Q: For the reaction $$2NO_2(g) \rightarrow 2NO(g) + O_2$(g)$$, which of the following correctly expresses the average rate of disappearance of $$NO_2 in $$terms of the appearance of $$O_2$$?

$$\text{Rate} = -\frac{1}{2} \frac{\Delta [NO_2$]}{\Delta t} = \frac{\Delta [O_2$]}{\Delta t}$$

Question 1

Which of the following statements best describes the difference between the differential and integrated rate laws for a chemical reaction?

Accepted Answer

The differential rate law relates the rate of reaction to the concentrations of reactants, while the integrated rate law relates the concentrations of reactants to time.

Question 2

For the reaction $$2NO_2(g) \rightarrow 2NO(g) + O_2$(g)$$, which of the following correctly expresses the average rate of disappearance of $$NO_2 in $$terms of the appearance of $$O_2$$?

Accepted Answer

$$	ext{Rate} = -\frac{1}{2} \frac{\Delta [NO_2$]}{\Delta t} = \frac{\Delta [O_2$]}{\Delta t}$$

Question 3

Which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

The color of the reactants

Question 4

A reaction is found to be first order in $$A$$ and second order in $$B. $$What is the correct rate law for this reaction?

Accepted Answer

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

Question 5

Which of the following graphs would yield a straight line for a first-order reaction?

Accepted Answer

$$\ln[A] vs$$. $$t$$

Question 6

The half-life of a first-order reaction is given by which of the following equations?

Accepted Answer

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

Question 7

If the rate constant $$k$$ for a reaction increases with temperature, which equation best describes this relationship?

Accepted Answer

$$k = Ae$$^{-E_a/RT}$$

Question 8

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Decreasing the activation energy

Question 9

Which of the following statements about reaction mechanisms is TRUE?

Accepted Answer

The slowest step in a reaction mechanism determines the overall rate law.

Question 10

For a reaction with the rate law $$	ext{Rate} = k[A]$$, which of the following is the correct integrated rate law?

Accepted Answer

$$\ln[A] = -kt + \ln[A]_0$$

Question 11

In a pseudo first-order reaction, one reactant is present in large excess. What is the practical effect of this on the rate law?

Accepted Answer

The reaction rate appears to depend only on the concentration of the limiting reactant.

Question 12

Which of the following best describes the molecularity of an elementary step involving two reactant molecules?

Accepted Answer

Bimolecular

Question 13

A student is studying the decomposition of $$N_2O_5$$ and finds that plotting $$1/[N_2O_5]$$ versus time gives a straight line. What is the order of the reaction?

Accepted Answer

Second order

Question 14

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

Accepted Answer

Intermediates are formed and consumed during the reaction.

Question 15

Consider the reaction $$A \rightarrow B$$ with a zero-order rate law. If the initial concentration of $$A is $$doubled, what happens to the rate?

Accepted Answer

The rate remains the same.

Question 16

Which of the following is a real-world example of a heterogeneous catalyst?

Accepted Answer

Platinum in a car's catalytic converter converting CO to CO$$_2$$

Question 17

Given the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$, what does E_a$ represent?

Accepted Answer

The activation energy required for the reaction to occur

Question 18

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

Accepted Answer

It increases the number of molecules with energy greater than the activation energy.

Question 19

A reaction has a rate law $$	ext{Rate} = k[NO_2$][F_2$]. If $$the concentration of $$NO_2 is $$doubled and $$F_2 is $$kept constant, by what factor does the rate increase?

Accepted Answer

2

Question 20

Which of the following statements about catalysts is FALSE?

Accepted Answer

Catalysts increase the equilibrium constant of a reaction.

Chemical Kinetics: Rates, Mechanisms, and Catalysis

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