Question 1

An elementary reaction is a simple, one-step process.

Accepted Answer

A) True 
 B)False

Question 2

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Accepted Answer

A) True 
 B)False

Question 3

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of −0.208 hr−1 results. What is the rate law for the reaction?

Accepted Answer

A) Rate = 0.208 hr −1 [sucrose] 2 
B) Rate = 0.208 hr −1 [sucrose] 
C) Rate = 0.0433 hr [sucrose] 2 
D) Rate = 0.0433 hr [sucrose] 
E) Rate = 0.208 mol L −1hr −1 [sucrose] 0 
A) Rate = 0.208 hr −1 [sucrose] 2 
B) Rate = 0.208 hr −1 [sucrose] 
C) Rate = 0.0433 hr [sucrose] 2 
D) Rate = 0.0433 hr [sucrose] 
E) Rate = 0.208 mol L −1hr −1 [sucrose] 0

Question 4

A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?

Accepted Answer

A) 0.94 
B) 0.87 
C) 0.75 
D) 0.13 
E) 0.063 
A) 0.94 
B) 0.87 
C) 0.75 
D) 0.13 
E) 0.063

Question 5

The greater the energy of activation, Ea, the faster will be the reaction.

Accepted Answer

A) True 
 B)False

Question 6

The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?

Accepted Answer

A) 0.52 hr 
B) 1.4 hr 
C) 12 hr 
D) 33 hr 
E) > 40 hr 
A) 0.52 hr 
B) 1.4 hr 
C) 12 hr 
D) 33 hr 
E) > 40 hr

Question 7

Which one of the following sets of units is appropriate for a third-order rate constant?

Accepted Answer

A) s −1 
B) mol L −1s −1 
C) L mol −1s −1 
D) L 2 mol −2s −1 
E) L 3 mol −3s −1 
A) s −1 
B) mol L −1s −1 
C) L mol −1s −1 
D) L 2 mol −2s −1 
E) L 3 mol −3s −1

Question 8

A study of the decomposition reaction 3RS2 → 3R + 6S yields the following initial rate data.   What is the rate constant for the reaction?

Accepted Answer

A) 0.0103 L mol −1s −1 
B) 0.263 L mol −1s −1 
C) 0.571 L mol −1s −1 
D) 1.17 L mol −1s −1 
E) 1.75 L mol −1s −1 
A) 0.0103 L mol −1s −1 
B) 0.263 L mol −1s −1 
C) 0.571 L mol −1s −1 
D) 1.17 L mol −1s −1 
E) 1.75 L mol −1s −1

Question 9

A reaction has an activation energy of 195.0 kJ/mol. When the temperature is increased from 200°C to 220°C, the rate constant will increase by a factor of

Accepted Answer

A) 1.1. 
B) 4.3 × 10 4. 
C) 3.2. 
D) 7.5. 
E) None of these choices are correct. 
A) 1.1. 
B) 4.3 × 10 4. 
C) 3.2. 
D) 7.5. 
E) None of these choices are correct.

Question 10

In the lock and key model of enzyme action, the active site on the enzyme provides an exact fit for the substrate.

Accepted Answer

A) True 
 B)False

Question 11

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10−4 day−1. How many days does it take for 15% of the original ingredient to decompose?

Accepted Answer

A) 730 days 
B) 414 days 
C) 365 days 
D) 180 days 
E) 78 days 
A) 730 days 
B) 414 days 
C) 365 days 
D) 180 days 
E) 78 days

Question 12

A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Accepted Answer

A) [R] vs. 1/time 
B) 1/[R] vs. time 
C) [R] 2 vs. time 
D) 1/[R] 2 vs. time 
E) ln[R] vs. time 
A) [R] vs. 1/time 
B) 1/[R] vs. time 
C) [R] 2 vs. time 
D) 1/[R] 2 vs. time 
E) ln[R] vs. time

Question 13

Carbon-14 is a radioactive isotope which decays with a half-life of 5730 years. What is the first-order rate constant for its decay, in units of years−1?

Accepted Answer

A) 5.25 × 10 −5 years −1 
B) 1.21 × 10 −4 years −1 
C) 1.75 × 10 −4 years −1 
D) 3.49 × 10 −4 years −1 
E) 3.97 × 10 3 years −1 
A) 5.25 × 10 −5 years −1 
B) 1.21 × 10 −4 years −1 
C) 1.75 × 10 −4 years −1 
D) 3.49 × 10 −4 years −1 
E) 3.97 × 10 3 years −1

Question 14

The rate law for the reaction 3A → 2B is rate = k[A] with a rate constant of 0.0447 hr−1. What is the half-life of the reaction?

