Question 1

Which type of reaction is described when an alkane reacts with Cl$$_2 or Br$_2 in $$the presence of heat or UV light to form an alkyl halide and HX?

Accepted Answer

Halogenation

Question 2

In the halogenation of alkanes, what is the role of heat or UV light?

Accepted Answer

To break the bond between halogen atoms, forming free radicals

Question 3

During the halogenation of propane with Cl$$_2$$ and heat, which major product is expected from monosubstitution?

Accepted Answer

2-chloropropane

Question 4

Which statement best describes a mono-substituted alkane?

Accepted Answer

Only one hydrogen atom is replaced by a halogen atom

Question 5

What is the balanced chemical equation for the halogenation of ethane with Br$$_2$$ under heat, assuming monosubstitution?

Accepted Answer

$$\mathrm{C_2H_6 + Br_2$ \xrightarrow{heat} C_2H_5Br + HBr}$$

Question 6

Which of the following is a common misconception about alkane halogenation reactions?

Accepted Answer

Halogenation can occur without breaking the halogen-halogen bond

Question 7

If butane undergoes monosubstitution with Cl$$_2$$ and heat, which of the following is NOT a possible major product?

Accepted Answer

3-chlorobutane

Question 8

Why are secondary hydrogens more likely to be substituted than primary hydrogens in alkane halogenation?

Accepted Answer

Secondary radicals formed are more stable than primary radicals

Question 9

Which of the following best describes the products of the reaction: 2-methylpropane + Br$$_2 ($$heat)? Assume monosubstitution.

Accepted Answer

2-bromo-2-methylpropane

Question 10

A student mixes pentane with Cl$$_2$$ and exposes the mixture to UV light. Which of the following is the most likely major product?

Accepted Answer

2-chloropentane

Question 11

Which equation correctly represents the halogenation of methane with Cl$$_2$$ under UV light?

Accepted Answer

$$\mathrm{CH_4$ + Cl_2$ \xrightarrow{UV} CH_3Cl + HCl}$$

Question 12

Which of the following statements is TRUE regarding alkane halogenation?

Accepted Answer

Halogenation of alkanes is a substitution reaction

Question 13

In the halogenation of alkanes, what is the function of the halogen molecule (X$$_2$$)?

Accepted Answer

It provides the halogen atom that substitutes for a hydrogen atom

Question 14

Which of the following is a product of the reaction: isobutane + Cl$$_2 ($$heat)? Assume monosubstitution.

Accepted Answer

2-chloro-2-methylpropane

Question 15

Which of the following is required to initiate the halogenation of alkanes?

Accepted Answer

Heat or UV light

Question 16

What is the major product when 2,2-dimethylpropane reacts with Br$$_2$$ under heat, assuming monosubstitution?

Accepted Answer

No reaction occurs

Question 17

Which of the following best explains why tertiary hydrogens are most reactive in alkane halogenation?

Accepted Answer

Tertiary radicals are more stable due to hyperconjugation and inductive effects

Question 18

Which of the following is NOT a product of the halogenation of propane with Cl$$_2$$ and heat?

Accepted Answer

Propene

Question 19

A patient accidentally inhales chlorine gas. Which chemical reaction could occur in the lungs if the patient has alkanes present in their respiratory tract?

Accepted Answer

Alkane halogenation, producing alkyl chlorides and HCl

Alkane Halogenation Reactions: Mechanism and Products

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