Solubility of one liquid in another

Suppose substances A and B are both liquids when pure. In discussing the solubility of liquid B in liquid A, we can treat B as either a solute or as a constituent of a liquid mixture. The difference lies in the choice of the standard state or reference state of B. 

We can define the solubility of B in A as the maximum amount of B that can dissolve without phase separation in a given amount of A at the given temperature and pressure. Treating B as a solute, we can express its solubility as the mole fraction of B in the phase at the point of phase separation. The addition of any more B to the system will result in two coexisting liquid phases of fixed composition, one of which will have mole fraction xb equal to its solubility. 

Consider a system with two coexisting liquid phases a and P containing components A and B. Let a be the A-rich phase and P be the B-rich phase. For example, A could be water and B could be benzene, a hydrophobic substance. Phase a would then be an aqueous phase polluted with a low concentration of dissolved benzene, and phase P would be wet benzene. X3 would be the solubility of the benzene in water, expressed as a mole fraction. 

relations are derived for this kind of system using both choices of standard state or reference state. 

Assume that the two components have low mutual solubilities, so that B has a low mole fraction in phase a and a mole fraction close to 1 in phase p. It is then appropriate to treat B as a solute in phase a and as a constituent of a liquid mixture in phase p. The value of Xg is the solubility of liquid B in liquid A. 

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There are some cases, when solubility of one liquid in another decreases with the rise in temperature. 

Triethylamine and Water.— Although in most of the cases studied the solubility of one liquid in another increases with rise of temperature, this is not so in all cases. Thus, at temperatures below 18 , triethYlamine and water mix together. all4mpoxti ne oh raJiJig the temperature,... ft homog eneous solution becomes turbid... 

The salient features of the theory of wetting transition and some experimental observations have been reviewed by de Geimes (1985). The experiments, which are performed solely on liquid-liquid systems, do not always conform with the theoretical predictions because of trace impurities, slow equilibration and fluctuations, and the solubility of one liquid in another. Schmidt (1988) reports the results of studies on water against a homologous series of fluorocarbons which support all of the theoretical findings. 

There are some cases, when solubility of one liquid in another decreases with the rise in temperature. The temperature-composition cmwe for triethylamine and water system is shown in figm-e (3). 

Alloys are classified broadly in two categories, single-phase alloys and multiple-phase alloys. A phase is characterized by having a homogeneous composition on a macroscopic scale, a uniform structure, and a distinct interface with any other phase present. The coexistence of ice, liquid water, and water vapor meets the criteria of composition and structure, but distinct boundaries exist between the states, so there are three phases present. When liquid metals are combined, there is usually some limit to the solubility of one metal in another. An exception to this is the liquid mixture of copper and nickel, which forms a solution of any composition between pure copper and pure nickel. The molten metals are completely miscible. When the mixture is cooled, a solid results that has a random distribution of both types of atoms in an fee structure. This single solid phase thus constitutes a solid solution of the two metals, so it meets the criteria for a single-phase alloy. 

Very pure germanium is made by the method of zone refining, usually achieved by slowly traversing a rod of solid with a molten zone by means of radio-frequency heating. Impurities are concentrated in a short section at one end of the bar, which is discarded. The success of the process depends on the difference between the solid and liquid solubilities of one element in another at the point of solidification. 

It is important to distinguish between these two kinds of forces. It is the inter-molecular forces that determine such properties as the solubility of one substance in another and the freezing and boiling points of liquids. But, at the same time we must realize that these forces are a direct consequence of the intramolecular forces in the individual units, the molecules. 

SECTION 13l3 The solubility of one substance in another depends on the tendency of systems to become more random, by becoming more dispersed in space, and on the relative intermolecular solute solute and solvent solvent enei es compared with solute solvent interactions. Polar and ionic solutes tend to dissolve in polar solvents, and nonpolar solutes tend to dissolve in nonpolar solvents ( like dissolves like ). Liquids that mix in all proportions are miscible those... 

Emulsions are dispersions of small droplets of one liquid in another liquid, neither liquid being soluble in the other. They are electrically stabilised by some type of surface active substances know as emulsifiers. When the amount of the emulsifier is small, the emulsion is relatively unstable ( loose emulsion) and the dispersed droplets coalesce fairly easily to give large drops ( cracking of emulsion). When the concentration of the emulsifier is large, the dispersed droplets are finer and the emulsion is hard to break ( tight or stable emulsion). 

To separate solutions of both liquids and of solids in a liquid (particularly water), two methods usually are considered first (1) vaporization—i.e., evaporation or distillation—to utilize the different relative volatilities of the components, either normally or accentuated by another liquid in azeotropic or extractive distillation and (2) liquid-liquid extraction to take advantage of the relative preferential solubility of one component in an added liquid. 

When one pure liquid exists in the presence of another pure liquid, where the liquids neither react nor are soluble in each other, the vapor pressure of one liquid will not affect the vapor pressure of the other liquid. The sum of the partial pressures P is equal to the total pressure P. This relationship is formalized in Dalton s Law, which is expressed as... 

Absorption. In theory, the penetration of one substance into another. In refining and petrochemicals processing, separation of gases by a scrubbing or washing operation with a liquid. Preferential solubility is shown for one or more of the components in the gas mixture allowing a separation... 

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