Question 1

The rate determining step in the following mechanism is bimolecular

Accepted Answer

A) True 
 B)False

Question 2

At a particular temperature the first-order gas-phase reaction N2O5 $\rarr$2NO2 + 1/2O2 has a half-life for the disappearance of dinitrogen pentoxide of 5130 s.Suppose 0.450 atm of N2O5 is introduced into an evacuated 2.00 L flask.What will be the total gas pressure inside the flask after 3.00 hours?

Accepted Answer

A) 0.969 atm 
B) 0.105 atm 
C) 0.795 atm 
D) 1.14 atm 
E) 0.864 atm 
A) 0.969 atm 
B) 0.105 atm 
C) 0.795 atm 
D) 1.14 atm 
E) 0.864 atm

Question 3

For the first-order reaction 2N2O5 $\rarr$2N2O4 + O2 at a particular temperature, the half-life of N2O5 is 0.90 hr.What fraction of the initial concentration of N2O5 will remain after 2.4 hours?

Accepted Answer

Question 4

For the chemical reaction A $\rarr$ C, a plot of 1/[A]t versus time was found to give a straight line with a positive slope.What is the order of reaction?

Accepted Answer

A) zeroth 
B) first 
C) second 
D) Such a plot cannot reveal the order of the reaction. 
A) zeroth 
B) first 
C) second 
D) Such a plot cannot reveal the order of the reaction.

Question 5

Given the rate law for a reaction, rate = k[A][B]2, where rate is measured in units of M s-1, what are the units for the rate constant k?

Accepted Answer

Question 6

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M-1s-1, which equation should be used?

Accepted Answer

A) ln([A]t/[A]o)= - kt 
B) t1/2 = ln2/k 
C) [A]t = -kt + [A]o 
D) 1/[A]t = kt + 1/[A]o 
E) Rate = k[A] 
A) ln([A]t/[A]o)= - kt 
B) t1/2 = ln2/k 
C) [A]t = -kt + [A]o 
D) 1/[A]t = kt + 1/[A]o 
E) Rate = k[A]

Question 7

The isomerization of cyclopropane to form propene is a first-order reaction.   At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min.Determine the rate constant for this reaction at 760 K.

Accepted Answer

A) 3.66 × 10-2 min-1 
B) 1.04 × 10-2 min-1 
C) 2.42 min-1 
D) 2.06 × 10-3 min-1 
E) 2.40 × 10-2 min-1 
A) 3.66 × 10-2 min-1 
B) 1.04 × 10-2 min-1 
C) 2.42 min-1 
D) 2.06 × 10-3 min-1 
E) 2.40 × 10-2 min-1

Question 8

For the chemical reaction system described by the diagram below, which statement is true?

Accepted Answer

A) The forward reaction is endothermic. 
B) The activation energy for the forward reaction is greater than the activation energy for the reverse reaction. 
C) At equilibrium, the activation energy for the forward reaction is equal to the activation energy for the reverse reaction. 
D) The activation energy for the reverse reaction is greater than the activation energy for the forward reaction. 
E) The reverse reaction is exothermic. 
A) The forward reaction is endothermic. 
B) The activation energy for the forward reaction is greater than the activation energy for the reverse reaction. 
C) At equilibrium, the activation energy for the forward reaction is equal to the activation energy for the reverse reaction. 
D) The activation energy for the reverse reaction is greater than the activation energy for the forward reaction. 
E) The reverse reaction is exothermic.

Question 9

In general, to calculate the rate constant for a first order decomposition reaction, A $\rarr$ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

Accepted Answer

A) t1/2 = 1/(k[A]o) 
B) t1/2 = ln2/k 
C) [A]t = -kt + [A]o 
D) 1/[A]t = kt + 1/[A]o 
E) Rate = k[A] 
A) t1/2 = 1/(k[A]o) 
B) t1/2 = ln2/k 
C) [A]t = -kt + [A]o 
D) 1/[A]t = kt + 1/[A]o 
E) Rate = k[A]

Question 10

Appropriate units for a second-order rate constant are

Accepted Answer

A) M/s 
B) 1/M·s 
C) 1/s 
D) 1/M2·s 
A) M/s 
B) 1/M·s 
C) 1/s 
D) 1/M2·s

Question 11

A certain reaction A $\rarr$ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

