Solubility product definition

Sigma (a) bonds Sigma bonds have the orbital overlap on a line drawn between the two nuclei, simple cubic unit cell The simple cubic unit cell has particles located at the corners of a simple cube, single displacement (replacement) reactions Single displacement reactions are reactions in which atoms of an element replace the atoms of another element in a compound, solid A solid is a state of matter that has both a definite shape and a definite volume, solubility product constant (/ p) The solubility product constant is the equilibrium constant associated with sparingly soluble salts and is the product of the ionic concentrations, each one raised to the power of the coefficient in the balanced chemical equation, solute The solute is the component of the solution that is there in smallest amount, solution A solution is defined as a homogeneous mixture composed of solvent and one or more solutes. 

Throughout this review of biomineralization, one outstanding phenomenon has been consistently evaded. This is the problem of apparent solubility products and supersaturation. It is obvious, however, that almost by definition this is the one phenomenon that directly relates to the whole problem, but it is consistently evaded because there is no simple theory to account for the observations. In order to highlight the importance of this phenomenon, therefore, an attempt will be made to relate extracellular theories to this concept. 

By definition the reactant for any solubility product constant reaction must be a solid and the solvent must be water, so this is the general form of any Ksp and the equation always simplifies down to a nonfraction. From this expression the solubility of Ca3(As04)2-4.25H20 is easily calculated. Based on Equation 2.31, the dissolution of 1 mole of the solid will generate three moles of Ca2+ and two moles of AsCL3-. Therefore ... 

This equation also can be derived from Eq. 3.32 after incorporating the definition of ideal mixing. For an ideal Al-goethite, Eqs. 3.39 and 3.43 yield the solubility product constant ... 

The solubility product is defined for a semi-infinite plane surface where the interfacial energy between the crystal and the solution makes a negligible contribution to the free-energy of formation of the particle. The definition also necessitates that the solid phase is homogeneous in structure and that a chemical potential may be assigned to the components irrespective of their position within the solid. When the crystals are small this may not be true because the imbalance of interionic forces at the surface produce... 

Solubility Equilibria The Solubility Product Principle.—It was seen on page 133 that the chemical potential of a solid is constant at a definite temperature and pressure consequently, when a solution is saturated with a given salt Mv A, the chemical potential of the latter in the solution must also be constant, since the chemical potential of any substance present in two phases at equilibrium must be the same in each phase. It is immaterial whether this conclusion is applied to the undissociated molecules of the salt or to the ions, for the chemical potential is given by... 

Activity Coefficients from Solubility Measurements.—The activity coefficient of a sparingly soluble salt can be determined in the presence of other electrolytes by making use of the solubility product principle. In addition to the equations already given, this principle may be stated in still another form by introducing the definition of the mean ionic concentration, i.e., c , which is equal to c+clr, into equation (109) this equation then becomes... 

The foregoing example illustrates how equilibrium constants for overall cell reactions can be determined electrochemically. Although the example dealt with redox equilibrium, related procedures can be used to measure the solubility product constants of sparingly soluble ionic compounds or the ionization constants of weak acids and bases. Suppose that the solubility product constant of AgCl is to be determined by means of an electrochemical cell. One half-cell contains solid AgCl and Ag metal in equilibrium with a known concentration of CP (aq) (established with 0.00100 M NaCl, for example) so that an unknown but definite concentration of Kg aq) is present. A silver electrode is used so that the half-cell reaction involved is either the reduction of Ag (aq) or the oxidation of Ag. This is, in effect, an Ag" Ag half-cell whose potential is to be determined. The second half-cell can be any whose potential is accurately known, and its choice is a matter of convenience. In the following example, the second half-cell is a standard H30" H2 half-cell. 

Note that when the value of one of the previous equilibrium constants, exchange constants, or solubility products is taken from other sources, attention should be paid to the definition. For example, the solubility product of Ca(OH)2 is commonly defined as... 

The design of the experiment is not well suited for an equilibrium analysis, but definitely showed that Ag2Se03(cr) is dissolved by an excess of SeOj. No equilibrium constants were derived in the paper from these data. The review calculated ((A.22), 298.15 K) from the data at the lowest total selenite concentration and pH < 6. The protonation constants from the first series were used in the calculation. The result was log Ai, ((A.22), 298.15 K) = - (15.20 + 0.15). Hence there is a significant difference between the values of the solubility product determined by the two techniques, which cannot be accounted for and apparently not observed by the authors. 

As an aside, the nomenclature of the coal tar industry, like that of the petroleum industry (Speight, 2007), needs refinement and clarification. Almost any black, undefined, semisolid-to-liquid material is popularly, and often incorrectly, described as tar or pitch whether it be a manufactured product or a naturally occurring substance (Chapter 16). However, to be correct and to avoid any ambiguity, use of these terms should be applied with caution. The term tar is usually applied to the volatile and nonvolatile soluble products that are produced during the carbonization or destructive distillation (thermal decomposition with the simultaneous removal of distillate) of various organic materials. By way of further definition, distillation of the tar yields an oil (volatile organic products often referred to as benzole) and a nonvolatile pitch. In addition, the origin of the... 

Berthollet s name chemical mass was used by E. G. Fischer L. Sigwart used the name chemical moment (chemische Moment). Karsten gave a good account of Berthollet s theory and expressed the action of mass by formulae. If a substance A acts on the substances B, C, D, E, and the chemical masses of the latter are w, w, 0, />, the proportions of A taken by them are m/Z, njE, ojE, nApJEy where E=m -n-]ro Karsten published several other memoirs on mass action. Berthollet s law of mass action was favourably received by Davy and Berzelius, both of whom pointed out that it is not in contradiction to the law of definite proportions. Berzelius thought it necessary to add the proposition that when two dissolved salts can produce only soluble products, the strongest acid takes the strongest base and leaves the weak base to the weak acid. ... 

Gay-Lussac had determined the solubilities of several salts in water at different temperatures and plotted solubility curves. He recognised that the solubility is definite at a given temperature in presence of the solid salt (toujours en contact avec le sel). He noticed the break in the solubility curve of Glauber s salt (Na2S04,ioH20) and that this occurs at a maximum of solubility, but he did not explain this as due to the formation of a new solid phase (Na2S04). This was stated independently by Kopp and by Berzelius. The production of crystalline anhydrous sodium sulphate from hot solutions of Glauber s salt had, however, been described by Thomson in 1826. ... 

Is called the solubility product of the salt. (It should be noted that it IS not customary to extend this definition to hydrated salts, but there is no reason why they should be excluded.) Values of the solubility product are often given on mole fraction or concentration scales. In dilute solutions, the theoretical behaviour of the activity coefficients as a function of ionic strength is often sufficiently well known that reliable extrapolations to infinite dilution can be made, and values of Kg can be determined. In more concentrated solutions, the same problems with activity coefficients that were outlined in the section on variation of solubility with temperature still occur. If these complications do not arise, the solubility of a hydrate salt CvAv nH20 in the presence of other solutes is given by eqn [SO] as... 

Definitions. Define and illustrate briefly (a) pH, (b) acidic solution, (c) basic solution, (d) conservation condition, (e) electrical neutrality condition, (f) common-ion efiect, (g) bufiFer solution, (h) solubility product. 

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