Q: For the reaction $$2 ext{HI}(g) \rightarrow ext{H}_2(g) + ext{I}_2(g)$$, how is the rate of disappearance of HI related to the rate of appearance of $$\text{H}_2$$?

The rate of HI disappearance is twice the rate of $$\text{H}_2$$ appearance.

Q: The decomposition of NO$$_2 is $$second order in NO$$_2. If $$the initial concentration is $$0.500 \text{ M}$$ and after $$60.0$$ min the concentration is $$0.200 \text{ M}$$, what is the value of the rate constant $$k$$? Use $$t = 60.0 \text{ min} = 3600 \text{ s}$$ and the integrated rate law $$\frac{1}{[A]} = kt + \frac{1}{[A]_0}.$$

$$k = 0.00278 \text{ M}^{-1}\text{s}^{-1}$$

Question 1

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

Accepted Answer

Grinding the solid reactant into a fine powder

Question 2

For the reaction $$2 	ext{HI}(g) ightarrow 	ext{H}_2(g) + 	ext{I}_2(g)$$, how is the rate of disappearance of HI related to the rate of appearance of $$	ext{H}_2$$?

Accepted Answer

The rate of HI disappearance is twice the rate of $$	ext{H}_2$$ appearance.

Question 3

A reaction has the rate law $$	ext{Rate} = k[A]^2. If $$the concentration of A is doubled, by what factor does the reaction rate increase?

Accepted Answer

It increases by a factor of 4

Question 4

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

Accepted Answer

It provides an alternative pathway with lower activation energy.

Question 5

Given the reaction $$2 	ext{O}_3(g) ightarrow 3 	ext{O}_2(g)$$, if the rate of disappearance of ozone is $$0.10 	ext{ M/s}$$, what is the rate of appearance of oxygen?

Accepted Answer

$$0.15 	ext{ M/s}$$

Question 6

Which of the following is true for a first-order reaction with respect to reactant A?

Accepted Answer

Doubling [A] doubles the rate.

Question 7

A reaction has the rate law $$	ext{Rate} = k[A][B]^0. $$What is the overall order of the reaction?

Accepted Answer

First order

Question 8

For a first-order reaction, which plot will yield a straight line?

Accepted Answer

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

Question 9

The decomposition of NO$$_2 is $$second order in NO$$_2. If $$the initial concentration is $$0.500 	ext{ M}$$ and after $$60.0$$ min the concentration is $$0.200 	ext{ M}$$, what is the value of the rate constant $$k$$? Use $$t = 60.0 	ext{ min} = 3600 	ext{ s}$$ and the integrated rate law $$\frac{1}{[A]} = kt + \frac{1}{[A]_0}.$$

Accepted Answer

$$k = 0.00278 	ext{ M}^{-1}	ext{s}^{-1}$$

Question 10

Which of the following is a correct statement about the half-life of a first-order reaction?

Accepted Answer

It is independent of the initial concentration of the reactant.

Question 11

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

Accepted Answer

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

Question 12

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

Question 13

Which of the following is true about intermediates in a reaction mechanism?

Accepted Answer

They are produced in one step and consumed in another.

Question 14

For a reaction with the rate law $$	ext{Rate} = k[A][B]$$, what is the molecularity of the elementary step?

Accepted Answer

Bimolecular

Question 15

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

Accepted Answer

It increases the frequency and energy of collisions.

Question 16

A student is studying the decomposition of $$	ext{SO}_2	ext{Cl}_2$$ which follows first-order kinetics with $$k = 4.50 	imes 10$$^{-3}$$ 	ext{ s}^{-1}. If $$the initial concentration is $$4.00 	ext{ M}$$, what is the concentration after $$2.00$$ minutes? Use $$\ln[A] = -kt + \ln[A]_0.$$

Accepted Answer

$$2.33 	ext{ M}$$

Question 17

Which of the following is a characteristic of a heterogeneous catalyst?

Accepted Answer

It is in a different phase than the reactants.

Question 18

In the enzyme-substrate model, what is the name of the region where the substrate binds to the enzyme?

Accepted Answer

Active site

Question 19

Which of the following is true for a zero-order reaction?

Accepted Answer

The rate is constant and independent of reactant concentration.

Chemical Kinetics: Rates, Laws, and Mechanisms

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