Accepted Answer

A) 3.8 x 10-4 M-1min-1 
B) 1.9 x 10-3 M-1min-1 
C) 5.0 x 10-3 M-1min-1 
D) 2.3 x 10-2 M-1min-1 
E) 1.1 x 10-1 M-1min-1 
A) 3.8 x 10-4 M-1min-1 
B) 1.9 x 10-3 M-1min-1 
C) 5.0 x 10-3 M-1min-1 
D) 2.3 x 10-2 M-1min-1 
E) 1.1 x 10-1 M-1min-1

Question 12

The activation energy for the reaction O + O3 $\rarr$2O2 is 25 kJ/mol, and the enthalpy change is $\Delta$H = -388 kJ/mol.What is the activation energy for the decomposition of O2 by the reverse reaction?

Accepted Answer

A) 413 kJ 
B) 388 kJ 
C) 363 kJ 
D) 50 kJ 
E) 25 kJ 
A) 413 kJ 
B) 388 kJ 
C) 363 kJ 
D) 50 kJ 
E) 25 kJ

Question 13

Given the rate law for a reaction, rate = k[A]2, where rate is measured in units of M min-1, what are the units for the rate constant k?

Accepted Answer

Question 14

Concerning the rate law, Rate = k[A]0, what are appropriate units for the rate constant k?

Accepted Answer

A) s-1 
B) M-1s-1 
C) M-2s-1 
D) M/s 
E) M2/s 
A) s-1 
B) M-1s-1 
C) M-2s-1 
D) M/s 
E) M2/s

Question 15

The half life for a first order reaction is 27 min.How long will it take for 4 half lives to occur?

Accepted Answer

A) 53,000 min 
B) 108 min 
C) 81 min 
D) 260 min 
E) Not enough information given 
A) 53,000 min 
B) 108 min 
C) 81 min 
D) 260 min 
E) Not enough information given

Question 16

An experimental drug, D, is known to decompose in the blood stream.Tripling the concentration of the drug increases the decomposition rate by a factor of nine.Write the rate law for decomposition of D and give the units of the rate constant.

Accepted Answer

The rate law is rate = k[D]², a

Question 17

A reaction is experimentally found to follow the rate law, Rate = k[A]2 where k = 0.130 M-1min-1.Starting with [A]o = 2.50 M, how many seconds will it take for [A]t = 1.25 M

Accepted Answer

A) 3.08 s 
B) 185 s 
C) 5.33 s 
D) 320.s 
E) 577 
A) 3.08 s 
B) 185 s 
C) 5.33 s 
D) 320.s 
E) 577

Question 18

Concerning the rate law, Rate = k[A][B][C], what are appropriate units for the rate constant k?

Accepted Answer

A) s-1 
B) M-1s-1 
C) M-2s-1 
D) M/s 
E) M2/s 
A) s-1 
B) M-1s-1 
C) M-2s-1 
D) M/s 
E) M2/s

Question 19

At 25°C, the second-order reaction NOCl(g) $\rarr$NO(g)+ 1/2Cl2(g) is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

Accepted Answer

A) 8.22 hr 
B) 11.6 hr 
C) 15.5 hr 
D) 17.5 hr 
E) 23.0 hr 
A) 8.22 hr 
B) 11.6 hr 
C) 15.5 hr 
D) 17.5 hr 
E) 23.0 hr

Question 20

Calculate the activation energy, in kJ/mol, for the redox reaction 
Sn2+ + 2Co3+ $\rarr$ Sn4+ + 2Co2+.

Accepted Answer

A) 59.2 
B) 0.477 
C) 5.37 
D) 163 kJ 
E) 48.1 kJ 
A) 59.2 
B) 0.477 
C) 5.37 
D) 163 kJ 
E) 48.1 kJ

Exam 13: Chemical Kinetics

The rate determining step in the following mechanism is bimolecular

For the first-order reaction 2N2O5 →\rarr→ 2N2O4 + O2 at a particular temperature, the half-life of N2O5 is 0.90 hr.What fraction of the initial concentration of N2O5 will remain after 2.4 hours?

For the chemical reaction A →\rarr→ C, a plot of 1/[A]t versus time was found to give a straight line with a positive slope.What is the order of reaction?

