(a) Propose a mechanism for the free-radical chlorination of ethane,
(b) Calculate for each step in this reaction.
(c) Calculate the overall value of for this reaction.
The overall reaction for the chlorination of ethane is as follows:
-+ -- CI + HCI
The free-radical mechanism for the chlorination of ethane follows three steps. They are as follows:
Molecular chlorine in the presence of light produces two chlorine free radicals.
It involves two steps.
Step I: One of the chlorine free radical reacts with ethane to produce ethyl radical.
-+ CI -+ HCI
Step II: The ethyl radical reacts with molecular chlorine to produce the product and the chlorine free radical.
-+ -CI + CI
The propagation steps continue to repeat until the reactants are exhausted and hence occur as a chain reaction.
The formula to calculate the enthalpy of each step in the reaction is as follows:
For the initiation reaction,
CI-CI : 242 kJ/mol
No bonds are formed in the initiation step.