An Advanced Platform for Thermodynamics Education. Part one: Small Density Pure Real Gases

Abstract

The paper presents an advanced platform for thermodynamics education - the equilibrium pure real gas system, which has been deeply investigated experimentally and theoretically by researchers from all over the World. But in spite of a huge amount of extra precise experimental data, the nature of real gases and clusters in them is still poorly understood. The clusters are considered now as a new state of matter. To study them is both challenging and educative. We use a wonderful feature of pure real gases: the chemical potential for all basic particles in a gas is universal for all clusters. It permits us to find the monomer fraction density Dm from an experimental pressure dependence of the total density. This variable has proven to be the key to properties of clusters and molecular interactions. The advanced platform is more informative for thermodynamics education than the widely used ideal gas model, which ignores molecular interactions. It provides a new vision of molecular interactions in clusters, the entropy and Joule-Thomson effect in pure real gases, gas-to-liquid transition in supercritical fluids. Moving step-by-step from ideal to denser gases students understand better the complex nature of condensation. Here we start from small density gases.