On the Relation between Total and Partial Pressure of Gas Mixture

Abstract

It may be inadequate, in general, to apply Dalton's law to an imperfect gas mixture. In this paper, the total pressure of an imperfect gas mixture is considered from the view point of statistical mechanics. Namely, by expressing the equation of state in the virial expansion form, the total pressure of a gas mixture was determined analytically by using the second and the third virial coefficients calculated from the values for each component gas. For one example, the second and third virial coefficients of air were calculated by two methods and compared with each other as well as with other values which were determined directly from experimental data with air. From the numerical calculations for air and also for water-mercury vapour mixture, it has been made clear that there is some difference between the total pressure calculated by our methods and the value calculated from Dalton's law, and this difference increases with the degree of imperfectness of the gas mixture.