Diffusion Coefficients of the Systems CO2–CO2 and CO2–N2O

Abstract

The radioactive tracer, C¹⁴O₂, has been used to measure diffusion coefficients for the systems CO₂–CO₂ and CO₂–N₂O in the temperature range −78° to 90°C. The apparatus, which is the Loschmidt type, uses saturation ionization currents as a measure of the extent of diffusion. The characteristics of this type of apparatus have been analyzed in detail to obtain working equations which permit use of experimental measurements at both small and large values of the time. The present results, whose accuracy is estimated at 1.5 percent, agree with those obtained by other investigators using different experimental methods. Although the difference is small, 2.6±0.3 percent, the diffusion coefficient for the system CO₂–N₂O is consistently larger than that for CO₂–CO₂ over the entire temperature range.