Question 1

Explain how CFCs are linked to depletion of stratospheric ozone.

Accepted Answer

CFCs are persistent in the environment until they encounter ultraviolet light in the stratosphere. This interaction with a UV photon will cleave the C-Cl bond in the CFC and generate a chlorine radical. The chlorine radical reacts with ozone to form chlorine monoxide radical and molecular oxygen. The chlorine monoxide radical then reacts with a molecule of ozone to produce oxygen and to regenerate a chlorine radical. The two steps are the propagating steps in a radical chain reaction whereby a single chlorine radical can destroy about 100,000 ozone molecules.

Question 2

An alkane with the molecular formula C5H10 forms only one monochlorinated product when heated with Cl2/hv. Give the structure and the IUPAC name for this alkane.

Accepted Answer

Question 3

Give the best product for the reaction.

Accepted Answer

The answer of Give the best product for the reaction....

Question 4

Which of the following does not occur in a propagation step in the free radical bromination of ethane to form bromoethane?

Accepted Answer

A) a C-H bond breaks 
B) a Br-H bond forms 
C) a C-Br bond forms 
D) a Br-Br bond breaks 
E) a C-C bond breaks 
A) a C-H bond breaks 
B) a Br-H bond forms 
C) a C-Br bond forms 
D) a Br-Br bond breaks 
E) a C-C bond breaks

Question 5

When petroleum is distilled, the fraction that contains compounds with 5 to 11 carbons is known as ________.

Accepted Answer

A) natural gas 
B) asphalt 
C) diesel oil 
D) gasoline 
E) jet fuel 
A) natural gas 
B) asphalt 
C) diesel oil 
D) gasoline 
E) jet fuel

Question 6

Identify as initiation, propagation, or termination.

Accepted Answer

A) initiation = b; propagation = a, c, g; termination = d, e, f 
B) initiation = c, d, e; propagation = b; termination = a, f 
C) initiation = b; propagation = c, d, e; termination = a, f 
D) initiation = b; propagation = a, f; termination = c, d, e 
E) initiation = a, f; propagation = c, d, e; termination = b 
A) initiation = b; propagation = a, c, g; termination = d, e, f 
B) initiation = c, d, e; propagation = b; termination = a, f 
C) initiation = b; propagation = c, d, e; termination = a, f 
D) initiation = b; propagation = a, f; termination = c, d, e 
E) initiation = a, f; propagation = c, d, e; termination = b

Question 7

Why are alkanes so unreactive?

Accepted Answer

They have only stron

Question 8

Show the propagating steps in the addition of HBr to 1-pentene in the presence of peroxide.

Accepted Answer

The answer of Show the propagating steps in the addition...

Question 9

Give the best product for the reaction.

Accepted Answer

The answer of Give the best product for the reaction....

Question 10

When (R)-2-chlorobutane reacts with Br2/hv, which of the following is true?

Accepted Answer

A) Only I is formed. 
B) Only II is formed. 
C) Both I and II are formed in equal amounts. 
D) Both I and II are formed in unequal amounts. 
E) Both I and II could never form under these conditions. 
A) Only I is formed. 
B) Only II is formed. 
C) Both I and II are formed in equal amounts. 
D) Both I and II are formed in unequal amounts. 
E) Both I and II could never form under these conditions.

Question 11

The reaction Br2 + CH3Br → CH2Br2 + HBr was carried out. Which of the following mechanism steps is productive, but relatively unlikely to occur?

Accepted Answer

A) Br ∙ + CH3Br → HBr + ∙ CH2Br 
B) Br ∙ + ∙ CH2Br → CH2Br2 
C) Br ∙ + Br2 → Br2 + Br ∙ 
D) Br ∙ + ∙ CH3 → CH3Br 
A) Br ∙ + CH3Br → HBr + ∙ CH2Br 
B) Br ∙ + ∙ CH2Br → CH2Br2 
C) Br ∙ + Br2 → Br2 + Br ∙ 
D) Br ∙ + ∙ CH3 → CH3Br

Question 12

Provide the major organic product of the following reactions.

Accepted Answer

The answer of Provide the major organic product of the...

Question 13

When (R)-2-bromobutane reacts with Cl2/hv, which of the following is true?   I II

Accepted Answer

A) Only I is formed. 
B) Only II is formed. 
C) I and II are formed in equal amounts. 
D) I and II are formed in unequal amounts. 
E) I and II could never form under these conditions. 
A) Only I is formed. 
B) Only II is formed. 
C) I and II are formed in equal amounts. 
D) I and II are formed in unequal amounts. 
E) I and II could never form under these conditions.

Question 14

Rank the following fractions which result from the fractional distillation of petroleum in order of increasing boiling point: asphalt, gasoline, kerosene, natural gas, heating oil.

Accepted Answer

natural gas < gasoli

Question 15

Which of the following is the most stable radical?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 16

Which of the following products result from the disproportionation reaction between two propyl radicals?

Accepted Answer

A)    
B) CH3CH2CH3 + CH3CHCH3 
C) CH3CH2CH2CH2CH2CH3 
D) CH3CH2CH3 + CH2     CHCH3 
E) CH2     C   CH2 + CH3CH2CH3 
A)    
B) CH3CH2CH3 + CH3CHCH3 
C) CH3CH2CH2CH2CH2CH3 
D) CH3CH2CH3 + CH2     CHCH3 
E) CH2     C   CH2 + CH3CH2CH3

Question 17

When Br ∙ reacts with 1-butene (CH3CH2CH   CH2), the hydrogen atom which is preferentially abstracted is the one which produces a resonance stabilized radical. Draw the major resonance contributing forms of this radical.

