Relationship Between Solubility and Ksp

Is there a relationship between the solubility product constant, K p, of a solute and the solute s molar solubility—its molarity in a saturated aqueous solution As shown in Examples 18-2 and 18-3, there is a definite relationship between them. As discussed in Section 18-4, calculations involving Kgp are generally more subject to error than are those involving other equilibrium constants, but the results are suitable for many purposes. In Example 18-2, we start with an experimentally determined solubility and obtain a value of Xgp. 

The inverse of Example 18-2 is the calculation of the solubility of a solute from its fCgp value. When this is done, as in Example 18-3, the result is always a molar solubility—a molarity. Additional conversions are required to obtain solubility in units other than moles per liter, as in Practice Example 18-3B. 

EXAMPLE 18-2 Calculating of a Slightly Soluble Solute from Its Solubility 

We need to construct a conversion pathway that begins with finding [Ca ] and [S04 ], which we can then substitute into the K p expression. 

The first step is to convert the mass of CaS04 in a 100 mL volume to molar solubility. This is accomplished by using the inverse of the molar mass of CaS04 and replacing 100 mL with 0.100 L. 

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Solubility Product Constant, Kjp 18-2 Relationship Between Solubility and Ksp... 

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