Royal Society Publishing

Thermal Conductivities of Organic Vapours

J. D. Lambert , E. N. Staines , S. D. Woods


The variation of thermal conductivity with pressure has been investigated for a number of organic vapours at pressures between 50 and 700 mm. and at temperatures of 25, 66 and 85 degrees C. Acetaldehyde and acetonitrile show fairly large linear increases of thermal conductivity with rise in pressure, which diminish markedly as temperature rises. This is interpreted as being due to dimerization, and a quantitative treatment is given in terms of values of K$_{p}$ and $\Delta $H for the reversible dimerization process, which are derived from previous work on the second virial coefficients of these vapours. Ethyl chloride shows similar behaviour to a much smaller degree. Methyl alcohol and acetone show fairly large non-linear increases, which diminish at higher temperatures, and which are interpreted as being due to association to polymers higher than the dimer. Benzene, cyclohexane, n-hexane, chloroform and diethyl ether, together with air and carbon dioxide, all show comparatively small linear increases, which become larger as temperature rises. No satisfactory quantitative explanation was found for this effect, which appears to involve factors other than simple convection. Values of the absolute thermal conductivity, corrected to zero pressure, are given for all vapours investigated.