Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH3Cl ↔ CH3OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

A) The Keq at 25°C for this reaction is very large, in other words this reaction proceeds to near completion as written, left to right under standard conditions. B) The Keq at 25°C for this reaction is very small (3OH and Cl-). In other words there is more product than at 25°C. D) At 250°C the equilibrium concentration of products and reactants is nearly the same. E) Both A and C are correct. A) The Keq at 25°C for this reaction is very large, in other words this reaction proceeds to near completion as written, left to right under standard conditions. B) The Keq at 25°C for this reaction is very small (3OH and Cl-). In other words there is more product than at 25°C. D) At 250°C the equilibrium concentration of products and reactants is nearly the same. E) Both A and C are correct.

In the reaction of Cl2 with ethane and UV light, which of the following reactions would be a propagation event(s)? I. Cl∙ + CH3-CH3 → CH3-CH2-Cl + H∙ II. Cl∙ + CH3-CH3 → CH3-H2C∙ + HCl III. Cl∙ + CH3-H2C∙ → CH3-CH2-Cl IV. Cl2 + CH3-H2C∙ → CH3-CH2-Cl + Cl∙ V. Cl2 + UV light → C l∙ + Cl∙

A) reactions I and V B) reactions II, III and IV C) reactions I and IV D) reactions II and IV E) reactions I, II and IV A) reactions I and V B) reactions II, III and IV C) reactions I and IV D) reactions II and IV E) reactions I, II and IV

Exam 4: The Study of Chemical Reactions

Does one expect ΔS° in a propagation step of the free-radical chlorination of methane to be greater than zero, less than zero, or approximately equal to zero? Briefly explain your choice.

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Question 1

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The propagation steps of the free-radical chlorination of methane are shown
below.
CH₄ + Cl∙ → CH₃∙ + H-Cl
CH₃∙ + Cl-Cl → CH₃Cl + Cl∙
In each of the steps, two reactant molecules generate two product molecules. This similarity in the number of molecular species means that the disorder in the reaction is neither greatly increased nor diminished. Therefore, one expects ΔS° in either propagation step to be approximately equal to zero.

Write the structures of all of the monobromination products of 1,1,3,3-tetramethylcyclobutane.

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Consider the three-step mechanism for the reaction of A through intermediates B and C to produce D shown below. A → B E_a = 15 kcal/mol, ΔH° = 13 kcal/mol B → C E_a = 10 kcal/mol, ΔH° = -6 kcal/mol C → D E_a = 2 kcal/mol, ΔH° = -20 kcal/mol What's the enthalpy difference between reactant A and intermediate C?

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Question 3

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+7 kcal/mol

Which of the following correctly expresses the standard Gibbs free energy change of a reaction in terms of the reaction temperature (T) and equilibrium constant (K)?

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Question 4

Write a detailed, stepwise mechanism for the following reaction.

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Question 5

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH₃Cl ↔ CH₃OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

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Question 6

Explain how the termination step in a free-radical chain reaction stops the chain.

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Question 7

What is the hybridization of the negatively charged carbon in (CH₃)₃C:^-?

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Question 8

In the reaction of Cl₂ with ethane and UV light, which of the following reactions would be a propagation event(s)? I. Cl∙ + CH₃-CH₃→ CH₃-CH₂-Cl + H∙ II. Cl∙ + CH₃-CH₃→ CH₃-H₂C∙ + HCl III. Cl∙ + CH₃-H₂C∙ → CH₃-CH₂-Cl IV. Cl₂ + CH₃-H₂C∙ → CH₃-CH₂-Cl + Cl∙ V. Cl_{2 + UV light}→ C l∙ + Cl∙

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Question 9

Given a K of 0.45 at 25°C, calculate the corresponding DG°in kJ/mol. [R = 8.314 J/K∙ mol]

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Question 10

How many secondary hydrogens are present in the hydrocarbon below?

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Question 11

If the equilibrium constant (K_eq) of a reaction is 0.5 then which of the following that must be true?

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Question 12

What is the hybridization of the positively charged carbon in (CH₃)₃C⁺?

