How do you account for the formation of ethane during chlorination of methane ?

Explanation

To account for the formation of ethane during the chlorination of methane, we can break down the process into three main steps: initiation, propagation, and termination.

### Step-by-Step Solution:

1. **Initiation**:
- The chlorination of methane begins with the initiation step, where chlorine molecules (Cl₂) undergo homolytic cleavage. This process is often initiated by heat or light (represented as hν).
- The result of this cleavage is the formation of two chlorine free radicals (Cl•).

**Hint**: Remember that homolytic cleavage splits a molecule into two radicals, which are highly reactive.

2. **Propagation**:
- In the propagation step, one of the chlorine radicals (Cl•) reacts with a methane molecule (CH₄). This reaction results in the formation of a methyl radical (CH₃•) and hydrogen chloride (HCl).
- The methyl radical (CH₃•) is also a reactive species and can further react with another chlorine molecule (Cl₂). This reaction produces chloromethane (CH₃Cl) and another chlorine radical (Cl•).

**Hint**: The propagation step involves a chain reaction where radicals continuously react to form new radicals.

3. **Termination**:
- The termination step occurs when two radicals combine to form stable products. In this case, two methyl radicals (CH₃•) can combine to form ethane (C₂H₆).
- Additionally, two chlorine radicals can combine to form Cl₂, or a methyl radical can react with a chlorine radical to form CH₃Cl.

**Hint**: Termination steps are where radicals combine to form stable molecules, effectively ending the chain reaction.

### Conclusion:
The formation of ethane during the chlorination of methane occurs primarily in the termination step when two methyl radicals combine. This process illustrates how free radical mechanisms can lead to the formation of different products, including ethane.