Question 1

A lizard becomes lethargic when its body temperature drops. Which principle of chemical kinetics best explains this phenomenon?

Accepted Answer

The rate of chemical reactions decreases as temperature decreases, slowing down metabolic processes.

Question 2

For the reaction $$2	ext{NO}_2(g) ightarrow 2	ext{NO}(g) + 	ext{O}_2(g)$$, the rate law is found to be $$	ext{Rate} = k[	ext{NO}_2]^2. If $$the initial concentration of $$	ext{NO}_2 is $$doubled, what happens to the reaction rate?

Accepted Answer

The rate quadruples.

Question 3

Which of the following best describes the instantaneous rate of a reaction?

Accepted Answer

It is the rate measured at a specific moment, determined by the slope of the tangent to the concentration vs. time curve.

Question 4

A reaction is found to be first order in A and second order in B. What is the overall order of the reaction?

Accepted Answer

Third order

Question 5

Which experimental technique would be most appropriate for monitoring the progress of a reaction that produces a colored product?

Accepted Answer

Spectrophotometry

Question 6

For a first-order reaction, which of the following plots yields a straight line?

Accepted Answer

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

Question 7

The half-life of a first-order reaction is 20 minutes. If the initial concentration is 0.80 M, what will the concentration be after 40 minutes?

Accepted Answer

0.20 M

Question 8

Which statement about the Arrhenius equation is correct?

Accepted Answer

The rate constant $$k$$ decreases as activation energy increases, all else being equal.

Question 9

A reaction has a rate law $$	ext{Rate} = k[A][B]^2. If$$ $$[A] is $$doubled and $$[B] is $$tripled, by what factor does the rate increase?

Accepted Answer

18

Question 10

Which of the following best explains why a catalyst increases the rate of a chemical reaction?

Accepted Answer

It provides an alternative pathway with a lower activation energy.

Question 11

Which of the following statements about reaction mechanisms is true?

Accepted Answer

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

Question 12

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

Accepted Answer

The rate is independent of the concentration of the reactant.

Question 13

Which of the following is NOT a requirement for a collision to be effective in collision theory?

Accepted Answer

The molecules must be in the gas phase.

Question 14

Which of the following statements about the half-life of a reaction is correct?

Accepted Answer

The half-life of a first-order reaction is independent of the initial concentration.

Question 15

Which of the following best describes a reaction intermediate?

Accepted Answer

A substance that is formed in one step of a mechanism and consumed in a later step.

Question 16

A reaction is found to have a rate law $$	ext{Rate} = k[A]^0. $$What will happen to the rate if $$[A] is $$tripled?

Accepted Answer

The rate will remain the same.

Question 17

Which of the following is a correct statement about the effect of temperature on reaction rate?

Accepted Answer

Increasing temperature increases the fraction of molecules with enough energy to overcome the activation barrier.

Question 18

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

Accepted Answer

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

Question 19

Which of the following best describes the role of an enzyme in a biological reaction?

Accepted Answer

It provides a specific orientation for the substrate, lowering the activation energy.

Question 20

A reaction has a rate law $$	ext{Rate} = k[A]^2. If $$the initial rate is $$0.0100\ 	ext{M/s} at$$ $$[A] = 0.100\ 	ext{M}$$, what is the rate at $$[A] = 0.500\ 	ext{M}$$?

Accepted Answer

$$0.0500\ 	ext{M/s}$$

Chemical Kinetics: Study Guide for General Chemistry

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