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]

We now proceed to calculate the thermodynamic functions of a condensed phase. First, by taking the temperature and pressure as independent variables, we may evaluate the molar enthalpy. [Pg.161]

Up to now, we considered that any solid was perfect and thus had a molar enthalpy of formation that depended only on the temperature. This approximation is justified in the study of the condensation of a gas or a liquid, because the variations of chemical potential according to the composition are much larger in the fluid phase, and in practice, they make negligible the same effects in the solid, ft is no more the case when one of the reactants is a solid, because in fact the defects in the solid constitute the reacting species. [Pg.266]

For component i of a condensed-phase mixture, we take a constant pressure equal to the standard pressure p°, and a mixture composition in the limit given by Eqs. 9.5.20-9.5.24 in which the activity coefficient is unity. Hi is then the standard molar enthalpy H , and the activity is given by an expression in Table 9.5 with the pressure factor and activity [Pg.367]

Apart from the inherent interest in the gas phase ion clusters, the accumulation of solvent molecules around an ion should yield at the limit of very large values of n to a constant value of j H°(S,g). This would be the molar enthalpy of condensation of a solvent molecule into the bulk liquid solvent, because at this limit, the ion has no influence any more on the energetics of the process. Thus [Pg.27]

Clausius-Clapeyron equation - An approximation to the Clapeyron equation applicable to liquid-gas and solid-gas equilibrium, in which one assumes an ideal gas with volume much greater than the condensed phase volume. For the liquid-gas case, it takes the form d(lnp)/dT = A HIRV- where R is the molar gas constant and A H is the molar enthalpy of vaporization. For the solid-gas case, A H is replaced by the molar enthalpy of sublimation, A H. [Pg.99]

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