Ch 14

Question 1

Nitrogen dioxide reacts with carbon monoxide to produce nitrogen monoxide and carbon dioxide.
NO2(g) + CO(g) → NO(g) + CO2(g)
A proposed mechanism for this reaction is
2 NO2(g) NO3(g) + NO(g) (fast, equilibrium)
NO3(g) + CO(g) → NO2(g) + CO2(g) (slow)
What is a rate law that is consistent with the proposed mechanism?

rate = k[NO2]2[CO] [NO]–1
rate = k[NO2]2[CO]
rate = k[NO2][CO]
rate = k[NO3][CO]
rate = k[NO2]2

Answer 1

a.

Question 2

For the reaction A + 2B → C, the rate law is
.
What are the units of the rate constant where time is measured in seconds?

Answer 2

b.

Question 3

The reaction kinetics for a certain reaction are studied over several temperatures. Which of the following is/are not effected by a change in reaction temperature?
the reaction rate
the rate constant, k
the energy of activation, Ea
a and b
a, b, and c

Answer 3

c.

Question 4

In general, as temperature increases, the rate of a chemical reaction
decreases due to fewer collisions with proper molecular orientation.
increases for exothermic reactions, but decreases for endothermic reactions.
increases due to a greater number of effective collisions.
remains unchanged.
decreases due to an increase in the activation energy.

Answer 4

c.

Question 5

For the overall reaction
2A + B → C
which of the following mechanisms is/are consistent with a rate equation of rate = k[A]2[B]?

A + B I (fast)
I + A → C (slow)
A + B → I (slow)
I + A → C (fast)
2A → I (slow)
B + I → C (fast)
2A I (fast)
I + B → C (slow)
Answers a and d are both correct.

Answer 5

e.

Question 6

The _____ of an elementary step is defined as the number of reactant molecules that come together in a reaction.

Answer 6

molecularity

Question 7

Which of the following is not a correct representation of the integrated rate expression for a decomposition first-order reaction?

Answer 7

e.

Question 8

Which of the following statements is correct for the first-order reaction: A → 2B?
The concentration of A decreases linearly with respect to time.
The concentration of A is constant with respect to time.
The natural logarithm of the concentration of A decreases linearly with respect to time.
The rate of reaction is constant with respect to time.
The rate constant, k, of the reaction decreases linearly with respect to time.

Answer 8

c.

Question 9

The Arrhenius equation, expresses the dependence of the rate constant on the reaction temperature. The slope of a plot of ln(k) versus 1/T is equal to

Answer 9

e.

Question 10

In a reaction coordinate diagram, reacting molecules are most unstable ______.
at their initial position
when they are about to collide
right after they collide
at the transition state

Answer 10

d.

Question 11

Which of the following statements is true of the Arrhenius equation?
Group of answer choices

The factor always has a value more than 1.

Ea represents the fraction of molecules having the minimum energy required for a reaction.

It can be used to calculate Ea from the temperature dependence of the rate constant.

It can be used to calculate the rate constant if is known.

The factor always has a value more than 10.

Answer 11

c.

Question 12

The pre-exponential, A, in the Arrhenius equation is called the ________ factor.

Answer 12

frequency

Question 13

Molecules must overcome a barrier called the activation energy if they are to react. The highest energy point reached during the progress of a reaction is called the ____.
Group of answer choices

rate determining step

transition state

half-life

elementary step

intermediate state

Answer 13

b.

Question 14

Which of the following is the effect of adding a catalyst to a reaction?
Group of answer choices

Increase in the number of collisions between reactants

Lowering of the activation energy of a reaction

Increase in the equilibrium constant of a reaction

Decrease in the yield of the products

Increase in the enthalpy change of a reaction

Answer 14

b.

Question 15

Which of the following units are consistent with the units of the reaction rate in a first order reaction?

Answer 15

a.

Question 16

Which of the following steps must occur for an enzyme to catalyze a reaction?
Group of answer choices

The reactant, often called the substrate, must bind to the enzyme.

The chemical reaction must be halted.

The products of the reaction must attach to the enzyme.

The quantity of the enzymes in the reaction should keep increasing.

The reactant must bind to the product rather than the enzyme.

Answer 16

a.

Question 17

A student analyzed a first-order reaction and obtained the graph below. Unfortunately, the student forgot to label the axes. What are the correct labels for the x and y axes?

x axis = time, y axis = ln[A]

x axis = ln[time], y axis = [A]

x axis = ln[time], y axis = [A]

x axis = time, y axis = 1/[A]

x axis = 1/time, y axis = 1/[A]

Answer 17

a.

Question 18

For the zero-order reaction A → B + C, a graph of _____ versus time will generate a straight line.

Answer 18

a.

Question 19

A catalyst ____.
Group of answer choices

is used up in a chemical reaction

changes the potential energy change of the reaction

is always a solid

does not influence the reaction in any way

changes the activation energy of the reaction

Answer 19

e.

Question 20

Circle the catalyst in the following mechanism.

