Solubility electrolyte concentration

Niobic Acid. Niobic acid, Nb20 XH2O, includes all hydrated forms of niobium pentoxide, where the degree of hydration depends on the method of preparation, age, etc. It is a white insoluble precipitate formed by acid hydrolysis of niobates that are prepared by alkaH pyrosulfate, carbonate, or hydroxide fusion base hydrolysis of niobium fluoride solutions or aqueous hydrolysis of chlorides or bromides. When it is formed in the presence of tannin, a volurninous red complex forms. Freshly precipitated niobic acid usually is coUoidal and is peptized by water washing, thus it is difficult to free from traces of electrolyte. Its properties vary with age and reactivity is noticeably diminished on standing for even a few days. It is soluble in concentrated hydrochloric and sulfuric acids but is reprecipitated on dilution and boiling and can be complexed when it is freshly made with oxaHc or tartaric acid. It is soluble in hydrofluoric acid of any concentration. 

It is important to note that the solubility product relation applies with sufficient accuracy for purposes of quantitative analysis only to saturated solutions of slightly soluble electrolytes and with small additions of other salts. In the presence of moderate concentrations of salts, the ionic concentration, and therefore the ionic strength of the solution, will increase. This will, in general, lower the activity coefficients of both ions, and consequently the ionic concentrations (and therefore the solubility) must increase in order to maintain the solubility product constant. This effect, which is most marked when the added electrolyte does not possess an ion in common with the sparingly soluble salt, is termed the salt effect. 

Gas and liquid systems are explained by solubility. The solubility of oxygen at room temperature is about 10 ppm therefore the concentration of oxygen is 10 ppm (oxygen flux, Na). The solubility of oxygen at 0 °C is double that at 35 °C. Also, the solubility decreases if the electrolyte concentration is increased. The concentrations of oxygen in the gas phase and liquid phase are related to each other by the Raoult-Dalton equilibrium law. 

FIG. 1 Critical micelle concentration as a function of the number of carbon atoms in the hydrophobic rest of sodium a-sulfo fatty acid methyl esters. Methods O, surface tension +, conductivity A, solubilization of a dye x, solubility (all without electrolyte) , surface tension with a constant electrolyte concentration of 5 x 10"2 mol/L. (From Ref. 57.)... 

The same system has been studied previously by Boguslavsky et al. [29], who also used the drop weight method. While qualitatively the same behavior was observed over the broad concentration range up to the solubility limit, the data were fitted to a Frumkin isotherm, i.e., the ions were supposed to be specifically adsorbed as the interfacial ion pair [29]. The equation of the Frumkin-type isotherm was derived by Krylov et al. [31], on assuming that the electrolyte concentration in each phase is high, so that the potential difference across the diffuse double layer can be neglected. 

The typical solution present in the capillary consists of a polar solvent in which electrolytes are soluble. As an example, we can use methanol as solvent and a simple salt like NaCl or BHC1, where B is an organic base, as the solute. Low electrolyte concentrations, 10-5-10 3 mol/L (M), are typically used in electrospray mass spectrometry (ESMS). For simplicity we will consider only the positive ion mode in the subsequent discussion. 

Zhong et al. (2003) studied the apparent solubility of trichloroethylene in aqueous solutions, where the experimental variables were surfactant type and cosolvent concentration. The surfactants used in the experiment were sodium dihexyl sulfo-succinte (MA-80), sodium dodecyl sulfate (SDS), polyoxyethylene 20 (POE 20), sorbitan monooleate (Tween 80), and a mixture of Surfonic- PE2597 and Witconol-NPIOO. Isopropanol was used as the alcohol cosolvent. Eigure 8.20 shows the results of a batch experiment studying the effects of type and concentration of surfactant on solubilization of trichloroethylene in aqueous solutions. A correlation between surfactant chain length and solubilization rate may explain this behavior. However, the solubilization rate constants decrease with surfactant concentration. Addition of the cosolvent isopropanol to MA-80 increased the solubility of isopropanol at each surfactant concentration but did not demonstrate any particular trend in solubilization rate of isopropanol for the other surfactants tested. In the case of anionic surfactants (MA-80 and SDS), the solubility and solubilization rate increase with increasing electrolyte concentration for all surfactant concentrations. 

Drug release profiles from the tablets in various dissolution media are shown in Fig. 2. In all cases the release rates decreased initially from the control (distilled water) as electrolyte concentration increased, until a minimum release rate was obtained. As the electrolyte concentration further increased the release rates similarly increased until a burst release occurred. These initial decreases in release rates were probably coincident with a decrease in polymer solubility, in that as the ionic strength of the dissolution medium is increased the cloud point is lowered towards 37°C. It may be seen from Table 5 that minimum release rates occurred when the cloud point was 37°C. At this point the pore tortuosity within the matrix structure should also be at a maximum. It is unlikely to be an increase in viscosity that retards release rates since Ford et al. [1] showed that viscosity has little effect on release rates. Any reduction in hydration, such as that by increasing the concentration of solute in the dissolution media or increasing the temperature of the dissolution media, will start to prevent gelation and therefore the tablet will cease to act as a sustained release matrix. 

C, x = 1. For the compounds in this study, Equation 8 is used with x = 1 because their solubility is so low that the concentration is negligible compared with the total electrolyte concentration. Moreover, it is assumed that, at the pH s used in this study, the weak acids are completely ionized in solution. 

The experimental factors that affect the stability of the latex during and after polymerization are the recipe used for the polymerization, the type and intensity of agitation during and after the polymerization, the temperature of polymerization and storage, and the age and storage conditions of the latex. The recipe used in the polymerization included the mode of polymerization, the monomer-water ratio, the solubility of the monomer in water, the emulsifier type and concentration, initiator type and concentration, total electrolyte concentration, and impurities present in the system. 

