Q: Given the reaction $$2\text{NO}_2(g) + \text{F}_2(g) \rightarrow 2\text{NO}_2\text{F}(g)$$, and the following initial rates: $$\begin{align*} [\text{NO}_2] = 0.10\,M, [\text{F}_2] = 0.10\,M, \text{Rate} = 0.0050\,M/s \\ [\text{NO}_2] = 0.20\,M, [\text{F}_2] = 0.10\,M, \text{Rate} = 0.020\,M/s \\ [\text{NO}_2] = 0.10\,M, [\text{F}_2] = 0.20\,M, \text{Rate} = 0.010\,M/s \end{align*}$$ What is the order of the reaction with respect to $$\text{NO}_2$$ and $$\text{F}_2$$?

Second order in $$\text{NO}_2$$, first order in $$\text{F}_2$$

Q: Which of the following is a correct expression for the average rate of disappearance of $$H_2 in $$the reaction $$H_2(g$$) + $$I_2(g$$) \rightarrow 2HI(g)$$?

$$\text{Rate} = -\frac{\Delta[H_2$]}{\Delta t}$$

Question 1

Which of the following best describes the meaning of the rate law for a reaction, as shown by $$	ext{Rate} = k[A]^n$$?

Accepted Answer

It shows the relationship between the rate of the reaction and the concentrations of the reactants, with each reactant raised to a power determined experimentally.

Question 2

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

Accepted Answer

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

Question 3

Given the reaction $$2	ext{NO}_2(g) + 	ext{F}_2(g) ightarrow 2	ext{NO}_2	ext{F}(g)$$, and the following initial rates:

$$\begin{align*}
[	ext{NO}_2] = 0.10\,M, [	ext{F}_2] = 0.10\,M, 	ext{Rate} = 0.0050\,M/s \
[	ext{NO}_2] = 0.20\,M, [	ext{F}_2] = 0.10\,M, 	ext{Rate} = 0.020\,M/s \
[	ext{NO}_2] = 0.10\,M, [	ext{F}_2] = 0.20\,M, 	ext{Rate} = 0.010\,M/s 
\end{align*}$$
What is the order of the reaction with respect to $$	ext{NO}_2$$ and $$	ext{F}_2$$?

Accepted Answer

Second order in $$	ext{NO}_2$$, first order in $$	ext{F}_2$$

Question 4

Which experimental technique would be most appropriate for continuously monitoring the concentration of a colored reactant during a reaction?

Accepted Answer

Spectrophotometry

Question 5

For the reaction $$A ightarrow 	ext{Products}$$, a plot of $$\ln[A]$$ versus time yields a straight line with a negative slope. What is the order of the reaction?

Accepted Answer

First order

Question 6

A first-order reaction has a half-life of 30 seconds. How long will it take for the concentration of the reactant to decrease to one-eighth of its initial value?

Accepted Answer

90 seconds

Question 7

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

Accepted Answer

Increasing the temperature

Question 8

The activation energy ($$E_a) $$for a reaction is 50 kJ/mol. If the temperature is increased, what happens to the rate constant $$k$$ according to the Arrhenius equation?

Accepted Answer

$$k$$ increases

Question 9

Which of the following statements about catalysts is TRUE?

Accepted Answer

Catalysts provide an alternative pathway with a lower activation energy.

Question 10

For the reaction $$2A ightarrow B$$, the rate law is found to be $$	ext{Rate} = k[A]^2. If $$the initial concentration of $$A is $$doubled, by what factor does the rate increase?

Accepted Answer

4

Question 11

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 12

Which of the following best explains why powdered solids react faster than blocks of the same substance?

Accepted Answer

Powdered solids have greater surface area for contact with other reactants.

Question 13

Which of the following is a correct expression for the average rate of disappearance of $$H_2 in $$the reaction $$H_2(g$$) + $$I_2(g$$) \rightarrow 2HI(g)$$?

Accepted Answer

$$	ext{Rate} = -\frac{\Delta[H_2$]}{\Delta t}$$

Question 14

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

Accepted Answer

The color of the reactants

Question 15

A reaction is zero order in $$A. If $$the initial concentration of $$A is 0.50 M $$and the rate constant $$k is$$ $$0.10\,M/s$$, how long will it take for $$A to $$decrease to 0.20 M?

Accepted Answer

$$3.0\,s$$

Question 16

Which of the following best describes an intermediate in a reaction mechanism?

Accepted Answer

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

Question 17

The Arrhenius equation is $$k = A e$$^{-E_a/RT}$$. What does the term A$ represent?

Accepted Answer

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

Question 18

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

Accepted Answer

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

Question 19

Which of the following is true for a reaction with the rate law $$	ext{Rate} = k$$?

Accepted Answer

The reaction is zero order and the rate is independent of reactant concentration.

Chemical Kinetics: Rates, Mechanisms, and Factors Affecting Reactions

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