Solution gas-liquid

For the absorption of a gas (like carbon dioxide) into a liquid (like water) Henry s law stales that partial pressure of the gas is proportional to the mole fraction of the gas in the liquid-gas solution with the constant of proportionality being Henry s constant. A bottle of soda pop (CO2-H2O) at room temperature has a Henry s constant of l7,l(X)kPa. If the pressure in this bottle is 120 kPa and the partial pressure of the water vapor in the gas volume at the top of the bottle is neglected, the concentration of the CO2 in the liquid HjO is (a) 0.003 mol-COj/mol (6) 0.007 mol-COj/mol... 

Liquid-Gas Soiutions Carbonated beverages are liquid-gas solutions—carbon dioxide is the gaseous solute, and water is the liquid solvent. The carbon dioxide gas gives the beverage its fizz and some of its tartness. The beverage also might contain other solutes, such as the compounds that give it its flavor and color. 

Solubility in Liquid-Gas Solutions Unlike liquid-solid solutions, an increase in temperature decreases the solubility of a gas in a liquid-gas solution. You might notice this if you have ever opened a warm carbonated beverage and it bubbled up out of control while a chilled one barely fizzed. Carbon dioxide is less soluble in a warm solution. What keeps the carbon dioxide from bubbling out when it is sitting at room temperature on a supermarket shelf When a bottle is filled, extra carbon dioxide gas is squeezed into the space above the liquid, increasing the pressure in the bottle. This increased pressure increases the solubility of gas and forces most of it into the solution. When you open the cap, the pressure is released and the solubility of the carbon dioxide decreases. 

Describe how a liquid-solid solution forms. How is this different from a liquid-gas solution How are these two types of solutions different from a liquid-liquid solution Give an example of each with your description. 

Why is a carbonated beverage defined as a liquid-gas solution In an open container, the ratio of liquid solvent to gas solute changes over time. Explain. 

Figure 1, Composition of the critical cluster (bubble of critical size), Xgas, thermodynamic driving force of critical bubble formation, CJ,radius of the critical bubble, Rc, and work of critical bubble formation, [J Gc, computed for the case of boiling in binary liquid-gas solutions in dependence on supersturation here expressed via the density of the liquid puq (for the details see Ref 21). By the number (1), the results are shown computed via the classical Gibbs approach employing the capillarity approximation, number (2) refers to computations via the generalized Gibbs approach and number (3) to computations via the van der Waals square gradient density functional method.

We rarely have occasion to consider reactions where all products and reactants are in their standard states. Therefore, we need another difference term, the difference between G° of each product and reactant in its standard state, and G of each in the real state we are interested in. This is the function of the activity, a (dimensionless) quantity which tells us this difference. Thus, for any substance (solid, liquid, gas, solute, or ion) i, we define the activity a such that... 

On the other hand, if even one of the reaction constituents has a standard state with a variable pressure, normally P° = P, then equation (13.27) is not true, and integration of equation (13.28) requires a knowledge of how ArG° varies with pressure. We will simplify the following discussion by assuming that reaction constituents having the same physical state (solid, liquid, gas, solute) will have the same kind of standard... 

Gases can dissolve in liquids. In fact, liquid/gas solutions are important to us. One example is a soft drink, which has carbon dioxide gas dissolved in water. Another example is the ocean, where the solubility of oxygen is crucial to fish and other animal life, and the solubility of carbon dioxide is important for algae and other plant life. In fact, the ability of the oceans to dissolve gases is largely unknown but is thought to be a major factor in the weather conditions of the troposphere (the layer of the atmosphere closest to the surface of the earth). 

Liquid/gas solutions range between extremes. Hydrogen chloride gas, HCl, is very soluble in water, making solutions of hydrochloric acid. By contrast, the solubility of 1 bar of pure oxygen in water is only about 0.0013 M. 

Figure Bl.22.8. Sum-frequency generation (SFG) spectra in the C N stretching region from the air/aqueous acetonitrile interfaces of two solutions with different concentrations. The solid curve is the IR transmission spectrum of neat bulk CH CN, provided here for reference. The polar acetonitrile molecules adopt a specific orientation in the air/water interface with a tilt angle that changes with changing concentration, from 40° from the surface nonnal in dilute solutions (molar fractions less than 0.07) to 70° at higher concentrations. This change is manifested here by the shift in the C N stretching frequency seen by SFG [ ]. SFG is one of the very few teclnhques capable of probing liquid/gas, liquid/liquid, and even liquid/solid interfaces.

Gravimetric methods based on precipitation or volatilization reactions require that the analyte, or some other species in the sample, participate in a chemical reaction producing a change in physical state. For example, in direct precipitation gravimetry, a soluble analyte is converted to an insoluble form that precipitates from solution. In some situations, however, the analyte is already present in a form that may be readily separated from its liquid, gas, or solid matrix. When such a separation is possible, the analyte s mass can be directly determined with an appropriate balance. In this section the application of particulate gravimetry is briefly considered. 

Fig. 6. Schematic of dry-jet wet spinning employing tube-in-orifice spinneret A, bore injection medium (liquid, gas, or suspended soHds) B, pump C, spinneret D, polymer spinning solution E, micrometer ( -lm) "dope" filter F, coagulation or cooling bath G, quench bath and H, collection spool.

Xi Mole-fraction solute in hquid at gas-hquid interface (kmol solute)/(kmol liquid) (Ibmol solute)/(lbmol hquid)... 

FIG. 14-11 Gas-ph ase and liquid-phase solute-concentration profiles for an extremely slow (IdneticaUy limited) reaction system for which is less than 0.3. 

FIG. 14-13 Gas-phase and liquid-phase solute-concentration profiles for a liquid-phase mass-transfer limited reaction system in which is larger than 3. 

