# What is an homologous series?

Question.
What is an homologous series? Explain with an example

solution:
A family of organic compounds having the same functional group, similar chemical properties and the successive members of which differ by a $\mathrm{CH}_{2}$ group or 14 mass units.

e.g. $\mathrm{CH}_{3} \mathrm{OH}$ (methanol)

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ (ethanol)

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ (propanol)

They constitute homologous series of alcohols. Because they have same functional group, differ by $-\mathrm{CH}_{2} / 14$ mass unit and have similar chemical properties.

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