃

Question 18

Which element is oxidized in the following redox reaction? 2H₂S + O₂ $\rightarrow$ 2H₂O + S

A) sulfur in H₂S
B) hydrogen in H₂S
C) oxygen in O₂
D) oxygen in H₂O

Question 19

In the redox reaction 2MnBr₃ + SnBr₂ $\rightarrow$ 2MnBr₂ + SnBr₄

A) SnBr₂ is the oxidizing agent
B) MnBr₃ is the substance oxidized
C) Sn undergoes an oxidation number change of two units
D) Mn undergoes an oxidation number change of six units

Question 20

Le Chatelier's principle states that:

A) Only exothermic reactions can reach chemical equilibrium.
B) Only reactions in which a catalyst is present can reach chemical equilibrium.
C) If a chemical equilibrium is disturbed, the system will try and reestablish equilibrium.
D) If a chemical equilibrium is disturbed, the temperature of the system will always decrease.

Question 21

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) The only information needed to write an equilibrium constant expression is a balanced chemical equation with physical state information for the reaction of concern.
(2) The oxidation number of sulfur is the same in the species H₂SO₄ and SO₄^2-.
(3) Increasing the concentration of a reactant makes collisions between the reactant and other reactants less likely because of "more crowded conditions."

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 22

Chemical equilibrium is reached in a system when

A) complete conversion of reactants to products has occurred
B) reactant and product concentrations are equal
C) reactants are being consumed at the same rate they are being produced
D) more than one correct response
E) no correct response

Question 23

CO₂ and H₂ are allowed to react until equilibrium is established as follows: Which of the following changes will cause the equilibrium position to shift to the right?

A) increase in the concentration of H₂
B) decrease in the concentration of CO
C) decrease in the concentration of CO₂
D) more than one correct response
E) no correct response

Question 24

For which of the following equilibrium systems will the equilibrium position shift to the left when a stress of increased pressure (from a volume decrease) is applied?

A)
B)
C)
D) more than one correct response
E) no correct response

Question 25

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
(1) A chemical system reaches equilibrium at the instant when the rate of formation of products becomes zero.
(2) One reactant and two or more products is a general characteristic of decomposition reactions.
(3) Catalysts increase reaction rate by providing an alternate reaction pathway with a higher activation energy.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 26

Which of the following statements about activation energy is correct?

A) It is the same for all reactions.
B) It is low for reactions that take place rapidly.
C) It is the maximum energy a reacting molecule may possess.
D) More than one correct response.
E) No correct response.

Question 27

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) Oxidation and reduction are complementary processes that always occur together.
(2) For a system at chemical equilibrium, decreasing the concentration of a reactant will always shift the equilibrium to the right.
(3) The reactants in a combination reaction must be elements.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 28

In the redox reaction 4Fe + 3 O₂ + 12HCl $\rightarrow$ 4FeCl₃ + 6H₂O

A) HCl is the reducing agent.
B) O₂ is the substance oxidized.
C) Fe undergoes an oxidation number decrease of three units per atom.
D) More than one correct response.
E) No correct response.

Question 29

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
(1) All chemical systems will reach equilibrium if enough time elapses.
(2) A substance that functions as a reducing agent is, itself, oxidized.
(3) In a slow reaction, the activation energy is far greater than the average energy content of the reacting particles.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 30

Which of the following statements concerning types of reactions is correct?

A) The reactant in a decomposition reaction must be a compound.
B) The reactants in a combination reaction must be elements.
C) The reactants in a displacement reaction could be two compounds.
D) More than one correct response.
E) No correct response.

Question 31

In which of the following compounds does Cl have an oxidation number of +5?

A) HClO
B) KClO₂
C) Ca(ClO₃)₂
D) more than one correct response
E) no correct response

Question 32

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) The collision between two reactant molecules does not always result in the formation of reaction products.
(2) The substance oxidized in a reaction may be either a reactant or a product.
(3) At chemical equilibrium, the concentrations of reactants and products cease to change.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 33

In a redox reaction, the oxidizing agent is the substance

A) that is oxidized
B) that loses electrons
C) that contains an element that undergoes a decrease in oxidation number
D) more than one correct response
E) no correct response

Question 34

Which of the following reactions is a non-redox reaction?

