Effect of Argon and Helium on the Thermal Conductivity of the N2O4⇄2NO2 System

The effect of dilution by argon and by helium on the thermal conductivity of the dissociating N2O4⇄2NO2 system was investigated in a hot-wire apparatus. Values of the conductivity were obtained over a pressure range of 0.05 to 1.0 atmosphere at 300°, 320°, and 350°K, (the temperature range where the contribution of the reaction to the conductivity is large). Rigorous calculations of the conductivity were made for the three-component systems. Agreement between experimental and calculated values is generally good. At reduced pressures, experimental results are smaller than the calculated values. A calculation involving reaction rates is shown to predict these low-pressure effects.