The scrubbing liquid must be chosen with specific reference to the gas being removed. The gas solubility in the liquid solvent should be high so that reasonable quantities of solvent are required. The solvent should have a low vapor pressure to reduce losses, be noncorrosive, inexpensive, nontoxic, nonflammable, chemically stable, and have a low freezing point. It is no wonder that water is the most popular solvent used in absorption devices. The water may be treated with an acid or a base to enhance removal of a specific gas. If carbon dioxide is present in the gaseous effluent and water is used as the scrubbing liquid, a solution of carbonic acid will gradually replace the water in the system. 

Physical and Chemical Properties - Physical State at 15 X) and I atm. Solid (anhydrous) Liquid (10% solution) Molecular Weight 116.21 Boiling Point at I atm. 478, 205, 401 Freezing Point (anhydrous) 104.9, 40.5, 313.7 (70% solution) 28, -2, 269 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity (anhydrous) 0.799 at 20 °C, (liquid) (70 % solution) 0.933 at 20°C, (liquid) Vapor (Gas) Specific Gravity Not pertinent Ratio of Specific Heats of Vapor (Gas) Not ptrimexA Latent Heat of Vaporization 3,4.73 Heat of Combustion (est.)-12,200,... 

Fig. 10 shows the radial particle densities, electrolyte solutions in nonpolar pores. Fig. 11 the corresponding data for electrolyte solutions in functionalized pores with immobile point charges on the cylinder surface. All ion density profiles in the nonpolar pores show a clear preference for the interior of the pore. The ions avoid the pore surface, a consequence of the tendency to form complete hydration shells. The ionic distribution is analogous to the one of electrolytes near planar nonpolar surfaces or near the liquid/gas interface (vide supra). 

Just as the solid/liquid phase equilibria in the systems HX/H2O show several points of interest, so too do the liquid/gas phase equilibria. When dilute aqueous solutions of HX are heated to boiling the concentration of HX in the vapour is less than that in the liquid phase, so that the liquid becomes progressively more concentrated and the bp progressively rises until a point is reached at which the liquid has the same composition as the gas phase so that it boils without change in composition and at constant temperature. This mixture is called an azeotrope (Greek a, without zein, to boil rpo7tr, trope, change). 

Henry s Law. This is an empirical formulation that describes equilibrium solubilities of noncondensable gases in a liquid when Raoult s law fails. It states that the mole fraction of a gas (solute i) dissolved in a liquid (solvent) is proportional to the partial pressure of the gas above the liquid surface at given temperature. That is,... 

Let us first consider the three-phase equilibrium ( -clathrate-gas, for which the values of P and x = 3/( +3) were determined at 25°C. When the temperature is raised the argon content in the clathrate diminishes according to Eq. 27, while the pressure can be calculated from Eq. 38 by taking yA values following from Eq. 27 and the same force constants as used in the calculation of Table III. It is seen that the experimental results at 60°C and 120°C fall on the line so calculated. At a certain temperature and pressure, solid Qa will also be able to coexist with a solution of argon in liquid hydroquinone at this point (R) the three-phase line -clathrate-gas is intersected by the three-phase line -liquid-gas. At the quadruple point R solid a-hydroquinone (Qa), a hydroquinone-rich liquid (L), the clathrate (C), and a gas phase are in equilibrium the composition of the latter lies outside the part of the F-x projection drawn in Fig. 3. The slope of the three-phase line AR must be very steep, because of the low solubility of argon in liquid hydroquinone. 

Before subjecting L. L. Blyler and T. K. Kwei s work to criticism, let us point out its strong points. First and foremost, this concerns the question How does gas behave after dissolving in the melt Analysis of gas solutions in low-molecular liquids is, evidently, based on the same grounds as the one for solutions of low-molecular liquid vapours with sufficiently large molecules in polymer melts. 

On account of the very great difficulty of measuring the extremely small amounts of adsorbed substance at a liquid/gas or liquid/liquid interface, very few experiments are available for testing Gibbs s equation. Zawidski(13) (1900) pointed out that the concentration of the foam of a solution should be different from that of the latter in bulk, and Miss Benson (14> (1903) by the analysis of a solution of amyl alcohol in water found... 

As mentioned earlier, the physical properties of a liquid mixture near a UCST have many similarities to those of a (liquid + gas) mixture at the critical point. For example, the coefficient of expansion and the compressibility of the mixture become infinite at the UCST. If one has a solution with a composition near that of the UCEP, at a temperature above the UCST, and cools it, critical opalescence occurs. This is followed, upon further cooling, by a cloudy mixture that does not settle into two phases because the densities of the two liquids are the same at the UCEP. Further cooling results in a density difference and separation into two phases occurs. Examples are known of systems in which the densities of the two phases change in such a way that at a temperature well below the UCST. the solutions connected by the tie-line again have the same density.bb When this occurs, one of the phases separates into a shapeless mass or blob that remains suspended in the second phase. The tie-lines connecting these phases have been called isopycnics (constant density). Isopycnics usually occur only at a specific temperature. Either heating or cooling the mixture results in density differences between the two equilibrium phases, and separation into layers occurs. 

Tenet (v). Experimental studies of the interaction of a solid with a gas, liquid or solute must ensure that there is uniform availability of the homogeneous participant at all surfaces within an assemblage of reactant crystallites if meaningful kinetic measurements relating to the chemical step are to be obtained. If this is not achieved, then diffusion rates will control the overall rate of product formation. Such effects may be particularly significant in studies concerned with finely divided solids. 

Reaction of a solid with a liquid (or solute) As with solid and gas Diffusion in the liquid may be important, particularly where no barrier layer is formed... 

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