The Vapor Pressures and Critical Constants of Pure Ozone

Vapor pressures of pure ozone have been measured over the range −183°C to −30°C with an estimated accuracy of ±3 percent and are represented by the equation $$\log P_{\mathrm{mm}}\text{=8.25313−}\frac{\text{814.941587}}{T}\text{−0.001966943T.}$$ The normal boiling point is −111.9°C±0.3°C. The critical temperature has been determined experimentally and found to be −12.1°C±0.1°C. The critical pressure derived from this critical temperature and the vapor pressure equation is 54.6 atmospheres absolute. Results are, in general, in good agreement with the meager data in the literature. The precision of the vapor pressure data is limited by the unstable nature of ozone and the necessarily small samples which must be used for measurements in the interests in the interests of safety.