Chapter 1, Problem 1.44E

Interpretation Introduction

(a)

Interpretation:

The Van der Waals constant b can be used to estimate molecular sizes, assuming the molecules are shaped like spheres: b is to be converted to units of m³ / mol for He, molecular contribution and radius of He is to be calculated.

Concept introduction:

Prevalently, the ideal gas law is considered the molecules of a gas as point particles with perfectly elastic collisions among them in nature. In many experimental calculations, the ideal gas concept works importantly well for gases at dilution and at low pressure, but the gas molecules are not performing as point masses, and there are situations where the properties of the gas molecules have measurable effect by experiments. Thus, a modification of the ideal gas equation was coined by Johannes D. Van der Waals in 1873 to consider size of molecules and the interaction forces among them. It is generally denoted as the Van der Waals equation of state.