Pressure dependence of the mutual diffusion coefficients of the binary systems N2 + Ar, N2 + O2, O2 + Ar and Ar + Kr at 300 and 323 K

The Loschmidt technique has been used to measure the pressure dependence at two temperatures of the binary diffusion coefficients of the systems N2-Ar, N2-O2, O2-Ar and Ar-Kr; gas mixtures were analysed with a mass spectrometer. The results for the first three systems indicate that the first term of the Thorne-Enskog theory for moderately dense gases is not adequate to describe binary diffusion in these systems. Because the quantity (nD12) is a linear function of the number density in all cases, higher order terms need not be considered.