Psychometry: From Partial Pressures to Mole Fractions

Abstract

This study uses the viria1 and interaction coefficients of the normal air components in deriving compressibility factors and thereafter a simple iterative formulation for mole fractions. Conversion from partial pressures to mole fractions now becomes tractable by means of determinate multipliers. The results obtained compare most favourab1y with the widely accepted derivations due to Goff and Gratch. One possible advantage is that the presented formulation permits the evaluation of those multipliers without reference to the virial and interaction coefficients provided that the "dry air" and moist air compressibility’s are very accurately measured. A possible simplification is that this partial pressure multiplier is expressed explicitly in a form suggesting acceptable results for air-water gaseous mixtures outside the range of normal air psychometry.