An equation of state for gases at low densities is developed, using a new function for the change in viscosity with temperature, also developed herein.The gas law equation takes the form[Formula: see text]or V(1 + KT)(PV − RT) = λT − a where a and b are constants corresponding to those of the Van der Waals' equation, and K is a constant derived from the proposed viscosity function which is, for carbon dioxide,[Formula: see text]where K is a constant and η is the viscosity at an absolute temperature T.In the case of carbon dioxide the equation was found to follow density results with an accuracy of from 0.01% to within experimental limits, and the viscosity function was found to agree with Sutherland's (10) results between −78.5 and 20 °C.Comparisons with several other equations of state are made. These show that the new equation is probably more accurate than any other.An expanded form of the new equation, namely:[Formula: see text]permits calculations of the slopes of isothermals for any temperature. Comparisons are made with experimental data.The expanded form of the equation may be solved for K, giving the expression:[Formula: see text]where [Formula: see text] and [Formula: see text] and ξ = Rb0, and since the equation enables the calculation of the molecular radius r, the viscosity may be calculated for any temperature and pressure over which the equation holds.
Modified Redlich-Kwong and Peng-Robinson Equations of State for Solubility Calculation of Solid Compounds in Supercritical Carbon dioxide