Accepted Answer

A) 0.0224 hr 
B) 0.0645 hr 
C) 15.5 hr 
D) 22.4 hr 
E) 44.7 hr 
A) 0.0224 hr 
B) 0.0645 hr 
C) 15.5 hr 
D) 22.4 hr 
E) 44.7 hr

Question 15

Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2  ⇄ H2O+−OH (rapid equilibrium)H2O+−OH + Br− → HOBr + H2O (slow)HOBr + H+ + Br− → Br2 + H2O (fast)
Which of the following rate laws is consistent with the mechanism?

Accepted Answer

A) Rate = k[H 2O 2][H +] 2[Br −] 
B) Rate = k[H 2O +−OH][Br −] 
C) Rate = k[H 2O 2][H +][Br −] 
D) Rate = k[HOBr][H +][Br −][H 2O 2] 
E) Rate = k[Br −] 
A) Rate = k[H 2O 2][H +] 2[Br −] 
B) Rate = k[H 2O +−OH][Br −] 
C) Rate = k[H 2O 2][H +][Br −] 
D) Rate = k[HOBr][H +][Br −][H 2O 2] 
E) Rate = k[Br −]

Question 16

The rate constant for the reaction 3A → 4B is 6.00 × 10−3 L mol−1min−1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?

Accepted Answer

A) 2.2 × 10 −3 min 
B) 5.5 × 10 −3 min 
C) 180 min 
D) 440 min 
E) 5.0 × 10 2 min 
A) 2.2 × 10 −3 min 
B) 5.5 × 10 −3 min 
C) 180 min 
D) 440 min 
E) 5.0 × 10 2 min

Question 17

The rate law cannot be predicted from the stoichiometry of a reaction.

Accepted Answer

A) True 
 B)False

Question 18

For the reaction A(g) + 2B(g) → 2C(g) + 2D(g)
The following data were collected at constant temperature. Determine the correct rate law for this reaction.

Accepted Answer

A) Rate = k[A] [B] 
B) Rate = k[A] 2 [B] 
C) Rate = k[A] [B] 2 
D) Rate = k[A] 
E) Rate = k[A] 3 
A) Rate = k[A] [B] 
B) Rate = k[A] 2 [B] 
C) Rate = k[A] [B] 2 
D) Rate = k[A] 
E) Rate = k[A] 3

Exam 16: Kinetics: Rates and Mechanisms of Chemical Reactions

An elementary reaction is a simple, one-step process.

A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of −0.208 hr−1 results. What is the rate law for the reaction?

A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?

The greater the energy of activation, Ea, the faster will be the reaction.

The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?

Which one of the following sets of units is appropriate for a third-order rate constant?

A study of the decomposition reaction 3RS2 → 3R + 6S yields the following initial rate data. What is the rate constant for the reaction?

A reaction has an activation energy of 195.0 kJ/mol. When the temperature is increased from 200°C to 220°C, the rate constant will increase by a factor of

In the lock and key model of enzyme action, the active site on the enzyme provides an exact fit for the substrate.

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10−4 day−1. How many days does it take for 15% of the original ingredient to decompose?

A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?

Carbon-14 is a radioactive isotope which decays with a half-life of 5730 years. What is the first-order rate constant for its decay, in units of years−1?

The rate law for the reaction 3A → 2B is rate = k[A] with a rate constant of 0.0447 hr−1. What is the half-life of the reaction?

The rate constant for the reaction 3A → 4B is 6.00 × 10−3 L mol−1min−1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?

The rate law cannot be predicted from the stoichiometry of a reaction.

For the reaction A(g) + 2B(g) → 2C(g) + 2D(g) The following data were collected at constant temperature. Determine the correct rate law for this reaction.

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and Reaction Direction

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of −0.208 hr⁻¹ results. What is the rate law for the reaction?

The decomposition of SOCl₂ is first-order in SOCl₂. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl₂to drop from 0.36 M to 0.045 M?

A study of the decomposition reaction 3RS₂→ 3R + 6S yields the following initial rate data. What is the rate constant for the reaction?

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10⁻⁴ day⁻¹. How many days does it take for 15% of the original ingredient to decompose?

Carbon-14 is a radioactive isotope which decays with a half-life of 5730 years. What is the first-order rate constant for its decay, in units of years⁻¹?

The rate law for the reaction 3A → 2B is rate = k[A] with a rate constant of 0.0447 hr⁻¹. What is the half-life of the reaction?

The rate constant for the reaction 3A → 4B is 6.00 × 10⁻³ L mol⁻¹min⁻¹. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?