(a) What is meant by a substitution reaction? Give an example (with equation) of the substitution reaction of an alkane.

(b) How is soap made? Write a word equation involved in soap making.

(a) Substitution reaction occurs when hydrogen atoms of a hydrocarbon are substituted by other atoms. It is a characteristic of saturated hydrocarbons (alkanes).
Example: Methane (alkane) reacts with chlorine, in the presence of sunlight, to form chloromethane and hydrochloric acid.
The chemical equation for the reaction is given below:
$CH_4 + Cl_2 \xrightarrow{sunlight} CH_3Cl + HCl$

(b) Soap is prepared by heating animal fat or vegetable oil (esters) with concentrated sodium hydroxide solution.
Saponification is the process of preparing soap by the hydrolysis of fats with alkalis. 
The equation involved in soap making is given below:
Fat or oil (Ester) + Sodium Hydroxide → Soap (Sodium salt of fatty acid) + Glycerol (alcohol)


Simply Easy Learning

Updated on: 10-Oct-2022


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