Chapter 21.3, Problem 23SSC

Interpretation Introduction

Interpretation:

The comparison of boiling and freezing points of alkyne with those of alkanes having same number of carbon atoms 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 whereashydrocarbon 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 triple bonds are said to be alkyne. Compared to alkanes, alkynes have slightly higher boiling and freezing pointsdue to presence of pi-bonds in alkynes which increases the electron density on carbon atoms.

For example: the boiling point of butane and butyne is ${\text{-1 }}^{\text{o}}\text{C and 8}{\text{.08 }}^{\text{o}}\text{C}$ respectively. And the trend is same in freezing points as, butane and butyne freezes at ${\text{-138 }}^{\text{o}}\text{C and -125}{\text{.7 }}^{\text{o}}\text{C}$ respectively.