Question

Machenism of reaction Ch4 + 4cl2 _ ccl4 + 4hcl

Answer 1

Answer:

Explanation:

When methane is mixed with chlorine in the presence of sunlight, a free radical substitution reaction occurs.

In the initiation step, Cl2 undergoes homolytic fission in sunlight to form Cl atoms, which have unpaired electrons thereby making them a very reactive species known as radicals.

Cl2 → 2Cl•

In the propagation steps,

1) the reactive Cl radical then collides with methane molecules to grab a H atom, forming HCl and a methyl radical.

CH4 + Cl• → •CH3 + HCl

2) the methyl radical seeks out a Cl2 molecule to form chloromethane(CH3Cl) and a Cl radical.

•CH3 + Cl2 → CH3Cl +Cl•

In the termination step,

1) The methyl radicals can come together to form ethane (CH3CH3)

•CH3 + •CH3 → CH3CH3

2) The methyl radical comes together with a chlorine radical to form chloromethane (CH3Cl)

•CH3 +Cl• → CH3Cl

3) The chlorine radicals come back together to reform Cl2.

Cl• + Cl• → Cl2

As seen from above, upon the completion of the first substitution, chloromethane (CH3Cl) is formed.

However due to the presence of Cl radicals and 3 H atoms still available for substitution on the chloromethane, it can undergo further substitution to form dichloromethane (CH2Cl2).

Following these steps, dichloromethane can then undergo a further substitution to give trichloromethane (CHCl3) or chloroform.

Lastly, trichloromethane can undergo yet another substitution to give tetrachloromethane.

As such, in the reaction vessel, we will find a mixture of mono, di, tri and tetrachloromethane.