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Question 13

Predict the major monobromination product in the following reaction. (CH₃)₃CCH₂CH₃ + Br₂

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Question 14

Which H atom in the molecule shown will be most readily abstracted by a bromine radical?

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Question 15

When the reaction between methane and chlorine is photochemically initiated, which of the following compounds $\underline{\text{ cannot }}$ be formed through a termination reaction?

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Question 16

The rate of a reaction typically increases as the temperature increases because:

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Question 17

If a reaction is exothermic, then:

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Question 18

The relative reactivity of the 1°: 2°: 3° hydrogens of (CH₃)₃CCH₂CH₃ in free radical chlorination is 1: 3.8: 5.0. Provide the structure of each monochlorination product, and estimate the relative amount of each in the mixture of monochlorinated products.

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Question 19

Consider the transformation of A to B (i.e., A → B). If at equilibrium at 25°C the concentration of A is 20% of the initial concentration of A, determine the value of ΔG° (in kcal/mol) for this reaction. R = 1.987 cal/mol∙K.

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Question 20

Showing 1 - 20 of 128

Exam 4: The Study of Chemical Reactions

Does one expect ΔS° in a propagation step of the free-radical chlorination of methane to be greater than zero, less than zero, or approximately equal to zero? Briefly explain your choice.

Write the structures of all of the monobromination products of 1,1,3,3-tetramethylcyclobutane.

Which of the following correctly expresses the standard Gibbs free energy change of a reaction in terms of the reaction temperature (T) and equilibrium constant (K)?

Write a detailed, stepwise mechanism for the following reaction.

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH3Cl ↔ CH3OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

Explain how the termination step in a free-radical chain reaction stops the chain.

What is the hybridization of the negatively charged carbon in (CH3)3C:-?

Given a K of 0.45 at 25°C, calculate the corresponding DG° in kJ/mol. [R = 8.314 J/K∙ mol]

How many secondary hydrogens are present in the hydrocarbon below?

If the equilibrium constant (Keq) of a reaction is 0.5 then which of the following that must be true?

What is the hybridization of the positively charged carbon in (CH3)3C+?

Predict the major monobromination product in the following reaction. (CH3)3CCH2CH3 + Br2

Which H atom in the molecule shown will be most readily abstracted by a bromine radical?

When the reaction between methane and chlorine is photochemically initiated, which of the following compounds cannot ‾\underline{\text{ cannot }} cannot ​ be formed through a termination reaction?

The rate of a reaction typically increases as the temperature increases because:

If a reaction is exothermic, then:

The relative reactivity of the 1°: 2°: 3° hydrogens of (CH3)3CCH2CH3 in free radical chlorination is 1: 3.8: 5.0. Provide the structure of each monochlorination product, and estimate the relative amount of each in the mixture of monochlorinated products.

Consider the transformation of A to B (i.e., A → B). If at equilibrium at 25°C the concentration of A is 20% of the initial concentration of A, determine the value of ΔG° (in kcal/mol) for this reaction. R = 1.987 cal/mol∙K.

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

Consider the following substitution reaction with a ΔG° value of -91.1 kJ/mole. HO- + CH₃Cl ↔ CH₃OH + Cl- Given this information which of the following statements must be true? (R = 8.315 J/mole K)

What is the hybridization of the negatively charged carbon in (CH₃)₃C:^-?

Given a K of 0.45 at 25°C, calculate the corresponding DG°in kJ/mol. [R = 8.314 J/K∙ mol]

If the equilibrium constant (K_eq) of a reaction is 0.5 then which of the following that must be true?

What is the hybridization of the positively charged carbon in (CH₃)₃C⁺?

Predict the major monobromination product in the following reaction. (CH₃)₃CCH₂CH₃ + Br₂

When the reaction between methane and chlorine is photochemically initiated, which of the following compounds $\underline{\text{ cannot }}$ be formed through a termination reaction?

The relative reactivity of the 1°: 2°: 3° hydrogens of (CH₃)₃CCH₂CH₃ in free radical chlorination is 1: 3.8: 5.0. Provide the structure of each monochlorination product, and estimate the relative amount of each in the mixture of monochlorinated products.