Saturated Vapor Pressure Curve Research Articles

Specific conductivity and ionic product of water between 50 and 271 °C

The specific conductivity of high-purity water has been measured at temperatures between 51° and 271°C along the saturated vapour pressure curve. Correction has been made for traces of contamination. The frequency dispersion of the impedance of the water-filled cell has been analyzed in terms of an equivalent electrical circuit. The data have been used to calculate the ionic product constant of water over this temperature range.

Specific Conductivity of High-purity Water up to 300° C

THIS communication reports work in progress on the direct measurement of the conductivity of high purity water from 100 to 300° C along the saturated vapour pressure curve.

Phase equilibria of polymer‐solvent systems at high pressures near their critical loci: Polyethylene with n‐alkanes

AbstractAbove the crystallization temperature slightly branched polyethylene and propane are miscible in all proportions above a critical pressure, defined as upper critical solution pressure (UCSP). This pressure decreases only very slightly from 110 to 150°C. At 110°C. the UCSP varies from 450 atm. for a polymer fraction of molecular weight 17,000, to 580 atm. for one of molecular weight 250,000. The critical polymer concentrations are low as in conventional polymer‐solvent systems and shift with molecular weight in a similar manner. The pressures required to achieve solubility of the polymer in the gas at polymer concentrations less than critical (dew‐point pressures) are nearly as high as the UCSP down to very low polymer concentrations. The data determine part of the critical locus in (P, T, composition) space. Experiments with other polyethylene‐n‐alkane systems (ethane, butane, and pentane) show that the critical locus changes gradually from a liquid‐liquid to a gas‐liquid boundary and might be termed a fluid‐liquid locus. If crystallization of polymer does not intervene, this locus intersects the saturated vapor pressure curve at a lower critical end point (LCEP) which is the lower critical solution temperature (LCST) found only recently by Freeman and Rowlinson in many hydrocarbon polymers with hydrocarbon solvents. Incomplete miscibility extends over greater regions of temperature and pressure as the solvent molecule becomes smaller, but the critical locus would probably be closed along the pressure axis for a hypothetical amorphous polymethylene with ethane.

An electronic analogue of the saturated vapour pressure curve of water

An analogue of the saturated vapour pressure curve of water between 0 and 30° C which is suitable for inclusion in a complete electrical simulation of the psychrometric equation is described. The stated range of temperature can be covered in three sub-ranges of ten centigrade degrees, each with an accuracy in vapour pressure of a fraction of 1%. A theoretical analysis indicates that the slope of the curve, which is important in certain applications, is reproduced with 2% accuracy.