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A solubility equilibrium exists when a chemical compound in the solid state is in chemical equilibrium with a solution containing the compound. This type of equilibrium is an example of dynamic equilibrium in that some individual molecules migrate between the solid and solution phases such that the rates of dissolution and precipitation are equal to one another.
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".
Solubility will also depend on the excess or deficiency of a common ion in the solution [clarification needed], a phenomenon known as the common-ion effect. To a lesser extent, solubility will depend on the ionic strength of solutions. The last two effects can be quantified using the equation for solubility equilibrium.
In chemistry, the common-ion effect refers to the decrease in solubility of an ionic precipitate by the addition to the solution of a soluble compound with an ion in common with the precipitate. [1] This behaviour is a consequence of Le Chatelier's principle for the equilibrium reaction of the ionic association / dissociation .
Calcium hydroxide is modestly soluble in water, as seen for many dihydroxides. Its solubility increases from 0.66 g/L at 100 °C to 1.89 g/L at 0 °C. [8] Its solubility product K sp of 5.02 × 10 −6 at 25 °C, [1] its dissociation in water is large enough that its solutions are basic according to the following dissolution reaction:
The thermodynamic equilibrium constant, K ⊖, for the equilibrium + can be defined [15] as = {} {} {} where {ML} is the activity of the chemical species ML etc. K ⊖ is dimensionless since activity is dimensionless. Activities of the products are placed in the numerator, activities of the reactants are placed in the denominator.
Calcium carbonate saturation can be determined using the following equation: Ω = ([Ca 2+][CO 3 2−])/K sp. where the numerator ([Ca 2+][CO 3 2−]) denotes the concentration of calcium and carbonate ions and the denominator (K sp) refers to the mineral (solid) phase stoichiometric solubility product of calcium carbonate. [8]
(However, PE only dissolves at temperatures well above 100 °C.) Poly(styrene) has a solubility parameter of 9.1 cal 1/2 cm −3/2, and thus ethyl acetate is likely to be a good solvent. Nylon 6,6 has a solubility parameter of 13.7 cal 1/2 cm −3/2, and ethanol is likely to be the best solvent of those tabulated. However, the latter is polar ...