An example is the partial molar enthalpy Hi of a constituent of an ideal gas mixture, an ideal condensed-phase mixture, or an ideal-dilute solution. In these ideal mixtures. Hi is independent of composition at constant T and p (Secs. 9.3.3, 9.4.3, and 9.4.7). When a reaction takes place at eonstant T and p in one of these mixtures, the molar differential reaction enthalpy H is eonstant during the proeess, H is a linear function of and Af// and Ai7m(rxn) are equal. Figure 11.6(a) illustrates this linear dependence for a reaction in an ideal gas mixture. [Pg.317]

Condensed phases of systems of category 1 may exhibit essentially ideal solution behavior, very nonideal behavior, or nearly complete immiscibility. An illustration of some of the complexities of behavior is given in Fig. IV-20, as described in the legend. [Pg.140]

Figure 14.1. Dependence of fugacities in the gas phase on the composition of the condensed phase for an ideal solution. |

Consider a problem, in which we are interested in the mass-dependent partitioning of a solute between an ideal gas phase and a condensed phase. The ratio of the densities in the two phases or the partition coefficient for species a is then [Pg.407]

A solution is a condensed phase of several components, which may be subject to strong intermolecular forces. Despite the fundamental differences between solutions and gases, some laws for solutions are analogous to those for gases. If the solution is sufficiently dilute, the osmotic pressure is described by an equation similar to that for an ideal gas, and ideal solutions are treated as a special case of ideal gas. [Pg.323]

This concept of an ideal solution is of value because it represents the simplest kind of condensed mixture that has any pretense to physical reality although most solutions are not ideal [by the definition in equation (31)], there exist some real mixtures which are ideal, and many other solutions approach ideal behavior as they become dilute. In most cases the constants a,- in equation (31) are empirically found to have little, if any, pressure dependence, oc a (r). When the gas in equilibrium with the condensed phase is ideal f = pi), equation (31) reduces to Raoult s law, Xi p,. [Pg.534]

Therefore we seek ways for computing conceptuals of condensed phases while avoiding the need for volumetric equations of state. One way to proceed is to choose as a basis, not the ideal gas, but some other ideality that is, in some sense, "doser" to condensed phases. By "closer" we mean that changes in composition more strongly affect properties than changes in pressure or density. The basis exploited in this chapter is the ideal solution. We still use difference measures and ratio measures, but they will now refer to deviations from an ideal solution, rather than deviations from an ideal gas. [Pg.184]

Solubility equilibria resemble the equilibria between volatile liquids (or solids) and their vapors in a closed container. In both cases, particles from a condensed phase tend to escape and spread through a larger, but limited, volume. In both cases, equilibrium is a dynamic compromise in which the rate of escape of particles from the condensed phase is equal to their rate of return. In a vaporization-condensation equilibrium, we assumed that the vapor above the condensed phase was an ideal gas. The analogous starting assumption for a dissolution-precipitation reaction is that the solution above the undissolved solid is an ideal solution. A solution in which sufficient solute has been dissolved to establish a dissolution-precipitation equilibrium between the solid substance and its dissolved form is called a saturated solution. [Pg.678]

Here/represents an intensive property value for the real mixture, and all three terms in (5.2.1) are at the same temperature T, pressure P, composition x, and phase. The excess properties provide a convenient way for measuring how a real mixture deviates from an ideal solution. In general, an excess property/ may be positive, negative, or zero. An ideal solution will have all excess properties equal to zero. Note that the value for depends on the choice of standard state used to define the ideal solution. Further note that the definition (5.2.1) is not restricted to any phase excess properties may be defined for solids, liquids, and gases, although they are most commonly used for condensed phases. [Pg.189]

© 2019 chempedia.info