4.1.2 - Alkanes

Question 1

The first step in the reaction mechanism involves homolytic fission of a chlorine molecule to form two chlorine radicals. Why is this step an example of homolytic fission? (1)

Answer 1

• One electron from the bond (pair) goes to each atom / chlorine/radical

Question 2

At room temperature and pressure, the first four members of the alkanes are all gases but the first four alcohols are all liquids. Explain this difference in terms of intermolecular forces. (2)

Answer 2

• Alcohols have hydrogen bonds (and London forces)
• Hydrogen bonds are stronger London forces (in alkanes

Question 3

Describe how a σ-bond forms. (1)

Answer 3

• Overlap of orbitals directly between the bonding atoms

Question 4

Radical substitution produces a mixture of organic products. (2)

Answer 4

• Further substitution / produces different termination products / more than one termination step
• Substitution at different positions along chain