Vapor Pressures, Critical Parameters, Boiling Points, and Triple Points of Ammonia and Trideuteroammonia

A simple extended corresponding-states principle is used to represent the vapor pressure of ammonia and trideuteroammonia from the triple point to critical point and to describe the available experimental data along with extrapolation beyond their ranges of available experimental data. This work takes advantage of the adoption of the ITS-90 temperature scale and of the new critical parameters obtained from the extended corresponding-states principle. The vapor pressure data are described within their scatter in the entire temperature range. Comparisons with the available data show that the extended corresponding-states principle may calculate the vapor-pressure values within 0.05%–0.1% The substance-dependent characteristic parameters are given, such as critical temperature, critical density, critical pressure, acentric factor, and aspherical factor. The values of the pressures, along with their first and second derivatives as a function of temperature over the entire region from the triple point to the critical point are tabulated and recommended for scientific and practical uses.