Question

Write the molecular formula of two consecutive members of homologous series of aldehydes. State which part of these compounds determines their

1. physical and 
2. chemical properties

Write the molecular formula of any two consecutive members of homologous series of aldehydes.

Answer 1

The molecular formula of two consecutive members of homologous series of aldehydes:-

\[\ce{CH3 - CHO}\] and \[\ce{CH3 - CH2 - CHO}\]

In \[\ce{CH3 - CHO}\] compound, \[\ce{-CHO}\] part and in \[\ce{CH3 - CH2 - CHO}\], \[\ce{-CH2-CHO}\] part will determine their physical and chemical properties.

Answer 2

Two consecutive members:

	Molecular Formula	Structure
Methanal (Formaldehyde)	\[\ce{CH2O}\]	\[\ce{H - CHO}\]
Ethanal (Acetaldehyde)	\[\ce{C2H4O}\]	\[\ce{CH3 - CHO}\]