Slightly soluble ionic compounds molar solubility

For part (a), we write the appropriate chemical equations and solubility product expression, designate the equilibrium concentrations, and then substitute into the solubility product expression. For part (b), we recognize that NaF is a soluble ionic compound that is completely dissociated into its ions. MgF2 is a slightly soluble compound. Both compounds produce F ions so this is a common ion effect problem. We write the appropriate chemical equations and solubility product expression, represent the equilibrium concentrations, and substitute into the solubility product expression. For part (c), we compare the molar solubilities by calculating their ratio. 

Asp of slightly soluble ionic compounds Standard electrode potentials, i bgi(.ceii Standard free energies of formation, AG( Standard heats of formation, AJ7( Standard molar entropies, S°... 

The solubility product constant, K p, of a slightly soluble ionic compound is expressed in terms of the molar concentrations of ions in the saturated solution. These ion concentrations are in turn related to the molar solubility of the ionic compound, which is the moles of compound that dissolve to give a liter of saturated solution. The next two examples show how to determine the solubility product constant from the solubility of a slightly soluble ionic compound. 

Calculating the solubility of a slightly soluble salt in a solution of a common ion Given the solubility product constant, calculate the molar solubility of a slightly soluble ionic compound in a solution that contains a common ion. (EXAMPLE 18.5)... 

Limitations of the fCjp Concept—The solubility product concept is most useful for slightly soluble ionic solutes, and especially in cases where activities can be replaced by molar concentrations. Moderately or highly soluble ionic compounds require the use of activities. The presence of common ions reduces the solubility of a slightly soluble ionic solute, generally to a significant degree. 

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