Given the rate law for a reaction, rate = k[A][B]2, where rate is measured in units of M s-1, what are the units for the rate constant k?

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M-1s-1, which equation should be used?

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min.Determine the rate constant for this reaction at 760 K.

For the chemical reaction system described by the diagram below, which statement is true?

In general, to calculate the rate constant for a first order decomposition reaction, A →\rarr→ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

Appropriate units for a second-order rate constant are

A certain reaction A →\rarr→ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

The activation energy for the reaction O + O3 →\rarr→ 2O2 is 25 kJ/mol, and the enthalpy change is Δ\DeltaΔ H = -388 kJ/mol.What is the activation energy for the decomposition of O2 by the reverse reaction?

Given the rate law for a reaction, rate = k[A]2, where rate is measured in units of M min-1, what are the units for the rate constant k?

Concerning the rate law, Rate = k[A]0, what are appropriate units for the rate constant k?

The half life for a first order reaction is 27 min.How long will it take for 4 half lives to occur?

An experimental drug, D, is known to decompose in the blood stream.Tripling the concentration of the drug increases the decomposition rate by a factor of nine.Write the rate law for decomposition of D and give the units of the rate constant.

A reaction is experimentally found to follow the rate law, Rate = k[A]2 where k = 0.130 M-1min-1.Starting with [A]o = 2.50 M, how many seconds will it take for [A]t = 1.25 M

Concerning the rate law, Rate = k[A][B][C], what are appropriate units for the rate constant k?

At 25°C, the second-order reaction NOCl(g) →\rarr→ NO(g)+ 1/2Cl2(g) is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

Calculate the activation energy, in kJ/mol, for the redox reaction Sn2+ + 2Co3+ →\rarr→ Sn4+ + 2Co2+.

Chemistry: the Study of Change

Atoms, Molecules, and Ions

Mass Relationships in Chemical Reactions

Reactions in Aqueous Solutions

Gases

Thermochemistry

Quantum Theory and the Electronic Structure of Atoms

Periodic Relationships Among the Elements

Chemical Bonding I: Basic Concepts

Chemical Bonding Ii: Molecular Geometry and Hybridization of Atomic Orbitals

Intermolecular Forces and Liquids and Solids

Physical Properties of Solutions

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Entropy Free Energy and Equilibrium

Electrochemistry

Nuclear Chemistry

Chemistry in the Atmosphere

Metallurgy and the Chemistry of Metals

Nonmetallic Elements and Their Compounds

Transition Metal Chemistry and Coordination Compounds

Organic Chemistry

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Filters

For the first-order reaction 2N₂O₅ $\rarr$ 2N₂O₄ + O₂ at a particular temperature, the half-life of N₂O₅ is 0.90 hr.What fraction of the initial concentration of N₂O₅ will remain after 2.4 hours?

For the chemical reaction A $\rarr$ C, a plot of 1/[A]_t versus time was found to give a straight line with a positive slope.What is the order of reaction?

Given the rate law for a reaction, rate = k[A][B]², where rate is measured in units of M s^-1, what are the units for the rate constant k?

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M^-1s^-1, which equation should be used?

In general, to calculate the rate constant for a first order decomposition reaction, A $\rarr$ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

A certain reaction A $\rarr$ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

The activation energy for the reaction O + O₃ $\rarr$ 2O₂ is 25 kJ/mol, and the enthalpy change is $\Delta$ H = -388 kJ/mol.What is the activation energy for the decomposition of O₂ by the reverse reaction?

Given the rate law for a reaction, rate = k[A]², where rate is measured in units of M min^-1, what are the units for the rate constant k?

Concerning the rate law, Rate = k[A]⁰, what are appropriate units for the rate constant k?

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.130 M^-1min^-1.Starting with [A]_o = 2.50 M, how many seconds will it take for [A]_t = 1.25 M

At 25°C, the second-order reaction NOCl(g) $\rarr$ NO(g)+ ¹/₂Cl₂(g)is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

Calculate the activation energy, in kJ/mol, for the redox reaction Sn²⁺ + 2Co³⁺ $\rarr$ Sn⁴⁺ + 2Co²⁺. $Calculate the activation energy, in kJ/mol, for the redox reaction Sn<sup>2+</sup> + 2Co<sup>3+</sup> \rarr Sn<sup>4+</sup> + 2Co<sup>2+</sup>.$