Question 1

Which of the following best describes the rate law for the reaction: $$2NO_2(g) \rightarrow 2NO(g) + O_2$(g)$$, if the reaction is found experimentally to be second order in $$NO_2$$?

Accepted Answer

$$	ext{Rate} = k[NO_2$]^2$$

Question 2

For the reaction $$2O_3(g) \rightarrow 3O_2(g)$$, which of the following correctly relates the rate of disappearance of $$O_3 to $$the rate of appearance of $$O_2$$?

Accepted Answer

$$\frac{1}{2}\frac{\Delta [O_3$]}{\Delta t} = \frac{1}{3}\frac{\Delta [O_2$]}{\Delta t}$$

Question 3

Which of the following is true regarding the units of the rate constant $$k$$ for a second-order reaction?

Accepted Answer

$$M^{-1}$$ $$s^{-1}$$

Question 4

A reaction is found to be first order in $$A$$ and first order in $$B. If $$the concentration of $$A is $$doubled and $$B is $$tripled, by what factor does the rate increase?

Accepted Answer

6

Question 5

Which integrated rate law corresponds to a first-order reaction?

Accepted Answer

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

Question 6

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

Accepted Answer

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

Question 7

Which of the following statements about the collision model is correct?

Accepted Answer

Molecules must collide with sufficient energy and proper orientation to react.

Question 8

Which of the following best describes the effect of temperature on the rate constant $$k$$?

Accepted Answer

As temperature increases, $$k$$ increases because more molecules have energy greater than $$E_a.$$

Question 9

The Arrhenius equation is $$k = Ae$$^{-E_a/RT}$$. Which plot would yield a straight line to determine E_a$ graphically?

Accepted Answer

$$\ln k vs$$ $$1/T$$

Question 10

A reaction mechanism consists of the following steps:
1) $$A + B \rightarrow C ($$slow)
2) $$C + D \rightarrow E ($$fast)
What is the rate law for the overall reaction?

Accepted Answer

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

Question 11

Which of the following is NOT a requirement for a plausible reaction mechanism?

Accepted Answer

The rate-determining step must be the fastest step.

Question 12

Which of the following statements about intermediates is correct?

Accepted Answer

Intermediates are produced in one step and consumed in a subsequent step.

Question 13

For a zero-order reaction, which of the following is true?

Accepted Answer

The rate is independent of the concentration of reactant.

Question 14

Which of the following best describes a termolecular elementary step?

Accepted Answer

It involves the simultaneous collision of three molecules.

Question 15

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Lowering the activation energy ($$E_a) of $$the reaction.

Question 16

If a reaction is first order in $$A$$ and zero order in $$B$$, what happens to the rate if $$[A] is $$doubled and $$[B] is $$tripled?

Accepted Answer

The rate doubles.

Question 17

Which of the following is the correct expression for the half-life of a second-order reaction?

Accepted Answer

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

Question 18

Which of the following is true about the transition state (activated complex) in a reaction?

Accepted Answer

It is the highest energy point along the reaction pathway.

Question 19

In the Arrhenius equation, what does the parameter $$A$$ represent?

Accepted Answer

The frequency factor, related to the frequency and orientation of collisions.

Chapter 14: Chemical Kinetics II – Reaction Rates, Rate Laws, and Mechanisms

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