Question 21

For the overall reaction A + 2B → C, which of the following mechanisms yields the correct overall chemical equation and is consistent with the rate equation below?

A + B I (fast)
I + A → C (slow)
A + B → I (slow)
I + B → C (fast)
2B → I (slow)
A + I → C (fast)
2B I (fast)
I + A → C (slow)
A + 2B I (fast)
I + B → C + B (slow)

Answer 21

b.

Question 22

Consider the exothermic combustion of coal. Which of the following could increase the rate of reaction?
Group of answer choices

Using smaller pieces of coal

Increasing the concentration of oxygen

Lowering the temperature

Both a and b are correct.

None of these

Answer 22

d.

Question 23

If a reaction is second-order with respect to a particular reactant, when the concentration of that reactant is increased by a factor of 4, the reaction rate will _____.
Group of answer choices

increase by a factor of 16.

remain constant.

decrease by a factor of .

increase by a factor of 64.

decrease by a factor of .

Answer 23

a.

Question 24

The elementary steps for the catalyzed decomposition of dinitrogen monoxide are shown below.
N2O(g) + NO(g) → N2(g) + NO2(g)
NO2(g) → NO(g) + 1/2 O2(g)
Which of the following statements is/are CORRECT?
1. The overall balanced reaction is N2O(g) → N2(g) + 1/2 O2(g).
2. NO2(g) is a catalyst for the reaction.
3. NO(g) is a reaction intermediate.
Group of answer choices

1 only

2 only

3 only

1 and 3

1, 2, and 3

Answer 24

a.

Question 25

What is the name given to a substance that increases the rate of a chemical reaction but is not itself consumed? catalyst reactant intermediate enthalpy rate constant

Answer 25

a.

Question 26

According to collision theory, which condition(s) must be met in order for molecules to react? 1. The reacting molecules must collide with sufficient energy to initiate the process of breaking and forming bonds. 2. A catalyst must be in contact with the reacting molecules for a reaction to occur. 3. The reacting molecules must collide with an orientation that can lead to rearrangement of the atoms. Group of answer choices 1 only 2 only 3 only 1 and 2 1 and 3

Answer 26

e.

Question 27

A suggested mechanism for the decomposition of ozone is as follows: O3 O2 + O fast equilibrium O + O3 2O2 slow step What is the rate law predicted by this mechanism?

Answer 27

c.

Question 28

Which statement concerning relative rates of reaction is correct for the chemical equation given below? 2 CH3OH(g) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) Group of answer choices The rate of disappearance of CH3OH is equal to the rate of disappearance of O2. The rate of disappearance of CH3OH is two times the rate of appearance of H2O. The rate of disappearance of CH3OH is half the rate of appearance of CO2. The rate of appearance of H2O is two times the rate of appearance of CO2. The rate of appearance of H2O is four times the rate of disappearance of CH3OH.

Answer 28

d.

Question 29

Radioactive isotopes decay by ________-order kinetics.

Answer 29

first

Question 30

Termolecular elementary steps are rare. Why?

Answer 30

because it has three reactants

Question 31

How are the exponents in a rate law determined? Group of answer choices They are equal to the inverse of the coefficients in the overall balanced chemical equation. They are determined by experimentation. They are equal to the coefficients in the overall balanced chemical equation. They are equal to the reactant concentrations. They are equal to the ln(2) divided by the rate constant.

Answer 31

not a. or d.

Question 32

If a catalyst is present in a different phase from the reactants and products, it is referred to as a(n) ________ catalyst.

Answer 32

maybe enzyme

Question 33

For the hypothetical reaction aA → products, the experimental data showed the following behavior (below). What is the reaction order with respect to reactant A?

Answer 33

b.

Question 34

For the reaction A → B + C, which of the following equations corresponds to the integrated expression for a second-order decomposition reaction?

Answer 34

e.

Question 35

The Arrhenius equation, , relates the rate constant of reaction and temperature. A plot of ____ versus 1/T will yield a straight line with a slope of –Ea/R.

Answer 35

c.

Question 36

Which of the following is/are expected to affect the rate of a chemical reaction? 1. Addition of a catalyst. 2. Decreasing the reactant concentrations. 3. Increasing the reactant volumes but leaving the concentrations the same. Group of answer choices 1 only 2 only 3 only 1 and 2 1, 2, and 3

Answer 36

d.

Question 37

Which of the given relationships correctly compares the rates of the reactants and products for the reaction below?

Answer 37

not b. or d.

Question 38

Consider the following proposed mechanism. If this mechanism for the overall reaction were correct, and if k1 were much less than k2, then the observed rate law would be 2A C + I I + B C + D Group of answer choices rate = k1[A] rate = k2[I][B] c. rate = k1[A]2 rate = k1[A]2 − k2[C][D] rate = k1k2[A]2[I][B]

Answer 38

c.

Question 39

How many mechanistic steps are depicted by in this potential energy diagram? one step two steps three steps four steps five steps

Answer 39

not b.