Chapter 17, Problem 70A

Interpretation Introduction

Interpretation:

The solubility product of Ca₃(PO₄)₂ have to be calculated.

Concept Introduction:

Solubility product: When a sparingly soluble salt is dissolved in water, a very little amount of salt dissolves and rest of the salt remains as solid in the solution. In the solution of sparingly soluble salt, equilibrium exists between undissolved salt and the ions dissociated in the solution.

The solubility product of a sparingly soluble salt is calculated by multiplying the concentrations of the ions raised to a power equal to the number appearing in the balanced equation representing the dissociation of the electrolyte.

Answer to Problem 70A

The solubility product of Ca₃(PO₄)₂ is 1.28 × 10-32 M⁵.

Explanation of Solution

Data given: The solubility of Ca₃(PO₄)₂ at equilibrium S = 1.64 × 10-7 M

  $\begin{array}{l}C{a}_3{\left(P{O}_4\right)}_2(s,satd.soln.)\rightleftharpoons 3C{a}^{2+}(aq)+2P{O}_4{}^{3-}(aq)\\ $ K_{sp}={[C{a}^{2+}]}^3{[P{O}_4{}^{3-}]}^2$$ ={[3S]}^3{[2S]}^2=108S^5$$ =108\times {(1.64\times 10^{-7}M)}^5$$ =1.28\times 10^{-32}{M}^5$\end{array}$