Question 1

Which of the following changes would NOT increase the rate of combustion in a campfire, as illustrated by the images of tinder, kindling, gasoline, and hot coals?

Accepted Answer

Covering the fire with a metal lid to reduce oxygen supply

Question 2

For the reaction $$8\ \mathrm{H_2S}(g) + 4\ \mathrm{O_2$}(g) \rightarrow 8\ \mathrm{H_2O}(g) + \mathrm{S_8$}(g)$$, if $$\frac{\Delta [\mathrm{H_2S}]}{\Delta t} = -0.080\ \mathrm{M/s}$$, what is $$\frac{\Delta [\mathrm{O_2$}]}{\Delta t}$$?

Accepted Answer

$$-0.040\ \mathrm{M/s}$$

Question 3

Which of the following best describes the rate law for a reaction that is first order in A and second order in B?

Accepted Answer

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

Question 4

A plot of $$\ln [A]$$ versus time yields a straight line with a negative slope for a reaction. What is the order of the reaction with respect to A?

Accepted Answer

First order

Question 5

The decomposition of $$\mathrm{SO_2Cl_2} is $$first order with a rate constant $$k = 1.42 	imes 10$$^{-4}$$\ \mathrm{s}^{-1}. $$What is the half-life of $$\mathrm{SO_2Cl_2}$$?

Accepted Answer

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

Question 6

Which of the following statements about catalysts is TRUE?

Accepted Answer

Catalysts provide an alternative pathway with a lower activation energy.

Question 7

Given the reaction $$2A + B \rightarrow 3C$$, if A is decreasing at a rate of $$0.100\ \mathrm{M/s}$$, how fast is C increasing?

Accepted Answer

$$0.150\ \mathrm{M/s}$$

Question 8

Which of the following is the correct integrated rate law for a second-order reaction ($$A \rightarrow$$ products)?

Accepted Answer

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

Question 9

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

Accepted Answer

The frequency of collisions with proper orientation

Question 10

A reaction is monitored and a plot of $$[A]$$ versus time yields a straight line. What is the order of the reaction?

Accepted Answer

Zero order

Question 11

For the reaction $$aA + bB \rightarrow cC + dD$$, which of the following correctly expresses the rate in terms of the change in concentration of B?

Accepted Answer

$$\mathrm{Rate} = -\frac{1}{b} \frac{\Delta [B]}{\Delta t}$$

Question 12

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

Accepted Answer

It increases the average kinetic energy, leading to more collisions with energy greater than $$E_a.$$

Question 13

A reaction is found to be zero order in A. If the initial concentration of A is doubled, what happens to the rate?

Accepted Answer

It remains the same.

Question 14

Which of the following is a reaction intermediate in the mechanism below?
NO$$_2(g) + NO$_2(g$$) → NO$$_3(g) + NO(g) ($$slow)
CO(g) + NO$$_3(g$$) → CO$$_2(g) + NO$_2(g) ($$fast)

Accepted Answer

NO$$_3$$

Question 15

For a first-order reaction, what is the relationship between half-life and the rate constant?

Accepted Answer

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

Question 16

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

Accepted Answer

The concentration of the products

Question 17

A reaction has the rate law $$\mathrm{Rate} = k[\mathrm{A}]^1[\mathrm{B}]^2. If $$the concentration of A is doubled and B is tripled, by what factor does the rate increase?

Accepted Answer

12

Question 18

Which of the following best describes the effect of a catalyst on a reaction mechanism?

Accepted Answer

It provides an alternative pathway with a lower activation energy.

Question 19

Which of the following is the correct unit for the rate constant $$k$$ for a second-order reaction?

Accepted Answer

$$\mathrm{M}^{-1}\mathrm{s}^{-1}$$

Step-by-Step Guidance for Question 53: First-Order Reaction Analysis

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