Thermal conductivity of simple gases at normal pressures

Thermal conductivity measurements available in the literature for simple gases at normal pressures (approximately 1 atmosphere) were used to obtain the product k * λ, where the parameter, λ = M 1/2 T c 1/6 /P c 2/3 . Separate relationships between k * λ and T R resulted for monatomic, diatomic and triatomic gases. The relationships for monatomic gases can be expressed as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_m = 9.96 \times 10^{ - 5} \left[ {e^{0.046T} R - \frac{1}{{e^{0.046T} R}}} \right] $$\end{document}For the diatomic and triatomic gases, linear relationships resulted, when at the same reduced temperatures, their k * λ values were plotted against ( k * λ) m on log‐log coordinates. These relationships can be expressed in equation form as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_d = 1.105\left( {k*\lambda } \right)_m ^{1.10} \quad \left( {{\rm diatomic}\,{\rm gases}} \right) $$\end{document}and\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_t = 1.02\left( {k*\lambda } \right)_m ^{1.46} \quad \left( {{\rm triatomic}\,{\rm gases}} \right) $$\end{document}Thermal conductivities calculated with these relationships have been compared with experimental values and produce an average deviation of 2.8% for the monatomic gases (219 points), 4.3% for the diatomic gases (282 points) and 4.6% for the triatomic gases (242 points). In this treatment, helium and hydrogen do not follow the general pattern and consequently these substances have been treated separately.