The given chemical reaction involves the conversion of two molecules of chloromethane (CH4Cl) into ethane (C2H6), ethylene (C2H4), and then back into ethane (C2H6), followed by combustion to form carbon dioxide (CO2).

Overall reaction:
2 CH4Cl -> C2H6 + C2H4 -> C2H6 + CO2

Here is the breakdown of the reaction steps:

Step 1: CH4Cl -> C2H6 + C2H4
One molecule of chloromethane (CH4Cl) is converted into one molecule of ethane (C2H6) and one molecule of ethylene (C2H4).

Step 2: C2H4 + C2H6 -> C2H6
The ethylene (C2H4) reacts with ethane (C2H6) to form ethane (C2H6) only.

Step 3: C2H6 (ethane) + O2 -> CO2 + H2O
The final step involves combustion of ethane (C2H6) to form carbon dioxide (CO2) and water (H2O).