Chapter 16, Problem 65AE

Interpretation Introduction

Interpretation:

Among compounds ${\text{BaSO}}_4$ and ${\text{SrSO}}_4$ that forms precipitate has to be calculated.

Concept Introduction:

The equilibrium constant used for the partially soluble salt in water is termed as solubility product constant $K_{\text{sp}}$. Consider solubility of $\text{AB}$ in water and equilibrium equation of $\text{AB}$ is as follows:

  $\text{AB}\left(s\right)\rightleftharpoons {\text{A}}^{+}\left(aq\right)+{\text{B}}^{-}\left(aq\right)$

The expression for $K_{\text{sp}}$ is as follows:

  $K_{\text{sp}}=\frac{\left[{\text{A}}^{+}\right]\left[{\text{B}}^{-}\right]}{\left[\text{AB}\left(s\right)\right]}$

Generally the concentration of solid is taken as constant. Therefore the expression for $K_{\text{sp}}$ of $\text{AB}$ is as follows:

  $K_{\text{sp}}=\left[{\text{A}}^{+}\right]\left[{\text{B}}^{-}\right]$

Equilibrium quotient is denoted with $\text{Q}$ and is product of concentration of ions raised to proper power of new molecule formed by mixture of two molecules. It tells two major points that are as follows:

  $\begin{array}{l}\text{Q}>K_{s\text{p}}\text{ precipitation occurs}\\ \text{Q}<K_{s\text{p}}\text{ no precipitation}\end{array}$