The carbon-dioxide—nitrous-oxide system in the critical region

Abstract

The phase boundaries, orthobaric densities and critical constants of five mixtures of carbon dioxide and nitrous oxide have been measured between 20° C and the critical point. The same physical properties for the two pure gases have also been measured. The apparatus consisted of a calibrated thick-walled hard-glass pressure tube, fitted with an electromagnetic stirrer, for visual observation of the dew-points, boiling-points and critical points, plus auxiliary equipment for precise temperature and pressure measurements. The results, which show the system to be almost ideal with small positive deviations from Raoult’s law, are interpreted satisfactorily by the theory of conformal solutions. The results also agree with other experimental data on the transport properties of carbon-dioxide—nitrous-oxide mixtures, and with measurements of the isothermal expansion coefficients of such mixtures, but not with a previous investigation of the phase behaviour of the system.