Implications of standard states and ideal solution in terms of Raoult's law

Traditionally, Raoult's law has always been considered to describe the vapor‐liquid equilibrium of ideal solutions. This treatment not only is awkward but also is not in complete agreement with the definition of an ideal solution in the sense of the Lewis‐Randall rule. In this study, the characteristics of a model system of Raoult's law are analyzed. The analysis is based on the application of the Lewis‐Randall rule in which the actual states of the pure components are used as the standard states. It is shown that, in the region where vapor‐liquid equilibrium exists, neither the vapor nor the liquid is an ideal solution in the strict sense of the Lewis‐Randall rule.