Q: Given the reaction mechanism: Step 1: $$NO_2$$ + $$F_2$$ \rightarrow NO_2F + F$$ (slow) Step 2: F$$ + $$NO_2$$ \rightarrow NO_2F$$ (fast) What is the rate law for the overall reaction?

$$\text{rate} = k[NO_2$][F_2$]$$

Question 1

According to collision theory, which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

The color of the reactant molecules

Question 2

Which equation best represents the fraction of collisions with sufficient energy to react, according to collision theory?

Accepted Answer

$$f = e$$^{\frac{-E_a}$${RT}}$$

Question 3

In the Arrhenius equation $$k = Ae$$^{\frac{-E_a}$${RT}}$$, what does the parameter $$A$$ represent?

Accepted Answer

The frequency factor

Question 4

A reaction has an activation energy of 251 kJ/mol and an enthalpy change $$\Delta H = +167 kJ/$$mol. What is the activation energy for the reverse reaction?

Accepted Answer

$$E_a($$reverse) = 84$ kJ/mol

Question 5

Which statement about the transition state (activated complex) is correct?

Accepted Answer

It represents the highest energy point along the reaction pathway

Question 6

For the reaction $$A + B \rightarrow C + D$$, if the reaction is elementary, what is the correct rate law?

Accepted Answer

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

Question 7

Which of the following best describes a bimolecular elementary reaction?

Accepted Answer

A reaction involving two molecules colliding in a single step

Question 8

Given the reaction mechanism:
Step 1: $$NO_2$$ + $$F_2$$ \rightarrow NO_2F + F$$ (slow)
Step 2: F$$ + $$NO_2$$ \rightarrow NO_2F$$ (fast)
What is the rate law for the overall reaction?

Accepted Answer

$$	ext{rate} = k[NO_2$][F_2$]$$

Question 9

Which of the following is true about the rate-determining step (RDS) in a reaction mechanism?

Accepted Answer

It determines the rate law for the overall reaction

Question 10

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

Accepted Answer

$$	ext{rate} = k[B][C]$$

Question 11

Which of the following is NOT a correct statement about elementary reactions?

Accepted Answer

The rate law must be determined experimentally

Question 12

For a generic exothermic reaction, which of the following is true about the potential energy diagram?

Accepted Answer

The products are at a lower energy than the reactants

Question 13

Using the Arrhenius equation, which of the following will increase the rate constant $$k$$ for a reaction?

Accepted Answer

Increasing the temperature

Question 14

Which of the following is the correct rearranged form of the Arrhenius equation to compare rate constants at two temperatures?

Accepted Answer

$$\ln\left(\frac{k_2$}{k_1$}\right) = \frac{E_a}{R}\left(\frac{1}{T_1$} - \frac{1}{T_2$}\right)$$

Question 15

Which of the following best describes a termolecular elementary reaction?

Accepted Answer

A reaction involving three molecules colliding in a single step

Question 16

In a reaction mechanism, why is the rate law for the overall reaction determined by the slowest step?

Accepted Answer

Because the slowest step limits how fast the products can be formed

Question 17

Which of the following is a correct statement about the effect of temperature on reaction rate according to collision theory?

Accepted Answer

The fraction of collisions with sufficient energy increases exponentially with temperature

Question 18

A reaction mechanism consists of three steps. Which step is most important for determining the overall rate law?

Accepted Answer

The slowest step

Question 19

Which of the following is true about the molecularity of an elementary reaction?

Accepted Answer

It is the number of molecules involved in a single molecular event

Chemical Kinetics: Collision Theory, Transition State Theory, and Reaction Mechanisms

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