Compressibility isotherms of helium-nitrogen mixtures at 298.15 K and up to 10 kbar

The compressibility isotherms of three samples of He-N2 mixtures containing, respectively, 25,50 and 75 mol% helium have been measured at 298.15 K and at pressures between 2 and 10 kbar using a modified stepwise expansion method. The accuracy of the measurements is estimated to be better than 0.05% in the pressure, 0.1% in the density and 0.005 K in the temperature. The experimental p-ϱ data for the three mixtures as well as the pure components can be represented over the full pressure and composition range by an isothermal equation of state with a standard deviation of 0.3%.