Sodium sulfate, dissociation

A dissociable molecule in this case sodium sulfate (1 mole)... 

The chemical category of inorganic salts encompasses many substances that dissociate completely in water, but only one salt, sodium chloride, is referred to by the common name, salt. Sodium chloride is ubiquitous in both its occurrence and its many uses. To date, there are over 14,000 uses for salt.1 Salt is used as a feedstock for many chemicals including chlorine, caustic soda (sodium hydroxide), synthetic soda ash (sodium carbonate), sodium chlorate, sodium sulfate, and metallic sodium. By indirect methods, sodium chloride is also used to produce hydrochloric acid and many other sodium salts. In its natural mineral form, salt may take on some color from some of the trace elements and other salts present, however, pure sodium chloride is a white to colorless crystalline substance, fairly soluble in water.2 Also known as halite, the substance... 

Rabbit-muscle phosphorylase a and b have been reported to dissociate into subunits having molecular weights of 242,000 and 135,000 respectively (see Table XVII), although it has been reported that subunits having weight 60,000 may be obtained on treatment with dodecyl sodium sulfate. Isozymes of rabbit-heart phosphorylase have, however, been reported, and these may be occasioned by differences in subunit structure. 

From (4-26), for a 1 1 electrolyte in water the Bjerrum critical distance is 3.6 X 10 cm. When it is realized that ions in water are normally highly solvated and that the sum of ionic crystal radii for typical anions and cations often approaches or exceeds 3.6 x 10 cm, it is reasonable to find that dissociation constants for ion pairs in water are large thus for sodium hydroxide the dissociation constant is about 5. On the other hand, for a 2 2 electrolyte in water the critical distance is 14.3 x 10 cm, and for a 1 1 electrolyte in ethanol, 11.5 x 10 cm. In these cases, even highly solvated ions can readily approach to the distance necessary to form an ion pair. For magnesium sulfate the dissociation constant in water is 6 x 10 , and for sodium sulfate, 0.2. 

Like in DLI, there are no sodium containing ions to be found in the TSP mass spectra of the sodium salts of BaP sulfates. Dissociation of this salt is again likely to be responsible, since an 80% aqueous 0.1 M solution of ammonium acetate and 20% acetonitrile was used as the mobile phase. 

In the experimental determination of activity coefficients of strong electrolytes, by the methods described below, the molalities, etc., of the ions are taken as the stoichiometric values, that is, the total possible molality, etc., disregarding incomplete dissociation, For example, in the last problem, the molalities of the sodium and sulfate ions in the 0.5 molal solution of sodium sulfate were taken as exactly 1.0 and 0.5, respectively, without allowing for the possibility that the salt may be only partially dissociated at the specified concentration. The activity coefficients obtained in this manner are called stoichiometric activity coefficients they allow for all variations from the postulated ideal behavior, including that due to incomplete dissociation. If the treatment is based on the actiuil ionic molalities, etc., in the given solution, as in the Debye-Httckel theory (Chapter XVII), there is obtained the true (or actual) activity coefficient. TTie ratio... 

In an aqueous solution, ionic compounds are completely dissociated into ions. For example, an aqueous solution of barium nitrate, Ba(N03)2, contains Ba + ions and NO3 ions. If aqueous solutions of ionic compounds are mixed, some ions may interact to form an insoluble product called a precipitate. For example, if aqueous solutions of barium nitrate and sodium sulfate are mixed, insoluble barium sulfate will precipitate. The complete formula equation for this reaction is written as follows. 

It goes without saying that suspended transformations may also accompany the phase interconversions of anhydrates and solvates. Efflorescence may not occur immediately once the pressure is reduced below the dissociation pressure, but such reactions will always take place upon formation of a suitable nucleus. For instance, it has been known since the time of Michael Faraday that the decahydrate phase of sodium sulfate is unstable with respect to open air, since the vapor pressure of the salt exceeds the vapor pressure of water vapor at room temperature. However, the system only dehydrates upon contact with the anhydrate phase, demonstrating the metastable nature of the decahydrate phase. 

The sodium lauryl sulfate dissociates into sodium and lautyl sulfate ions in solution. 

Molar ratio (MR) between sulfuric acid and sodium sulfate at constant sodium sulfate concentration. The second dissociation constant of sulfuric acid is rather low, in the range of 0.01. Consequently, in a solution containing both sulfuric acid and sodium sulfate at MR < 1, substantially all the sulfuric acid reacts with the stoichiometric amount of sodium sulfate to give sodium bisulfate (buffer action). Hence, the actual concentration of free protons (H ) is directly proportional to the actual concentration of sodium bisulfate and inversely proportional to that of the unreacted sodium. sulfate. This type of dependence indicates that the actual concentration of free protons should increase quickly when MR exceeds a certain critical value (ca. 0.5). At higher MR values the current transported by the protons becomes significant at the expense of that transported by the sodium ions, and the cathodic efficiency shows a sharp decrease. 

We can usually predict the nature of the ions in a solution of an ionic compound from the chemical name of the substance. Sodium sulfate (Na2S04), for example, dissociates into sodium ions (Na ) and sulfate ions (804 ). You must remember the formulas and charges of common ions (Tables 2.4 and 2.5) to understand the forms in which ionic compounds exist in aqueous solution. 

To produce viscose silk (rayon), the next stage is spinning under 3-5 bar pressure into what is known as a Muller bath, which consists of 7-12% H2SO4, 16-23% Na2S04, and 1-6% Zn-Mg-NH4-sulfate. Here, two events occur simultaneously coagulation of the cellulose xanthate and hydrolytic decomposition to cellulose with the reformation of CS2. As by-products, H2S and COS are found in the exhaust air and elementary sulfur (as sodium polysulfides) in the bath and on the fibers. Sodium sulfate should decrease dissociation and thus lessen the osmotic pressure drop of the bath with its high electrolyte content relative to the fiber gel, which is low in electrolytes. 

