Question

The molecules of alkene family are represented by a general formula $C_n{H}_{2n}$. Answer the following:
(a) What do n and 2n signify?
(b) What is the name of alkene when n = 4?
(c) What is the molecular formula of alkene when n = 4?
(d) What is the molecular formula of the alkene if there are ten H atoms in it?
(e) What is the structural formula of the third member of the alkene family?
(f) Write the molecular formula of lower and higher homologous of an alkene which contains four carbon atoms.

Answer 1

(a) n signifies the number of carbon atoms and 2n signifies the number of hydrogen atoms.

(b) The name of alkene when n = 4 is Butene.

(c) The molecular formula of alkene when n = 4 is $C_4{H}_8$.

(d) The molecular formula of alkene when there is 10 H atom in it $C_5{H}_{10}$.

(e) The structural formula of the third member of the alkene, propene is
$\underset{\underset{H}{|}}{\stackrel{H}{\stackrel{|}{C}}}=\stackrel{H}{\stackrel{|}{C}}-\underset{\underset{H}{|}}{\stackrel{H}{\stackrel{|}{C}}}-H$

(f) Lower homologous of alkene which contains four carbons is $C_3{H}_6$.
The higher homologue of alkene which contains four carbons is $C_5{H}_{10}$.