Ideal mixture mixing process

The volume of an ideal gas mixture is given by eq. (3.6). Let us now consider only solid or liquid mixtures. Our starting point is an arbitrary mixture of nA mole of pure A and ng mole of pure B. The mixing process is illustrated in Figure 3.1. We... 

If mixture (A,B)N is ideal, mixing will take place without any heat loss or heat production. Moreover, the two cations will be fully interchangeable in other words, if they occur in the same amounts in the mixture, we will have an equal opportunity of finding A or B over the same structural position. The Gibbs free energy term involved in the mixing process is... 

So far, we have seen that deviation from ideal behavior may affect one or more thermodynamic magnitudes (e.g., enthalpy, entropy, volume). In some cases, we are able to associate macroscopic interactions with real (microscopic) interactions of the various ions in the mixture (for instance, coulombic and repulsive interactions in the quasi-chemical approximation). In practice, it may happen that none of the models discussed above is able to explain, with reasonable approximation, the macroscopic behavior of mixtures, as experimentally observed. In such cases (or whenever the numeric value of the energy term for a given substance is more important than actual comprehension of the mixing process), we adopt general (and more flexible) equations for the excess functions. 

Immiscibility phenomena in silicate melts imply positive deviations from ideality in the mixing process. Ghiorso et al. (1983) developed a mixing model applicable to natural magmas adopting the components listed in table 6.12. Because all components have the same standard state (i.e., pure melt component at the T and P of interest) and the interaction parameters used do not vary with T, we are dealing with a regular mixture of the Zeroth principle (cf sections 2.1 and 3.8.4) ... 

Mixed Micelles Showing Negative Deviation -from Ideality. In an aqueous solution containing a mixture o-f Cll an ionic sur-factant and a nonionic sur-factant, or C21 an anionic sur-factant and a cationic sur-factant, or C33 a zwitterionic sur-factant and an anionic sur-factant, the CMC o-f the mixed sur-factant system exhibits a CMC which is substantially less than that predicted by Equation 1 (9.12.18-37). This means that the mixed micelle -formation is enhanced and that the mixing process in the micelle shows negative deviation -from ideality. This is demonstrated -for a cationic/nonionic system in Figure 1. 

We are rarely able to extract much work from chemical reactors. WTe mostly take out energy from the reactor in the form of heat. Also, when we let a hot stream heat up a cold stream in a heat exchanger we lose some of the work potential of the hot stream. The same is true for mixing and material flow across a pressure drop we take advantage of the spontaneity of the process and make no attempt to recover work from it. In contrast, we often want to perform operations that are the reverse to the spontaneous direction. This always requires work. For example, separation is the opposite of mixing. The work demand of separating an ideal mixture of n components into pure products at constant temperature T is... 

In a mixture of ideal gases the sound velocity and consequently the resonant frequencies of a resonator depend on the effective specific heat ratio and the average molecular mass of the mixture. Chemical reaction and mixing processes, for example, are normally accompanied with a change of these properties. Therefore, such dynamic processes can be monitored by a repeated measurement of the shift of one of the eigenfrequencies of the resonator as a function of time. 

Side Effects in the Ideal Case Changes of volume and entropy in mixing processes work just like those of chemical processes discussed in Chap. 8. Let us again consider a homogeneous mixture of two indifferent substances A and B. Because... 

The Equilibrium reactor is a vessel which models equilibrium reactions. The outlet streams of the reactor are in a state of chemical and physical equilibrium. The reaction set which you attach to the Equilibrium reactor can contain an unlimited number of equilibrium reactions, which are simultaneously or sequentially solved. Neither the components nor the mixing process need be ideal, since HYSYS can compute the chemical activity of each component in the mixture based on mixture and pure component fugacities. 

Thus, the mixing of liquids that form an ideal mixture is an athermal process, one in which no heat transfer is needed to keep the temperature constant. 

The reversible mixing process depicted in Fig. 11.3 illustrates this principle. The initial state shown in Fig. 11.3(a) consists of volume V (A) of pure ideal gas A and volume V (B) of pure ideal gas B, both at the same T and p. The hypothetical semipermeable pistons are moved apart reversibly and isothermally to create an ideal gas naixture, as shown in Fig. 11.3(b). According to an argument in Sec. 9.3.3, transfer equiUbrium across the semipermeable pistons requires partial pressure px in the mixture to equal the pressure of the pure A at the left, and partial pressure pe in the nuxture to equal the pressure of the pure B at the right. Thus in intermediate states of the process, gas A exerts no net force on piston 1, and gas B exerts no net force on piston 2. 

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