A) CaCO₃ $\rightarrow$ CaO + CO₂
B) 2KClO₃ $\rightarrow$ 2KCl + 3 O₂
C) SO₃ + H₂O $\rightarrow$ H₂SO₄
D) more than one correct response
E) no correct response

Question 35

According to Le Chatelier's principle, which of the following effects will occur if NH₃ is removed from an equilibrium mixture governed by the equation:

A) Concentration of N₂ will increase.
B) Heat will be generated.
C) Concentration of H₂ will decrease.
D) More than one correct response.
E) No correct response.

Question 36

For a collision between molecules to result in reaction, the molecules must possess a certain minimum energy and

A) exchange electrons
B) interact with a catalyst for at least one second
C) have a favorable orientation relative to each other when they collide
D) more than one correct response
E) no correct response

Question 37

In writing an equilibrium constant expression, which of the following is incorrect?

A) Concentrations are always expressed in molarities.
B) Product concentrations are always placed in the numerator of the expression.
C) Concentrations of pure solids and pure liquids are always placed in the denominator of the expression.
D) More than one correct response.
E) No correct response.

Question 38

Which of the following statements concerning oxidation and reduction is correct?

A) They cannot occur independently of each other.
B) They accompany all chemical changes.
C) They describe, respectively, the gain and loss of electrons.
D) More than one correct response.
E) No correct response.

Question 39

Increasing the temperature at which a chemical reaction occurs

A) will lower the activation energy
B) causes more reactant collisions to take place in a given time
C) increases disorder in the system, thus decreasing the reaction rate
D) more than one correct response
E) no correct response

Question 40

In which of the following sequences of sulfur-containing ions are the ions arranged in order of decreasing oxidation number for S?

A) SO₃^2-, SO₄^2-, S^2-
B) SO₄^2-, S₂O₃^2-, S^2-
C) S₂O₃^2-, SO₃^2-, SO₄^2-
D) more than one correct response
E) no correct response

Question 41

For the indicated element, select the correct oxidation number from the response list: oxidation number of C in KHCO₃⁺.

A) +2
B) +3
C) +4
D) +6

Question 42

For the indicated element, select the correct oxidation number from the response list: oxidation number of Mn in Mn³⁺.

A) +2
B) +3
C) +4
D) +6

Question 43

For the indicated element, select the correct oxidation number from the response list: oxidation number of Cr in Cr₂O₇^2-+.

A) +2
B) +3
C) +4
D) +6

Question 44

Consider the following redox equation: SO₂ + NO₂ $\rightarrow$ SO₃ + NO, choose an appropriate chemical formula from the list that identifies the reducing agent.

A) SO₂
B) SO₃
C) NO
D) NO₂

Question 45

Consider the following redox equation: SO₂ + NO₂ $\rightarrow$ SO₃ + NO, choose an appropriate chemical formula from the list that identifies the substance reduced.

A) SO₂
B) SO₃
C) NO
D) NO₂

Question 46

For the indicated element, select the correct oxidation number from the response list: oxidation number of Fe in Fe₂O₃⁺.

A) +2
B) +3
C) +4
D) +6

Question 47

Assign the following reaction to one of the reaction classifications given in the response list: 4PH₃ + Ni(CO)₄ $\rightarrow$ 4CO + Ni(PH₃)₄

A) decomposition
B) combination
C) displacement
D) exchange

Question 48

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) Decomposition reactions and addition reactions are two terms that describe the same type of reaction.
(2) Orientation relative to one another, at the moment of collision, is always a factor in determining whether a collision is effective.
(3) An increase in temperature will always cause an endothermic reaction at equilibrium to shift in the direction that produces more products.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 49

Assign the following reaction to one of the reaction classifications given in the response list: 2NO₂ + H₂O₂ $\rightarrow$ 2HNO₃

A) decomposition
B) combination
C) displacement
D) exchange

Question 50

Consider the following redox equation: SO₂ + NO₂ $\rightarrow$ SO₃ + NO, choose an appropriate chemical formula from the list that identifies the substance that loses electrons.

