Question 1

Which of the following changes will most likely increase the rate of a reaction between two gases in a closed container?

Accepted Answer

Increasing the concentration of one or both reactants

Question 2

For the reaction $$2HI(g) ightarrow H_2$(g) + I_2$(g)$$, if the rate of disappearance of HI is $$4.2 	imes 10$$^{-7}$$ M/s, what is the rate of appearance of I_2$?

Accepted Answer

$$2.1 	imes 10$$^{-7}$$ M/s

Question 3

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

Accepted Answer

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

Question 4

Which graph will yield a straight line for a first-order reaction?

Accepted Answer

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

Question 5

The half-life of a first-order reaction is given by which equation?

Accepted Answer

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

Question 6

A reaction has the following rate law: $$	ext{Rate} = k[NO]^2[O_2$]. $$What are the units of the rate constant $$k$$?

Accepted Answer

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

Question 7

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

Accepted Answer

It increases the fraction of molecules with energy greater than $$E_a.$$

Question 8

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

Accepted Answer

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

Question 9

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It provides an alternative pathway with lower activation energy.

Question 10

The Arrhenius equation relates the rate constant $$k to $$temperature and activation energy. Which is the correct form of the equation?

Accepted Answer

$$k = Ae$$^{-E_a/RT}$$

Question 11

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

Accepted Answer

Step 1, because it is the slowest (rate-determining step)

Question 12

For a zero-order reaction, which statement is correct?

Accepted Answer

The rate is independent of reactant concentration.

Question 13

A student is studying the decomposition of $$NO_2 at$$ $$300^\circC. $$The graph of $$1/[NO_2$] vs. $$time is linear. What is the order of the reaction?

Accepted Answer

Second order

Question 14

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

Accepted Answer

Color of reactants

Question 15

In the reaction $$NH_4^+(aq$$) + $$NO_2^-(aq$$) \rightarrow $$N_2(g) + 2H_2O(l$$)$$, doubling the concentration of NH_4$^+$$ doubles the rate, and doubling $$NO_2$$^-$$ also doubles the rate. What is the overall order of the reaction?

Accepted Answer

Second order

Question 16

Which statement about reaction intermediates is correct?

Accepted Answer

They are formed in one step and consumed in another during the mechanism.

Question 17

A student measures the pressure of $$CH_3NC$$ over time as it converts to $$CH_3CN at$$ $$198.9^\circC. $$The graph of $$\ln P vs. $$time is linear. What is the value of the slope?

Accepted Answer

$$-k$$

Question 18

Which of the following best describes the molecularity of an elementary reaction involving two molecules of $$A$$ and one molecule of $$B$$?

Accepted Answer

Termolecular

Question 19

According to collision theory, which condition is necessary for a successful reaction between two molecules?

Accepted Answer

The molecules must collide with correct orientation and sufficient energy.

Chemical Kinetics: Rates, Mechanisms, and Reaction Dynamics

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