Liquid solutions pressure—volume—temperature relationship

The Chao-Seader and the Grayson-Streed methods are very similar in that they both use the same mathematical models for each phase. For the vapor, the Redlich-Kwong equation of state is used. This two-parameter generalized pressure-volume-temperature (P-V-T) expression is very convenient because only the critical constants of the mixture components are required for applications. For the liquid phase, both methods used the regular solution theory of Scatchard and Hildebrand (26) for the activity coefficient plus an empirical relationship for the reference liquid fugacity coefficient. Chao-Seader and Grayson-Streed derived different constants for these two liquid equations, however. 

If a gas phase is present, chemical species may volatilize from the liquid or solid phase, which is an important partitioning process in a variety of circumstances (e.g., transport in the unsaturated zone, or for treatment processes). The equilibrium vapor pressure can be used with the ideal gas law to estimate the mass in a given volume and temperature under equilibrium conditions. For solutions with more than one component, Raoult s law can be used to quantify the vapor pressure of each component. For dilute aqueous solutions, Henry s law describes the equilibrium relationship between dissolved chemicals and their vapor pressure ... 

Henry s law The law states that the amount of a gas that dissolves in a given volume of a liquid at constant temperature is directly proportional to the pressure the gas exerts above the liquid. The Henry s law constant, H, reflects the relationship between gas phase over a solution and dissolved species. Hence, Henry s law can be used to calculate the amount of gas present at saturation at any temperature. 

Thermodynamic properties are characteristics of a system (e.g., pressure, temperature, density, specific volume, enthalpy, entropy, etc.). Because properties depend only on the state of a system, they are said to be path independent (unlike heat and work). Extensive properties are mass dependent (e.g., total system energy and system mass), whereas intensive properties are independent of mass (e.g., temperature and pressure). Specific properties are intensive properties that represent extensive properties divided by the system mass, for example, specific enthalpy is enthalpy per unit mass, h = H/m. In order to apply thermodynamic balance equations, it is necessary to develop thermodynamic property relationships. Properties of certain idealized substances (incompressible liquids and ideal gases with constant specific heats) can be calculated with simple equations of state however, in general, properties require the use of tabulated data or computer solutions of generalized equations of state. 

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