Chapter 21, Problem 80GQ

Interpretation Introduction

Interpretation:

To calculate the mass of ${\text{CaF}}_{\text{2}}$ must use for $1\times {10}^6\text{L}$ of water.

Concept introduction:

Solubility product constant $\left(K_{\text{sp}}\right)$ is equilibrium constant is defined for equilibrium between a solid and its respective ions in a solution.

The ionization of ${\text{CaF}}_{\text{2}}$ in water is written as,

    ${\text{CaF}}_{\text{2}}\left(\text{s}\right)\rightleftharpoons {\text{Ca}}^{\text{+2}}\left(\text{aq}\right)+2{\text{F}}^{-}\left(\text{aq}\right)$

The Solubility product constant $\left(K_{\text{sp}}\right)$ for ${\text{CaF}}_{\text{2}}$ is written as,

$K_{\text{sp}}=\left[{\text{Ca}}^{\text{+2}}\right]{\left[2\left({\text{F}}^{-}\right)\right]}^2$ (1)

$\begin{array}{l}\text{Number}\text{of}\text{moles}\text{=}\frac{\text{Mass}}{\text{Molecular}\text{mass}}\\ \text{Mass}\text{=}\text{Number}\text{of}\text{moles}\text{×}\text{Molecular}\text{mass}\end{array}$