Question

Write the ksp expression for the sparingly soluble compound zinc phosphate, zn3(po4)2.

Answer 1

The give compound is a sparingly soluble salt, $Zn_{3}(PO_{4})_{2}$. The solubility equilibrium for this compound can be represented as:

                 $Zn_{3}(PO_{4})_{2}(aq)<==>3Zn^{2+}(aq)+2PO_{4}^{3-}(aq)$

Initial(M)                      -                            0                   0

Change(M)                 -                          +3x                +2x

Equilibrium(M)            -                           3x                  2x

Solubility product expression for this equilibrium will be:

$K_{sp}=[Zn^{2+}]^{3}[PO_{4}^{3-}]^{2}$

              = $(3x)^{3}(2x)^{2}=108x^{5}$

Where x will be the molar solubility of the compound$Zn_{3}(PO_{4})_{2}$at that given temperature.