Solubility and Solubility Product

Table 1. Solubility and Solubility Products of Silver(I) Compounds...

Sulfides with widely different solubilities and solubility products can be selectively precipitated by adding S2 ions to the solution removed from the chlorides in the first step (see Fig. 11.20). Some metal sulfides (such as CuS, HgS, and Sb2S3) have extremely small solubility products and precipitate if there is the merest trace of S2" ions in the solution. Such a very low concentration of S2 ions is achieved by adding hydrogen sulfide, H2S, to an acidified solution. A higher hydronium ion concentration shifts the equilibrium... 

One of the most basic requirements in analytical chemistry is the ability to make up solutions to the required strength, and to be able to interpret the various ways of defining concentration in solution and solids. For solution-based methods, it is vital to be able to accurately prepare known-strength solutions in order to calibrate analytical instruments. By way of background to this, we introduce some elementary chemical thermodynamics - the equilibrium constant of a reversible reaction, and the solubility and solubility product of compounds. More information, and considerably more detail, on this topic can be found in Garrels and Christ (1965), as well as many more recent geochemistry texts. We then give some worked examples to show how... 

Distinguish between the terms solubility and solubility product constant. ... 

Moeller et al. [294, 295] have thoroughly studied the pH values at which the rare earth hydroxides are precipitated from various salt solutions, and also the solubility and solubility product constants of the hydroxides. Their results are summarized in Table 18. 

Y" j Stephen J. Hawkes, "What vJ Should We Teach Beginners about Solubility and Solubility Product " ]. Chem. Educ., Vol. 75, 1998,1179-1181. 

The solubility and solubility product constants, X, for many silver compounds are given in Table 1 (7—9). 

Solubility, Molar Solubility, and Solubility Product Expression... 

As the above examples show, solubility and solubility product are related. If we know one, we can calculate the other, but each quantity provides different information. Table 16.3 shows the relationship between molar solubility and solubility product for a number of ionic compounds. 

Molar solubility, solubility, and solubility product all refer to a saturated solution. 

KOL] Kolthoff, I. M., The solubilities and solubility products of metallic sulfides in water, J. Phys. Chem., 35, (1931), 2711-2721. Cited on pages 180,263. 

Hawkes, SJ. (1998). What should we teach beginners about solubility and solubility products Journal of Chemical Education, 75, 1179-1181. 

Quantitative Relationship Between Solubility and Solubility Product... 

Use BaS04 to distinguish between solubility, molar solubility, and solubility product. 

A detailed study of the RF3, R = La-Lu, exc. Pm, behavior in aqueous solutions was completed by Menon and James (1989). Solubilities and solubility products were determined by conductometric, potentiometric, and radiometric techniques as a function of pH. Stability constants for the mono- and difluorocomplexes in aqueous solution were also measured. The effect of precipitate aging was considered for Dyp3. Solubilities and pfC p values of the RF3 do not vary systematically with atomic number, but instead remain relatively constant, varying by no more than three units across the series, with values of 15.2 for Lap3 and 14.4 for LUF3. 

EXAMPLE 20-2 Molar Solubility and Solubility Product Constant... 

Define solubility, molar solubility, and solubility product. Explain the difference between solubility and the solubility product of a slightly soluble substance such as BaS04. 

Solubility and solubility product must not be confused with each other. The solubility of a salt is the quantity present in a unit amount of a saturated solution, expressed in moles per liter, grams per 100 ml, or other units. The solubility depends on what else is in the solution. The solubility product, being an equilibrium constant, depends only on temperature. There is a connection, of course, between the solubility and the solubility product if one is known, the other can be calculated. 

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