Chapter 21, Problem 59A

Interpretation Introduction

Interpretation:

The difference of alkenes from alkanes and of alkynes from both alkenes and alkanes needs to be explained.

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms.

Explanation of Solution

The hydrocarbon compounds that contains single bond(s) between carbon atom(s) are said to be saturated hydrocarbon whereas hydrocarbon compounds that contains multiple bond(s) between carbon atom(s) are said to be unsaturated hydrocarbon. Compounds containing single bonds are said to be alkane and compounds containing double bonds are said to be alkene whereas compounds containing triple bonds are said to be alkyne.

The general formula of:

Alkane is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$ .

Alkene is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$ .

Alkyne is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$ .

The number of H atoms in alkene is 2 units less than that in alkane and the number of H atoms in alkyne is 2 units less than that in alkene and 4 units less than that in alkane.

For example:

The molecular formula of propane is ${\text{C}}_3{\text{H}}_{\text{8}}$.

The molecular formula of propene is ${\text{C}}_3{\text{H}}_6$.

The molecular formula of propyne is ${\text{C}}_3{\text{H}}_4$.