Although there is ample evidence of its existence, the NaSO ion is generally ignored when calculating activity coefficients in solutions containing sodium and sulfate ions. Sodium sulfate is treated as a completely dissociating electrolyte. As early as 1930. Righellato and Davies (S34) stated that, even in dilute solutions, most uni-bivalent salts are incompletely dissociated. Based on conductance measurements at 18 C, they presented dissociation constants for a number of intermediate ions. For the salt MzX the dissociations were defined ... 

In the case of a soluble ionic compound with other than a 1 1 combination of constituent ions, we must use the subscripts in the chemical formula to determine the concentration of each ion in solution. Sodium sulfate (Na2S04) dissociates, for example, to give twice as many sodium ions as sulfate ions. 

Typical behaviour of osmotic and activity coefficients as calculated using Eqs. (5.36) and (5.37), is illustrated for trisodium citrate and tripotassium citrate in Fig. 5.15. It can be observed, that values of the (/w) and y+(/w) coefficients after a strong fall in very dilute solutions depend rather weakly on the citrate concentration. Since a T-,m) values are nearly temperature independent, the same is observed in the case osmotic and activity coefficients. It is worthwhile to mention that the Pitzer model was also used by Schunk and Maurer [163] when they determined water activities at 25 °C in ternary systems (citric acid + inorganic salt). The interactions parameters between ions, which were applied to represent activities in ternary systems, were calculated by taking into account the dissociation steps of citric acid and the formation of bisulfate ions for solutions with sodium sulfate. 

In 1966 two research groups (Ogawa et al, 1966 Thornber et al. 1966) were the first to demonstrate that sodium do-decyl sulfate dissociated thylakoid membranes can be separated into three different zones two of which represent chlorophyll-proteins. Analysis of the two chlorophyll-protein zones, which were termed components or complexes I and II, respectively, revealed most, if not all, of the Chi b associated with complex II whilst complex I contained mainly Chi a. 

Water-soluble peroxide salts, such as ammonium or sodium persulfate, are the usual initiators. The initiating species is the sulfate radical anion generated from either the thermal or redox cleavage of the persulfate anion. The thermal dissociation of the persulfate anion, which is a first-order process at constant temperature (106), can be greatly accelerated by the addition of certain reducing agents or small amounts of polyvalent metal salts, or both (87). By using redox initiator systems, rapid polymerizations are possible at much lower temperatures (25—60°C) than are practical with a thermally initiated system (75—90°C). 

Shedlovsky et al. studied mixtures of sodium decyl, dodecyl, and tetradecyl sulfates by electromotive force measurements and determined the extent of the dissociation of the sodium counterions by the micelles. From the data obtained strong interaction below the CMC was found for all of the mixtures except those containing more than 25 mol % of sodium decyl sulfate [122]. Commercial alcohol sulfates are mixtures of homologs with different hydrocarbon chains. It has been demonstrated [123] that the CMC of such products is lower than that expected by calculation from the linear relationship between log CMC and the number of carbon atoms of the alcohol as stated in Eq. (11). These results are shown in Fig. 9. 

Fujiwara et al. used the CMC values of sodium and calcium salts to calculate the energetic parameters of the micellization [61]. The cohesive energy change in micelle formation of the a-sulfonated fatty acid methyl esters, calculated from the dependency of the CMC on the numbers of C atoms, is equivalent to that of typical ionic surfactants (Na ester sulfonates, 1.1 kT Ca ester sulfonates, 0.93 kT Na dodecyl sulfate, 1.1 kT). The degree of dissociation for the counterions bound to the micelle can be calculated from the dependency of the CMC on the concentration of the counterions. The values of the ester sulfonates are also in the same range as for other typical ionic surfactants (Na ester sulfonates, 0.61 Ca ester sulfonates, 0.70 Na dodecyl sulfate, 0.66). 

Microtubule-associated proteins bind to microtubules in vivo and subserve a number of functions including the promotion of microtubule assembly and bundling, chemomechanical force generation, and the attachment of microtubules to transport vesicles and organelles (Olmsted, 1986). Tubulin purified from brain tissue by repeated polymerization-depolymerization contains up to 20% MAPs. The latter can be dissociated from tubulin by ion-exchange chromatography. The MAPs from brain can be resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). 

Oshima et al. explored a cationic rhodium-catalyzed intramolecular [4+2] annulation of l,3-dien-8-ynes in water in the presence of sodium dodecyl sulfate (SDS), an anionic surfactant.132 When the substrate l,3-dien-8-yne was a terminal alkyne, the reaction provided an inter-molecular [2+2+2] product (Eq. 4.68). In water, a reactive cationic rhodium species was formed by the dissociation of the Rh-Cl bond in the presence of SDS. The SDS forms negatively charged micelles, which would concentrate the cationic rhodium species (Scheme 4.15). 

The virial methods differ conceptually from other techniques in that they take little or no explicit account of the distribution of species in solution. In their simplest form, the equations recognize only free ions, as though each salt has fully dissociated in solution. The molality m/ of the Na+ ion, then, is taken to be the analytical concentration of sodium. All of the calcium in solution is represented by Ca++, the chlorine by Cl-, the sulfate by SO4-, and so on. In many chemical systems, however, it is desirable to include some complex species in the virial formulation. Species that protonate and deprotonate with pH, such as those in the series COg -HCOJ-C02(aq) and A1+++-A10H++-A1(0H), typically need to be included, and incorporating strong ion pairs such as CaSO aq) may improve the model s accuracy at high temperatures. Weare (1987, pp. 148-153) discusses the criteria for selecting complex species to include in a virial formulation. 

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