Question

a) Explain the mechanism of chlorination of methane.
b) Write the electronic structure of :-
i) Propene ii) But-l-ene
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Answer 1

$\bold{a) CHLORINATION \: OF \: METHANE}$

Chlorination is the process in which the hydrogen atom of an alkane is replaced by chlorine atoms by subsitution reaction.

◼$CH_4 + Cl_2 \longrightarrow CH_3Cl + HCl$

(monochloromethane)

◼$CH_3Cl + Cl_2 \longrightarrow CH_2Cl_2 + HCl$

(dichloromethane)

◼$CH_2Cl_2 + Cl_2 \longrightarrow CHCl_3 + HCl$

(trichloromethane)

◼$CHCl_3 + Cl_2 \longrightarrow CCl_4+ HCl$

(tetrachloromethane)

b) Carbon have 4 electrons in outermost shell so it shares its electron to be stable like nearest noble gas neon , which is either shared by other carbon atoms or hydrogen atoms.

Hydrogen have 1 electron in outermost shell so to be stable like nearest noble gas heluim it wants 1 more electron which is shared by carbons in hydrocarbons.

(i)-Propene $C_3H_6$ is an alkene which have one double bond among two carbon atoms.

Carbon is tetra valent , it shares its two electrons with second carbon atom and rest by hydrogen atom with single bond, but the second carbon atom have a single bond with thirds carbon atom it have only one free bond which is completed by hydrogen , while third carbon atom have three bonds left that is also completed by hydrogen atom.(Refer to image 1)

(ii)- But -(1) -ene , $C_4H_8$ , is an alkene which have 4 carbon atoms and 8 hydrogen atoms which first and second atom having double bond . While other bond of carbon and other two carbons is filled by hydrogen.(Refer to image 2)