Mixed-salt solutions, solubility

Solubility of Carbon Dioxide in Aqueous Mixed-Salt Solutions... 

T he solubility data of gases in aqueous mixed-salt solutions are funda-mentally important in research on liquid-gas mass transfer and in designing gas-liquid contacting operations, especially gas absorption accompanied by chemical reaction. 

The data have, however, been obtained for only a few systems by Onda et al. (J), Joosten and Danckwerts (2), and Hikita et al. (3). These authors also proposed methods for estimating the solubility of gases in aqueous mixed-salt solutions from the corresponding data for each salt in the systems. These studies are extensions of the empirical method proposed by van Krevelen and Hoftijzer (4) on the basis of the following modified Setschenow Equation. 

In the present investigation, the solubilities of carbon dioxide in aqueous mixed-salt solutions were measured at 25°C and 1 atm partial pressure of carbon dioxide, and the possibility of a method for estimating the solubility was discussed. 

Table I. Experimental Results of Carbon Dioxide Solubility in Aqueous Binary Mixed-Salt Solutions at 25°C and 1 atm...

In this study, Equation 2 was also used to correlate the solubility data of carbon dioxide in aqueous mixed-salt solutions. The values of A and B, obtained by the least squares method for all the systems, are summarized in Tables V, VI, VII, and VIII. 

In this study, the following equations were developed from Equation 2 to estimate the solubility of carbon dioxide in aqueous mixed-salt solutions from the solubility data in an aqueous solution of each salt component... 

The solubilities of carbon dioxide in aqueous solutions of seven binary and three ternary mixed salts chosen from eight kinds of electrolytes were measured at 25°C and 1 atm partial pressure of carbon dioxide by the saturation method. The experimental results were not correlated easily by the modified Setschenow equation, but they were correlated very well by the empirical two-parameter equation. The parameters in the equation for the binary and ternary solutions could be estimated by assuming an additive rule for the parameters of the component salt systems. This method, therefore, is useful for predicting the solubility of carbon dioxide in aqueous mixed-salt solutions. 

Fifth, the fit model has not been tested in mixed-salt solutions and against mineral solubility data (other than gypsum). It is not known whether an ion-association aqueous model, even with additional complexes, will be capable of accurately modeling these systems. 

As shown in Fig. 18-57, the mutual solubility of two salts can be plotted on the X and Y axes with temperatures as isotherm hues. In the example shown, all the solution compositions corresponding to 100°C with solid-phase sodium chloride present are shown on the Tine DE, All the solution compositions at equihbrium with solid-phase KCl at 100°C are shown by the line EE If both sohd-phase KCl and NaCl are present, the solution composition at equilibrium can only be represented by point E, which is the invariant point (at constant pressure). Connecting all the invariant points results in the mixed-salt hne. The locus of this line is an important consideration in making phase separations. 

When a salt dissolves in water, it produces cations and anions. Lead(II) nitrate and potassium iodide are soluble salts. Lead(II) nitrate dissolves in water to generate Pb cations and NO3 anions. Potassium iodide dissolves in water to generate K and I ions. Mixing the solutions combines all four types of ions. A precipitate forms if any of the new combinations of the ions forms a salt that is insoluble in water. The new combinations when these two solutions mix are K combining with NO3 or Pb combining with I ... 

If we were to conduct a second solubility experiment in which solutions of KI and NaN03 were mixed, we would find that no precipitate forms. This demonstrates that K and NO3 ions do not form a solid precipitate, so the bright yellow precipitate must be lead(II) iodide, Pbl2. As the two salt solutions mix, cations and r anions combine to produce lead(II) iodide, which precipitates from the solution. On standing, the yellow precipitate settles, leaving a colorless solution that contains potassium cations and nitrate anions. The molecular blowups in Figure depict these solutions at the molecular level. 

Buffer solutions are produced by mixing together solutions of a weak acid and its soluble, ionic salt or a weak base and its soluble, ionic salt in approximately the same concentrations. The concentration of one can be no more than ten times the concentration of the other. 

Knowing the value of the solubility product constant can also allow us to predict whether or not a precipitate will form if we mix two solutions, each containing an ion component of a slightly soluble salt. We calculate the reaction quotient (many times called the ion product), which has the same form as the solubility product constant. We take into consideration the mixing of the volumes of the two solutions, and then compare this reaction quotient to the K.p. If it is greater than the Ksp then precipitation will occur until the ion concentrations reduce to the solubility level. 

