Which of the following is true of the solubility product constant?
A. It is the product of the initial concentrations of the ions in a solution.
B. It is an equilibrium constant.
C. It is an equilibrium position.
D. Its value changes in the presence of a common ion.
B ... It's an equilibrium constant that defines the 'extent' of reaction. Caution: Ksp is often used to compare solubility of two salts. This is true only if the ionization ratios of the two salts are identical. If they are not, you'll need to calculate the actual solubility before comparing. For 1:1 ionzn ratio S = SqrRt(Ksp); 2:1 or 1:2 ration S = CubeRt(Ksp/4); 3:1 or 1:3 S = FourthRt(Ksp/27); 4:1 or 1:4 S = FifthRt(Ksp/256) and 2:3 or 3:2 S = FifthRt(Ksp/108).
A is incorrect b/c initial concentrations need to be raised to the power of the respective coefficients in the balanced net ionic equation.
C is incorrect b/c there is no such thing as an 'equilibrium position'
D is incorrect b/c the presence of a common ion only decreases solubility but does not change the Ksp value so long as temperature remains constant.
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The correct answer is B. It is an equilibrium constant.
The solubility product constant (Ksp) is a value that represents the extent to which a sparingly soluble salt dissolves in a solvent, usually water. It is a special type of equilibrium constant that describes the equilibrium between the dissolved ions and the undissolved solid in a saturated solution.
To determine the solubility product constant, you need to know the balanced chemical equation for the dissolution of the salt and the concentrations of the ions in the saturated solution.
The general form of a solubility product expression is:
Ksp = [A+]^m [B-]^n
Where [A+] is the concentration of the cation A+ and [B-] is the concentration of the anion B-. The exponents m and n are the coefficients of the ions in the balanced chemical equation.
The solubility product constant depends only on temperature and is specific to a particular salt. It does not depend on the initial concentrations of the ions or the presence of other ions in the solution.
The value of Ksp indicates the degree of dissociation of the salt. A higher value of Ksp means a greater extent of dissolution of the salt and a more soluble compound. Conversely, a lower value of Ksp means a lower solubility and a less soluble compound.
In the presence of a common ion, the solubility and solubility product constant of a salt is affected. The common ion effect, also known as ion suppression, reduces the solubility of a salt when a common ion is added to the solution. This happens because the increase in concentration of the common ion shifts the equilibrium towards the formation of the undissolved solid, reducing the solubility of the salt.
To summarize, the solubility product constant is an equilibrium constant that describes the equilibrium between the dissolved ions and the undissolved solid in a saturated solution. Its value depends only on temperature and is specific to a particular salt.