Problems and exercisesReactivity

1. Homolytic or heterolytic

State whether each cleavage is homolytic or heterolytic:

1. CH₄ → CH₃· + H·
2. HCl → H⁺ + Cl⁻
3. Cl₂ → 2 Cl·
4. H₂O → H⁺ + HO⁻

2. Why are they so unreactive?

The C–H bonds of propane (98 kcal/mol) are no stronger than the N–H bond of ammonia (107 kcal/mol). Why, then, are alkanes so unreactive?

3. The four typical reactions

Name the typical alkane reaction that corresponds to each transformation:

1. CH₃CH₂CH₂CH₃ → (CH₃)₃CH
2. CH₄ + Cl₂ → CH₃Cl + HCl
3. CH₃CH₃ → CH₂=CH₂ + H₂
4. CH₄ + 2 O₂ → CO₂ + 2 H₂O

4. Radicals and ions

Which species are formed in the homolytic cleavage of a bond? And in heterolytic cleavage?