A) SO₂
B) SO₃
C) NO
D) NO₂

Question 51

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) The square brackets associated with a general equilibrium constant expression mean that concentrations must be expressed in terms of molarity.
(2) Pressure changes affect all chemical systems at equilibrium in which gaseous reactants or products are present.
(3) In the compound KMnO₄, the oxidation number of Mn is +3.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 52

For the indicated element, select the correct oxidation number from the response list: oxidation number of S in H₂SO₄⁺.

A) +2
B) +3
C) +4
D) +6

Question 53

Consider the following redox equation: SO₂ + NO₂ $\rightarrow$ SO₃ + NO, choose an appropriate chemical formula from the list that identifies the oxidizing agent.

A) SO₂
B) SO₃
C) NO
D) NO₂

Question 54

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) Of the known atmospheric greenhouse gases, CO₂ is both the most abundant and also the most efficient at preventing heat loss from the Earth.
(2) Ozone is a form of oxygen in which there are three atoms per molecule.
(3) A decrease in body temperature slows down the rate of chemical reactions.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 55

Consider the following redox equation: SO₂ + NO₂ $\rightarrow$ SO₃ + NO, choose an appropriate chemical formula from the list that identifies the substance oxidized.

A) SO₂
B) SO₃
C) NO
D) NO₂

Question 56

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) Electron loss is always associated with an increase in oxidation number.
(2) An exothermic reaction occurs when the energy required to break bonds in reactants is less than the energy released by bond formation in the products.
(3) The concentrations of pure liquids and pure solids are never included in an equilibrium constant expression because such concentrations never change.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 57

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices: (1) When reactants are in the solid state, reaction rate increases as temperature increases and decreases as state of subdivision increases.
(2) An oxidizing agent causes oxidation by providing electrons for the other reactant to accept.
(3) The numerical value of an equilibrium constant must always be greater than one.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 58

Assign the following reaction to one of the reaction classifications given in the response list: Mg + 2HCl $\rightarrow$ MgCl₂ + H₂

A) decomposition
B) combination
C) displacement
D) exchange

Question 59

Assign the following reaction to one of the reaction classifications given in the response list: KCN + HCl $\rightarrow$ HCN + KCl

A) decomposition
B) combination
C) displacement
D) exchange

Question 60

Assign the following reaction to one of the reaction classifications given in the response list: K₂CO₃ $\rightarrow$ K₂O + CO₂

A) decomposition
B) combination
C) displacement
D) exchange

Question 61

Consider the following equilibrim: Determine the effect on the position of equilibrium when a catalyst is added.

A) shifts to the right
B) shifts to the left
C) does not shift
D) shifts to both the left and the right

Question 62

Consider the following equilibrim: Determine the effect on the position of equilibrium when the temperature is decreased.

A) shifts to the right
B) shifts to the left
C) does not shift
D) shifts to both the left and the right

Question 63

For the following general reaction equation, choose the correct form of the equilibrium constant expression from the response list:

A)
B)
C)
D)

Question 64

Consider the following equilibrim: Determine the effect on the position of equilibrium when the volume of the container is increased (pressure decrease).

A) shifts to the right
B) shifts to the left
C) does not shift
D) shifts to both the left and the right

Question 65

Consider the following equilibrim: Determine the effect on the position of equilibrium when some H₂ is added.

A) shifts to the right
B) shifts to the left
C) does not shift
D) shifts to both the left and the right

Question 66

Consider the following equilibrim: Determine the effect on the position of equilibrium when some CO₂ is removed.

A) shifts to the right
B) shifts to the left
C) does not shift
D) shifts to both the left and the right