Question 1

Which of the following statements best describes the rate law for the reaction: $$A + 2B \rightarrow C if $$the reaction is first order in $$A$$ and second order in $$B$$?

Accepted Answer

$$	ext{Rate} = k[A][B]^2$$

Question 2

A reaction is found to be zero order in $$A. $$Which of the following graphs would be linear?

Accepted Answer

$$[A] vs$$. $$t$$

Question 3

For a first-order reaction, what is the relationship between the half-life $$t_{1/2}$$ and the rate constant $$k$$?

Accepted Answer

$$t_{1/2} = \dfrac{0.693}{k}$$

Question 4

Which of the following is true for a second-order reaction with respect to $$A$$?

Accepted Answer

A plot of $$1/[A] vs$$. $$t is $$linear.

Question 5

The decomposition of $$NO_2 is $$found to be second order. If $$[NO_2$] is $$doubled, what happens to the rate?

Accepted Answer

The rate quadruples.

Question 6

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the fraction of molecules with energy greater than $$E_a.$$

Question 7

According to the collision model, which of the following is NOT required for a successful reaction?

Accepted Answer

Molecules must be in the gas phase.

Question 8

The Arrhenius equation is $$k = Ae$$^{-E_a/RT}$$. What does a plot of $$\ln k$$ vs. 1/T$ yield?

Accepted Answer

A straight line with slope $$-E_a/R$$

Question 9

Which of the following statements about reaction mechanisms is correct?

Accepted Answer

The slowest step in the mechanism determines the rate law.

Question 10

A catalyst increases the rate of a reaction by:

Accepted Answer

Providing an alternative pathway with lower activation energy.

Question 11

Which of the following is a characteristic of a homogeneous catalyst?

Accepted Answer

It is in the same phase as the reactants.

Question 12

For the reaction $$NO_2 + CO$$ ightarrow NO + $$CO_2$$, the experimentally determined rate law is $$	ext{Rate} = k[NO_2$]^2. $$What does this suggest about the mechanism?

Accepted Answer

The reaction is second order overall.

Question 13

Which of the following is true about intermediates in a reaction mechanism?

Accepted Answer

They are produced in one step and consumed in a later step.

Question 14

Which of the following best describes the half-life of a second-order reaction?

Accepted Answer

$$t_{1/2} = \dfrac{1}{k[A]_0}$$

Question 15

Which of the following is a requirement for a plausible reaction mechanism?

Accepted Answer

The sum of the elementary steps must give the overall reaction.

Question 16

Which of the following is true for a termolecular elementary step?

Accepted Answer

It involves the simultaneous collision of three molecules.

Question 17

Which of the following best describes the effect of a catalyst on a reaction coordinate diagram?

Accepted Answer

It lowers the activation energy.

Question 18

Which of the following is true about enzymes?

Accepted Answer

They are biological catalysts.

Question 19

A reaction has a rate law $$	ext{Rate} = k[A][B]. If$$ $$[A] is $$doubled and $$[B] is $$tripled, by what factor does the rate increase?

Accepted Answer

6

Question 20

Which of the following is NOT a factor that affects the rate constant $$k$$?

Accepted Answer

Concentration of reactants

Chapter 14: Chemical Kinetics III – Rate Laws, Mechanisms, and Catalysis

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