This paper reports measurements made for DIPPR Research Project 821 in
the 1994 Project Year. Vapor
pressures were measured to a pressure limit of 270 kPa or lower
decomposition point for eight compounds
using a twin ebulliometric apparatus. Liquid-phase densities along
the saturation line were measured
for each compound over a range of temperatures (ambient to a maximum of
548 K). A differential scanning
calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat
capacities for each compound in
the temperature region ambient to the critical temperature or lower
decomposition point. Where possible,
the critical temperature and critical density for each compound were
determined experimentally. The
results of the measurements were combined to derive a series of
thermophysical properties including
critical temperature, critical density, critical pressure, acentric
factor, enthalpies of vaporization [within
the temperature range (±50 K) of the vapor pressures], enthalpies of
fusion if solid at ambient temperature,
solubility parameter, and heat capacities along the saturation line.
Wagner-type vapor-pressure equations
were derived for each compound. In addition, the liquid-phase
densities were compared with values
derived using a four-term power series in either T or
[(1 − T
r)1/3].
All measured and derived values were
compared with those obtained in a search of the literature.
Recommended critical parameters are listed
for each of the compounds studied. A “Rule-Of-Thumb” derived
in the 1992 Project Year was used to
estimate thermal decomposition temperatures by radical scission from a
knowledge of the bond dissociation
energy or vice versa.