. What is homologous series of carbon compounds? Write the molecular formula of two consecutive members of homologous series of aldehydes

State which part of the compounds determines their (r) physical and (it) chemical properties.


Best Answer

Ans. Homologous series. A series of carbon compounds in which the same functional group substitutes for hydrogen on a carbon chain is called a homologous series. There is a difference of -CH2 in the molecular formulae of two nearest compounds of a homologous series. Each such series has same general molecular formula and has a general scientific name. There is a difference of 14  (unified mass) in the molecular masses of nearest compounds of a series. Members of homologous series of aldehydes:

H – CHO Methanal

CH3 – CHO Ethanal

C2H5 – CHO Propanal

(i) The carbon-chain attached to aldehyde group, i.e., (H-, CH3 -, C2H5 -) determine the physical properties.

(ii) The functional group attached to all aldehydes (-CHO) determines the chemical properties.


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