The ionic strength effect is not limited to ksv variation as described by eq. (22). The addition of large amounts of electrolytes may also modify the quencher solubility and thus its efficiency. This effect has been used by some authors, in systems very different from those examined in this work, in order to determine the association constant of the inhibitor salt (Mac, 1997 Mac and Tokarczyk, 1999) as the electrolyte concentration is increased, the quencher ion associates, so that the effective concentration of the inhibitor ion decreases, leading to a downward curvature of the Stern-Volmer plot. Such a curvature can be quantitatively related... 

There is a common rule, called Bancroft s rule, that is well known to people doing practical work with emulsions if they want to prepare an O/W emulsion they have to choose a hydrophilic emulsifier which is preferably soluble in water. If a W/O emulsion is to be produced, a more hydrophobic emulsifier predominantly soluble in oil has to be selected. This means that the emulsifier has to be soluble to a higher extent in the continuous phase. This rule often holds but there are restrictions and limitations since the solubilities in the ternary system may differ from the binary system surfactant/oil or surfactant/water. Further determining variables on the emulsion type are the ratios of the two phases, the electrolyte concentration or the temperature. 

In the present paper, calculations are carried out to explain the restabilization followed sometimes by destabilization, as the electrolyte concentration increases, observed by Stenkamp et al. In these calculations, double-layer, steric, and depletion interactions are taken into account. The steric interaction at various electrolyte concentrations is calculated using the scaling theory. The surface density of the polymer chain was evaluated by using the Sechenov equation for the polymer solubility as a function of electrolyte concentration. 

To calculate the surface density of the polymer on the particles and the number of micelles at various electrolyte concentrations, the solubility of the polymer in the electrolyte solution is required. The Sechenov equation can be employed to calculate the solubility of apolymerin an electrolyte solution. This equation was initially proposed to calculate the solubility of a gas,22 but it is valid for a polymer solution as well.23 It has the form... 

Our explanation implies that the excess polymer precipitates onto the surface of the particles when the polymer concentration becomes larger than its solubility, which decreases with increasing electrolyte concentration in the solution. 

The main drawback of the AFC is the absorption of CO2 from the air by the alkaline solution. Carbon dioxide reacts with the hydroxide to form carbonate 2K+ + 20H- + CO2 - K2CO3 + H20, which has limited solubility in concentrated alkali, thus leading to deleterious precipitates within the electrode pores. Although there is no absolute solution to this problem, electrolyte replenishment, and upstream C02 scrubbers provide reasonable compromises. 

A typical solution present in the capillary consists of a polar solvent in which electrolytes are soluble. Low electrolyte concentrations, 10 5 to 10 3 mol 1, are typically used in ESMS. When turned on, the field Ec will penetrate the solution at the capillary tip and the positive and negative electrolyte ions in the solution will move under the influence of the field until a charge distribution results which counteracts the imposed field and leads to essentially field-free conditions inside the solution. When the capillary is the positive electrode, positive ions will have drifted downfield in the solution, i.e., toward the meniscus of the liquid, and negative ions will have drifted away from the surface. The mutual repulsion between the positive ions at the surface overcomes the surface tension of the liquid and the surface begins to expand, allowing the positive charges and liquid to move downfield. A cone forms, the so-called Taylor cone [19], and if the... 

Thus it can be stated that, in a saturated solution of a sparingly soluble electrolyte, the product of concentrations of the constituent ions for any given temperature is constant, the ion concentration being raised to powers equal to the respective numbers of ions of each kind produced by the dissociation of one molecule of the electrolyte. This principle was stated first by W. Nernst in 1889. 

Lyso PC and Lyso PE films. The knowledge in the field of interaction forces in foam films stabilised with soluble zwitterionic phospholipids lyso PC (lysophosphatidylcholine) and lyso PE (lysophosphatidylethanolamine) has improved due to the studies of microscopic foam films [e.g. 191,192,292], The main dependences studied were of film thickness vs. electrolyte concentration and disjoining pressure vs. thickness, under specially chosen conditions in the presence of Na+ and Ca2+. The /i(pH) dependence proved to be very informative for understanding the charge origin in films from the neutral phosopholipids lyso PC and lyso PE (see Section 3.3.2). 

The increased concentration of divalent cations could also be expected to displace trace metals from cation exchange sites as well as Ca and Mg. Although the exchangeable metal concentrations in many soils are low, exchangeable metal concentrations are generally much greater than soluble metals concentrations, and could act as a source to the solution phase under reducing conditions when electrolyte concentration (EC) is increased. 

The usual procedure, i.e., to diminish the q>2 potential by increasing the background electrolyte concentration, does not always work well in nonaqueous solvents, because in some solvents the typical salts used as background electrolytes have a limited solubility. 

The constant K s represents the slope of the graph, and the constant /S is given by the point of intersection of the straight line with the vertical axis and represents the logarithm of a hypothetical solubility at zero electrolyte concentration. 

The corresponding hydroxide, W(OH)j, has been prepared by the electrolytic reduction of solutions of tungsten trioxide in hydrochloric or hydrofluoric acid. It is a brown powder, insoluble in sodium hydro.xide, sulphuric acid, or acetic acid, but soluble in concentrated hydrochloric acid, yielding a greenish solution which rapidly becomes blue owing to oxidation of tetravalent tungsten to the pentavalent condition. 

The concentration of the solution at the anode is therefore diminished by i/ owing to the migration of v equivalents of the cation towards the cathode. The effect of the passage of the current is to transfer v equivalents of the soluble electrolyte from the anode to the cathode. 

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