Question 1

Which of the following changes will generally increase the rate of a chemical reaction involving a solid and a liquid reactant?

Accepted Answer

Grinding the solid reactant to a fine powder

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

Which of the following best describes a first-order reaction?

Accepted Answer

Doubling the concentration of reactant doubles the rate

Question 4

A reaction is found to have the rate law $$	ext{Rate} = k[A][B]^2. $$What is the overall order of the reaction?

Accepted Answer

Third order

Question 5

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

Accepted Answer

$$1/[A] vs. $$time

Question 6

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

Accepted Answer

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

Question 7

A reaction has the integrated rate law $$\ln\dfrac{[A]_t}{[A]_0} = -kt. If $$the initial concentration of $$A is 0.200 M $$and after 50 s it is 0.050 M, what is the value of $$k$$?

Accepted Answer

$$0.0277\ 	ext{s}^{-1}$$

Question 8

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

Accepted Answer

Increasing temperature increases the fraction of molecules with energy greater than $$E_a$$

Question 9

According to collision theory, which of the following is necessary for a chemical reaction to occur?

Accepted Answer

Reactant molecules must collide with correct orientation and sufficient energy

Question 10

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

Accepted Answer

The rate is independent of reactant concentration

Question 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

It provides an alternative pathway with lower activation energy

Question 13

In a multistep reaction mechanism, which step determines the overall rate of the reaction?

Accepted Answer

The slowest step

Question 14

For a first-order reaction, a plot of $$\ln[A]$$ versus time yields a straight line. What is the slope of this line?

Accepted Answer

$$-k$$

Question 15

The Arrhenius equation relates the rate constant $$k to $$temperature and activation energy. Which form of the equation allows you to determine $$E_a$$ from a graph?

Accepted Answer

$$\ln k = -\dfrac{E_a}{R}\dfrac{1}{T} + \ln A$$

Question 16

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

Accepted Answer

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

Question 17

Which of the following is a correct integrated rate law for a second-order reaction?

Accepted Answer

$$\dfrac{1}{[A]_t} = kt + \dfrac{1}{[A]_0}$$

Question 18

If a reaction is zero order, what is the relationship between concentration and time?

Accepted Answer

$$[A]_t = [A]_0 - kt$$

Question 19

Which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

Color of the reactants

Chemical Kinetics: Rates, Mechanisms, and Reaction Dynamics

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