Question

At a certain temperature, the solubility of strontium arsenate, Sr3(AsO4)2 is 0.0620 g/L what is the Ksp of this salt at this temperature?
(the Ksp of the salt is equal to the square of the molar concentration. convert g/L to mol/L before plugging into Ksp expression)
Ksp=?

Answer 1

Concepts and reason

Calculate the concentration of the strontium and the arsenate ions from the dissociation reaction for the salt, the calculate the solubility product.

Fundamentals

The solubility product of a salt is a measure of the solubility of a salt in water at a given temperature. The solubility product is the equilibrium constant for a salt that is partially soluble in water such that an equilibrium exists between the solid salt and the dissociated ions.

A salt dissociates in water as follows:

The solubility product for this salt is given as follows:

Here, is the solubility product, and is the solubility of the ions, in , raised to the power of the coefficient of the ions.

Note that has no units, because the quantities used in the expression for equilibrium constants are activities of the ions, and for a dilute solution activity of the ion is considered to be equal to the concentration of the ions.

The concentration of the strontium arsenate solution is .

When strontium arsenate is dissolved in water, it dissociates as follows:

Solubility product () for this reaction is . Here, s is the solubility.

The solubility product for this reaction is

Ans:

The solubility product for this reaction is