Thermodynamic properties of a mixture of He and N2 at high pressures determined from speeds of sound

The equation of state and heat capacity of a mixture of He and N2 of equal composition have been determined at temperatures from 156.15 to 298.15 K and at pressures from 200 to 1000 MPa using a recently developed computational method. This is based on stepwise construction of ϱT isobars starting from an experimental reference pϱ isotherm and using the previously reported sound speed data of the mixture as a function of pressure and temperature. The derived pϱT data have been fitted to a new empirical equation of state for the mixture with a r.m.s. deviation of 0.02%.