Write one chemical equation to represent each of the following types of reactions of organic substances:

(i) Esterification

(ii) Saponification

(iii) Substitution

The chemical equations representing the three types of organic reactions are:

(i) Esterification Reaction:

When ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst, a sweet-smelling substance called an ester (ethyl ethanoate) is formed:

$$\text{CH}_3 ext{COOH} + \text{CH}_3 ext{CH}_2 ext{OH} \xrightarrow{\text{Acid}} \text{CH}_3 ext{COOCH}_2 ext{CH}_3 + \text{H}_2 ext{O}$$

(ii) Saponification Reaction:

On treating an ester with an alkali like sodium hydroxide, it is converted back into alcohol and the sodium salt of the carboxylic acid. This reaction is used in the preparation of soap:

$$\text{CH}_3 ext{COOCH}_2 ext{CH}_3 + \text{NaOH} \rightarrow \text{CH}_3 ext{COONa} + \text{CH}_3 ext{CH}_2 ext{OH}$$

(iii) Substitution Reaction:

Saturated hydrocarbons undergo substitution reactions with chlorine in the presence of sunlight, where chlorine atoms replace hydrogen atoms one by one:

$$\text{CH}_4 + \text{Cl}_2 \xrightarrow{\text{Sunlight}} \text{CH}_3 ext{Cl} + \text{HCl}$$