Question

Write the names and formulas of the products formed when methane reacts with chlorine. Write the chemical equations.

Answer 1

Methane reacts with chlorine in diffused sunlight, or when heated to 600 K, to give chloromethane.

\[\ce{CH4 + Cl2 ->[diffused sunlight][or 600 K] CH3Cl + HCl}\]

OR

\[\begin{array}{cc}
\ce{H}\phantom{....................}\ce{H}\phantom{.......}\\
|\phantom{.....................}|\phantom{.......}\\
\ce{H - C - H + Cl2 -> H - C - Cl + HCl}\\
|\phantom{.....................}|\phantom{.......}\\
\ce{\underset{Methane}{H}}\phantom{.............}\ce{\underset{Chloromethane}{H}}\phantom{.....}\\
\end{array}\]

In this reaction, CH₃Cl is formed by the substitution of a hydrogen atom of a methane molecule by a chlorine atom. This type of reaction is known as a substitution reaction and the product formed is known as a substitution product.

The product formed (chloromethane) further reacts with chlorine, substituting one more hydrogen atom and producing dichloromethane. This further produces trichloromethane and finally, tetrachloromethane.

\[\ce{\underset{Chloromethane}{CH3Cl} + Cl2 -> \underset{Dichloromethane}{CH2Cl2} + HCl}\]

\[\ce{\underset{Dichloromethane}{CH2Cl2} + Cl2 -> \underset{(Chloroform)}{\underset{Trichloromethane}{CHCl3}} + HCl}\]

\[\ce{\underset{Trichloromethane}{CHCl3} + Cl2 -> \underset{(Carbon tetrachloride)}{\underset{Tetrachloromethane}{CCl4}} + HCl}\]