Accepted Answer

∙ ∙ CH₃CHCH

Question 18

Consider the following monobromination reaction, then answer the following questions.   
a) Give the structures and the IUPAC names for the products.
b) Give the common names for the products.
c) Calculate ΔH° for the overall reaction using the following data for the indicated bond dissociation energies:   d) Calculate the percent yield for each product. (relative rate of abstraction of 3° hydrogen is 1600; 2° is 82; and 1° is 1.)
e) Propose a step-by-step mechanism for the major product only.
f) Draw a schematic potential energy diagram for the rate-determining step (RDS)only.
g) Does the transition state of the RDS resemble more closely the reactants or the products?
h) Would the value of the activation energy be different for different alkanes? Explain.
i) Would the reaction slow down or speed up if I2 is used instead of Br2? Explain.

Accepted Answer

a) @#IMG-DLM&_TB1830_00 b) @#IMG-DLM&_TB1830_00 c) ΔH° for 2

Question 19

Which of the following is true about the halogenation of methane, CH4?

Accepted Answer

A) The activation energy for F ∙ + CH4 → ∙ CH3 + HF is larger than any other halogen. 
B) O2 slows these reactions by inhibiting the termination step. 
C) The activation energy for I ∙ + CH4 → ∙ CH3 + HI is relatively small. 
D) The reaction must take place in the liquid state. 
E) I2 is unreactive because the activation energy for I ∙ + CH4 → ∙ CH3 + HI is relatively large. 
A) The activation energy for F ∙ + CH4 → ∙ CH3 + HF is larger than any other halogen. 
B) O2 slows these reactions by inhibiting the termination step. 
C) The activation energy for I ∙ + CH4 → ∙ CH3 + HI is relatively small. 
D) The reaction must take place in the liquid state. 
E) I2 is unreactive because the activation energy for I ∙ + CH4 → ∙ CH3 + HI is relatively large.

Question 20

The reaction Br2 + CH3Br → CH2Br2 + HBr was carried out. Which of the following mechanism steps is both productive and relatively likely to occur?

Accepted Answer

A) Br ∙ + ∙ CH2Br → CH2Br2 
B) Br ∙ + ∙ CH3 → CH3Br 
C) Br ∙ + Br2 → Br2 + Br ∙ 
D) Br ∙ + CH3Br → HBr + ∙ CH2Br 
A) Br ∙ + ∙ CH2Br → CH2Br2 
B) Br ∙ + ∙ CH3 → CH3Br 
C) Br ∙ + Br2 → Br2 + Br ∙ 
D) Br ∙ + CH3Br → HBr + ∙ CH2Br

Exam 13: Reactions of Alkanes, Radicals

Explain how CFCs are linked to depletion of stratospheric ozone.

An alkane with the molecular formula C5H10 forms only one monochlorinated product when heated with Cl2/hv. Give the structure and the IUPAC name for this alkane.

Give the best product for the reaction.

Which of the following does not occur in a propagation step in the free radical bromination of ethane to form bromoethane?

When petroleum is distilled, the fraction that contains compounds with 5 to 11 carbons is known as ________.

Identify as initiation, propagation, or termination.

Why are alkanes so unreactive?

Show the propagating steps in the addition of HBr to 1-pentene in the presence of peroxide.

Give the best product for the reaction.

When (R)-2-chlorobutane reacts with Br2/hv, which of the following is true?

The reaction Br2 + CH3Br → CH2Br2 + HBr was carried out. Which of the following mechanism steps is productive, but relatively unlikely to occur?

Provide the major organic product of the following reactions.

When (R)-2-bromobutane reacts with Cl2/hv, which of the following is true? I II

Rank the following fractions which result from the fractional distillation of petroleum in order of increasing boiling point: asphalt, gasoline, kerosene, natural gas, heating oil.

Which of the following is the most stable radical?

Which of the following products result from the disproportionation reaction between two propyl radicals?

When Br ∙ reacts with 1-butene (CH3CH2CH CH2), the hydrogen atom which is preferentially abstracted is the one which produces a resonance stabilized radical. Draw the major resonance contributing forms of this radical.

Which of the following is true about the halogenation of methane, CH4?

The reaction Br2 + CH3Br → CH2Br2 + HBr was carried out. Which of the following mechanism steps is both productive and relatively likely to occur?

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

Organometallic Compounds

Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

Catalysis

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters

An alkane with the molecular formula C₅H₁₀ forms only one monochlorinated product when heated with Cl₂/hv. Give the structure and the IUPAC name for this alkane.

When (R)-2-chlorobutane reacts with Br₂/hv, which of the following is true?

The reaction Br₂ + CH₃Br → CH₂Br₂ + HBr was carried out. Which of the following mechanism steps is productive, but relatively unlikely to occur?

When (R)-2-bromobutane reacts with Cl₂/hv, which of the following is true? I II

When Br ∙ reacts with 1-butene (CH₃CH₂CH CH₂), the hydrogen atom which is preferentially abstracted is the one which produces a resonance stabilized radical. Draw the major resonance contributing forms of this radical.

Which of the following is true about the halogenation of methane, CH₄?

The reaction Br₂ + CH₃Br → CH₂Br₂ + HBr was carried out. Which of the following mechanism steps is both productive and relatively likely to occur?