What is the solubility-product expression for the equilibrium established when calcium phosphate, ca3(po4)2(s), is added to pure water at 25°c?

Ks = [Ca2+]^3 . [PO4 3+]^2

Ks (solubility product) is the product of calcium ion concentration multiplied by phosphate ion concentration

Explanation: when a salt is added to water it dissolves and the molecules dissociates into ions. It can be represented in the equation:

Ca3(PO4)2(s) <--> 3Ca2+ (aq) + 2PO4 3+ (aq)

Where s and aq indicate the state in which the molecule is. S for solid and aq for aqueous.

This solution reach and equilibrium, that means that salt is dissociated at the same rate that ions reunite to form a molecule.

In chemical equilibrium there is a constant that reflects this rate and is generally expressed as: K = [D]^d .[C]^c/ [A]^a .[B]^b

D, C represent products and A, B reagents. Lower case letters are the stoichiometric coefficients.

Another thing to remind is that only gases and aqueous molecules are taking into account in the constant, solids and liquids do not affect it and values are replace in the equation by 1.

Now, Ca3(PO4)2 is in solid state so it doesn't affect Ks, in that case only concentrations of Ca and PO4 are useful. Since these ions are products, the expression of Ks is

Ks= [Ca2+]^3 . [PO4 3+]^2

if the concentration of products is decreased, the equilibrium will shift toward the products). add an inert gas (one that is not involved in the reaction) to the constant-volume reaction mixture: this will increase the total pressure of the system, but will have no effect on the equilibrium condition.

explanation:

increased stability in the completion of fluorine's outer shell.