Temperature dependence of the binary diffusion coefficient of gases

The variation with temperature of the binary gas diffusion coefficient for the gas pairs N 2 ‐ H 2 and NH 3 ‐ H 2 is reported for the temperature range of 0°–300°C. The data were obtained using a steady state flow method, and the apparatus and experimental conditions relative to this technique are discussed. Although this method does not give absolute values of the diffusion coefficient, it is relatively simple and accurate. The extent of agreement of the data with equations for the prediction of gas diffusion coefficients is shown. Better results are obtained when these equations are applied to nearly ideal systems, such as the N 2 ‐ H 2 pair, rather than to gases which have highly polar molecules such as NH 3 .