Question

The solubility of $C{a}_3(P{O}_4{)}_2$ in water is y moles / litre. Its solubility product is

• A. $6y^4$
• B. $36y^4$
• C. $64y^5$
• D. $108y^5$

Answer 1

Answer: (D)

$C{a}_3(P{O}_4{)}_2(s)\rightleftharpoons \underset{\text{3y}}{3C{a}^{2+}}(aq)+\underset{\text{2y}}{2P{O}_4^{3-}}(aq)$
$\therefore K_{sp}={\left[C{a}^{2+}\right]}^3\cdot {\left[P{O}_4^{3-}\right]}^2$
$={\left(3y\right)}^3\cdot {\left(2y\right)}^2$
$=27y^3\times 4y^2$
$=108y^5$