A comparative study of thermal pressure coefficients of liquid alkali metals using equation of state and dense fluid theory

摘要

A simple analytical expression is derived to calculate the thermal pressure coefficients of liquid alkali metals. First, a modified linear isothermal regularity is applied to calculate the thermal pressure coefficients for caesium (Cs) and rubidium (Rb) in different thermodynamic states. The results obtained show that the calculated thermal pressure coefficients increase with increase in the density and decrease in the temperature. The extent of deviation between the calculated thermal pressure coefficients from the modified regularity and experimental values reduce remarkably with respect to those obtained from the primary isothermal regularity. Secondly, the thermal pressure coefficients are determined by the accurate dense fluid theory for a hard-sphere system. A comparative study of the predicted thermal pressure coefficients for both Cs and Rb shows that the results obtained by the isothermal regularity theory are closer to the experimental data with respect to the ones obtained from the statistical thermodynamic method.