Index of content:
Volume 25, Issue 2, March 1996
25(1996); http://dx.doi.org/10.1063/1.555992View Description Hide Description
The thermodynamic and spectroscopic properties of the oxygen fluoride species have been reviewed. Recommended thermochemical tables are given for five gaseous oxygen fluorides: OF, OFO, FOO, FOF, and O2F2. Sufficient information is not available to generate thermochemical tables for any condensed phase species. Annotated bibliographies (over 600 references) are provided for all neutral oxygen fluorides which have been reported in the literature. There are needs for additional experimental and theoretical data to reduce the uncertainties in the recommended values for these five species. Of all the species mentioned in the literature, many have not been isolated and characterized. In fact, some do not exist. Throughout this paper, uncertainties attached to recommended values correspond to the uncertainty interval, equal to twice the standard deviation of the mean.
A Modified Benedict–Webb–Rubin Equation of State for the Thermodynamic Properties of R152a (1,1‐difluoroethane)25(1996); http://dx.doi.org/10.1063/1.555979View Description Hide Description
A modified Benedict–Webb–Rubin (MBWR) equation of state has been developed for R152a (1,1‐difluoroethane). The correlation is based on a selection of available experimental thermodynamic property data. Single‐phase pressure–volume–temperature (PVT), heat capacity, and sound speed data, as well as second virial coefficient, vapor pressure, and saturated liquid and saturated vapor density data, were used with multi‐property linear least‐squares fitting to determine the 32 adjustable coefficients of the MBWR equation. Ancillary equations representing the vapor pressure, saturated liquid and saturated vapor densities, and the ideal gas heat capacity were determined. Coefficients for the equation of state and the ancillary equations are given. Experimental data used in this work covered temperatures from 162 K to 453 K and pressures to 35 MPa. The MBWR equation established in this work may be used to predict thermodynamic properties of R152a from the triple‐point temperature of 154.56 K to 500 K and for pressures up to 60 MPa except in the immediate vicinity of the critical point.
Liquid–Liquid Demixing from Solutions of Polystyrene. 1. A Review. 2. Improved Correlation with Solvent Properties25(1996); http://dx.doi.org/10.1063/1.555980View Description Hide Description
Low pressure liquid–liquid demixing data for polystyrene dissolved in 76 different one‐component solvent systems are reviewed and correlated. The phase diagrams are discussed. With only one exception the molecular weight of each solvent is less than that of two polystyrene monomer units. A new relation is developed which quantitatively correlates the area of solubility lying between the UCS and LCS demixing curves in the (T c, M w −1/2) projection with solventsolubility parameters.
Volumetric Properties of Single Aqueous Electrolytes from Zero to Saturation Concentration at 298.15 °K Represented by Pitzer’s Ion‐Interaction Equations25(1996); http://dx.doi.org/10.1063/1.555981View Description Hide Description
The ion interaction approach developed by Pitzer allows the prediction of various thermodynamiccharacteristics of multiple‐solute electrolyte solutions, if the respective parameters for each type of single‐solute electrolyte solution are known. The present paper discusses the Pitzer approach to the calculations of the volumetric properties of single‐solute electrolyte solutions. The databases for the densities and the apparent molal volumes versus concentrations were created at 298.15 °K using essentially all published relevant data for each single‐solute electrolyte solution. Poor experimental data were discarded by a statistical treatment applied to these databases. Proper treatment of all good quality density and apparent molal volume data, in a wide range of concentrations from infinite dilution through saturation, allowed us to evaluate the volumetric ion interaction parameters (V̄0 MX, βMX (0)V , βMX (1)V , βMX (2)V , and C MX V ) at 298.15 °K for 102 electrolytes. Strong linear relationships between the βMX (1)V , βMX (2)V , or C MX V , and βMX (0)V volumetric ion interaction parameters were observed for all analyzedsolutes with slopes depending on the solute valency types.