Question

.lWhat is meant by homologous series of organic compounds? Write the chemical formulae of two members of a homologous series and state which part determines the :( i ) physical properties, ( ii ) chemical properties, of these compounds.

Answer 1

homologous series is continuous series in which each step has the difference of CH2 .

two members are - alkanes - CnH2n+2
alkene - CnH2n.

Answer 2

Homologous Series is defined as a series of hydrocarbon compounds in which same functional group subtitutes for hydrogen. The succesive members of any homologous series differ by CH2 or 14u.

Chemical formula of two members of a homologous series contaning functional group alcohol are:-

Methanol-CH3OH

Ethanol-C2H5OH

1) Part determining Physical property is the hydrocarbon part i.e., CH3 and C2H5

2) Part determining chemical property is the functional group part i.e., OH.