Chapter 12, Problem 12.1YT

Interpretation Introduction

Interpretation: The given compound having the higher boiling point is to be identified.

Concept Introduction:

A hydrocarbon is organic compound consisting entirely of hydrogen and carbon.

The temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere is called boiling point.

The boiling point of a molecule depends upon intermolecular forces and thermal energy.

Intermolecular forces keep the molecules together. Greater the intermolecular force, higher is the boiling point.

All atoms and molecules possess dispersion forces which depend upon their molar mass.

Polar molecules possess dipole forces between them which depend upon the polarity of the molecules.

A molecular formula consists of the chemical symbols for the constituent elements followed by numeric subscripts describing the number of atoms of each element present in the molecule.

Dispersion forces are weak intermolecular forces and are considered van der waals forces.

Temporary dipoles can occur in non-polar molecules when the electrons that constantly orbit the nucleus occupy a similar location by chance.

Higher the molar mass, higher is the magnitude of the dispersion forces, and hence, higher is the boiling point.

Answer to Problem 12.1YT

Solution: ${\text{C}}_{10}{\text{H}}_{{}_{22}}$

Explanation of Solution

The boiling point of a molecule depends upon the intermolecular forces and the thermal energy. Intermolecular forces depend upon dispersion forces and dipole forces. The molecules, ${\text{C}}_8{\text{H}}_{18}$ and ${\text{C}}_{10}{\text{H}}_{{}_{22}}$ are alkanes and possesses dispersion forces which depends upon their molar mass. Higher the molar mass, higher is the magnitude of the dispersion forces, and hence, higher is the boiling point.

Since the molar mass of ${\text{C}}_{10}{\text{H}}_{{}_{22}}$ is higher than that of ${\text{C}}_8{\text{H}}_{18}$, therefore, the boiling point is higher for ${\text{C}}_{10}{\text{H}}_{{}_{22}}$.

Conclusion

The boiling point of ${\text{C}}_{10}{\text{H}}_{{}_{22}}$ is more than that of ${\text{C}}_8{\text{H}}_{18}$.