Thermal Conductivities of Ordinary and Isotopically Substituted Polar Gases and Their Equimolar Mixtures

Abstract

Thermal-conductivity measurements have been carried out over the temperature range 300° to 475°K with an eight-cell hot-wire thermal-conductivity apparatus. The thermal conductivities of the deuterated gases are greater than those of their unsubstituted counterparts at the higher temperatures (presumably because of their higher heat capacities). Conductivities of the equimolar mixtures lie about midway between the conductivities of the pure components. Results are analyzed to test a recent hypothesis that a resonant exchange of rotational quanta causes the thermal conductivity of a polar gas to seem anomalously low in relation to its viscosity. These results are consistent with this hypothesis, the only qualification being that near-resonant exchange is also important.