Onda, K. Sada, E. Kobayashi, T. Kita, S. Ito, K. "Solubility of Gases in Aqueous Solutions of Mixed Salts,"... 

Tests allowing precise determination of the conditions to protect the soluble protein, and of the temperature at which the reaction was slow enough for X-ray data collection, were sought. To ascertain the best conditions for the determination of the structure of a productive lysozyme-substrate complex, the hydrolysis of bacterial cell walls and oligosaccharides was investigated both in high-salt solutions and in mixed solvents. 

EXAFS studies on tris-maltolatoiron(III) in the solid state and in solution, and on [Fe(Ll)3] hydrate, pave the way for detailed investigation of the hydration of complexes of this type in aqueous media.Solubilities and transfer chemical potentials have been determined for tris-maltolatoiron(III) in methanol-water, and for tris-etiwlmaltolatoiron(III) in alcohol-water mixtures and in isobutanol, 1-hexanol, and 1-octanol. Solubility maxima in mixed solvents, indicating synergic solvation, is relevant to trans-membrane transport of complexes of this type. Solubilities of tris-ethylmaltolatoiron(III) and of [Fe(Ll)3] have been determined in aqueous salt solutions (alkali halides NH4 and NR4 bromides). ... 

A detailed description of salt mining will be postponed until the next chapter, but it is important to note that soda ash is made from both limestone and salt, the two major raw materials. As outlined in Fig. 5.2, the brine (salt solution) is mixed with ammonia in a large ammonia absorber. A lime kiln, using technology similar to that discussed earlier, serves as the source of carbon dioxide, which is mixed with the salt and ammonia in carbonation towers to form ammonium bicarbonate and finally sodium bicarbonate and ammonium chloride. Filtration separates the less soluble sodium bicarbonate from the ammonium chloride in solution. 

In aqueous solutions, calcium chloride undergoes double decomposition reactions with a number of soluble salts of other metals to form precipitates of insoluble calcium salts. For example, mixing solutions of calcium chloride with sodium carbonate, sodium tungstate and sodium molybdate solutions precipitates the carbonates, tungstates, and molybdates of calcium, respectively. Similar precipitation reactions occur with carboxylic acids or their soluble salt solutions. CaCb forms calcium sulfide when H2S is passed through its solution. Reaction with sodium borohydride produces calcium borohydride, Ca(BH4)2. It forms several complexes with ammonia. The products may have compositions CaCl2 2NH3, CaCb dNHs, and CaCb SNHs. 

The commercial product is obtained from naturally occurring mineral fluorspar, which is purified and powdered. Also, it may be precipitated by mixing a solution of sodium fluoride with a soluble calcium salt ... 

Copper(l) iodide is prepared by heating copper with iodine and concentrate hydriodic acid, HI. Another preparation route is precipitation of the salt by mixing aqueous solutions of potassium or sodium iodide with copper sulfate or any soluble copper(ll) salt ... 

Acid soluble rare earth salt solution after the removal of cerium may be subjected to ion exchange, fractional crystalhzation or solvent extraction processes to separate individual rare earths. Europium is obtained commercially from rare earths mixture by the McCoy process. Solution containing Eu3+ is treated with Zn in the presence of barium and sulfate ions. The triva-lent europium is reduced to divalent state whereby it coprecipitates as europium sulfate, EuS04 with isomorphous barium sulfate, BaS04. Mixed europium(ll) barium sulfate is treated with nitric acid or hydrogen peroxide to oxidize Eu(ll) to Eu(lll) salt which is soluble. This separates Eu3+ from barium. The process is repeated several times to concentrate and upgrade europium content to about 50% of the total rare earth oxides in the mixture. Treatment with concentrated hydrochloric acid precipitates europium(ll) chloride dihydrate, EuCb 2H2O with a yield over 99%. 

The acid chloride, [Co en2Cl2]Cl.HC1.2H20, is formed by mixing a solution of cobaltous chloride with an aqueous solution of ethylene-diamine monohydrate and oxidising the mixture with air. Concentrated hydrochloric acid is then added and the whole heated on a water-bath for one hour. The liquid is allowed to stand, when crystals separate, and are filtered and washed with concentrated hydrochloric acid.2 The salt crystallises in dark green rhombic plates. It is soluble in water, though less soluble than the normal salt, and on heating to 100° C. is transformed into the normal salt. 

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