Q: For the reaction $$2\text{O}_3 (g) \rightarrow 3\text{O}_2 (g)$$, what is the correct expression for the average rate in terms of the change in $$[\text{O}_3]$$?

$$\text{Rate} = -\frac{1}{2}\frac{\Delta [\text{O}_3]}{\Delta t}$$

Q: The decomposition of $$\text{NO}_2 is $$second order with respect to $$\text{NO}_2. $$Which integrated rate law should be used to determine $$[\text{NO}_2] at $$any time $$t$$?

$$\frac{1}{[\text{NO}_2]_t} = kt + \frac{1}{[\text{NO}_2]_0}$$

Question 1

Which of the following best describes the concept of chemical kinetics?

Accepted Answer

The study of the speeds (rates) of chemical reactions and the factors that affect them.

Question 2

A reaction is monitored by measuring the concentration of a reactant over time. The data shows that the concentration decreases linearly with time. What is the order of the reaction with respect to this reactant?

Accepted Answer

Zero order

Question 3

For the reaction $$2	ext{O}_3 (g) ightarrow 3	ext{O}_2 (g)$$, what is the correct expression for the average rate in terms of the change in $$[	ext{O}_3]$$?

Accepted Answer

$$	ext{Rate} = -\frac{1}{2}\frac{\Delta [	ext{O}_3]}{\Delta t}$$

Question 4

Which laboratory technique is most appropriate for monitoring the concentration of colored species during a reaction?

Accepted Answer

Spectroscopy

Question 5

Given the reaction $$	ext{H}_2 (g) + 	ext{I}_2 (g) ightarrow 2	ext{HI} (g)$$, if $$[	ext{H}_2]$$ decreases by $$0.28\,	ext{M} in$$ $$40\,	ext{s}$$, what is the rate of formation of HI?

Accepted Answer

$$0.007\,	ext{M/s}$$

Question 6

For the rate law $$	ext{Rate} = k[	ext{NO}]^2[	ext{O}_2]$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 7

If the rate constant $$k$$ for a reaction has units of $$	ext{M}^{-1}	ext{s}^{-1}$$, what is the order of the reaction?

Accepted Answer

Second order

Question 8

A first-order reaction has a half-life of $$10$$ minutes. How much of a $$40.0\,	ext{g}$$ sample remains after $$30$$ minutes?

Accepted Answer

$$5.0\,	ext{g}$$

Question 9

Which of the following changes will increase the rate of a chemical reaction according to collision theory?

Accepted Answer

Increasing the surface area of a solid reactant

Question 10

The Arrhenius equation is $$k = Ae$$^{-E_A/(RT)}$$. If the activation energy E_A$ increases, what happens to the rate constant k$ (assuming all other factors remain constant)?

Accepted Answer

$$k$$ decreases

Question 11

A reaction is found to have a rate constant $$k = 4.60 	imes 10$$^{-6}$$\,	ext{s}^{-1} at$$ $$275\,	ext{K}$$ and an activation energy of $$108\,	ext{kJ/mol}. $$What is the rate constant at $$366\,	ext{K}$$? (Use $$R = 8.314\,	ext{J/(mol\,K)})$$

Accepted Answer

$$11.7\,	ext{s}^{-1}$$

Question 12

Which of the following statements about catalysts is TRUE?

Accepted Answer

Catalysts provide an alternative pathway with lower activation energy.

Question 13

For a reaction mechanism, which step determines the overall rate law?

Accepted Answer

The slowest (rate-determining) step

Question 14

Which of the following is an intermediate in a reaction mechanism?

Accepted Answer

A species that is produced in one step and consumed in a later step, not appearing in the overall reaction

Question 15

The decomposition of $$	ext{NO}_2 is $$second order with respect to $$	ext{NO}_2. $$Which integrated rate law should be used to determine $$[	ext{NO}_2] at $$any time $$t$$?

Accepted Answer

$$\frac{1}{[	ext{NO}_2]_t} = kt + \frac{1}{[	ext{NO}_2]_0}$$

Question 16

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

Accepted Answer

It increases the kinetic energy and frequency of effective collisions.

Question 17

A reaction has a rate law $$	ext{Rate} = k[	ext{A}]^0. $$What will happen to the rate if the concentration of A is doubled?

Accepted Answer

The rate will remain the same.

Question 18

Which of the following is a correct statement about the units of the rate constant $$k$$ for a third-order reaction?

Accepted Answer

$$	ext{M}^{-2}	ext{s}^{-1}$$

Question 19

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

The color of the reactants

Chemical Kinetics: Reaction Rates and Rate Laws

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