Chapter 17, Problem 99GQ

Interpretation Introduction

Interpretation:

Percentage of calcium ions removed from the hard water containing ${\text{Ca}}^{2+}$ ions by adding soda ash ${\text{Na}}_2{\text{CO}}_3$ in the water has to be calculated.

Concept introduction:

The solubility of a salt is defined as the maximum amount of salt that can be dissolved in definite amount of solvent. It is expressed in moles per liter or grams per liter. Solubility in terms of moles per liter is called molar solubility and is defined as the number of moles of solute (salt) dissolved in per liter of solution.

Solubility product constant $K_{\text{sp}}$ is an equilibrium constant and is defined as the product of the equilibrium concentration of the ions of the salt raised to the power of their coefficients in the balanced chemical equation.

The expression for $K_{\text{sp}}$ of a salt is given as,

$\begin{array}{l}{\text{A}}_x{\text{B}}_y\left(\text{s}\right)\rightleftharpoons x{\text{A}}^{y+}\left(\text{aq}\right)+y{\text{B}}^{-x}\left(\text{aq}\right)\\ K_{\text{sp}}={\left[{\text{A}}^{y+}\right]}^x{\left[{\text{B}}^{-x}\right]}^y\end{array}$