Chapter 16, Problem 93A

Interpretation Introduction

Interpretation: The reason for the faster melting of ice when the solute is added is calcium chloride than sodium chloride is to be determined.

Concept introduction: Depression in freezing point is a term associated with the decrease in the value of the freezing point of solvents by the addition of solute molecules. The addition of solute particles to a solvent will reduce the freezing point of that corresponding solvent.

Answer to Problem 93A

The dissociation of calcium chloride results in the formation of three ions is the reason for its effective melting of ice than sodium chloride.

Explanation of Solution

The addition of solute particles reduces the freezing point of the corresponding solvent.

Calcium chloride, ${\text{ CaCl}}_2$ dissociates into three ions,

  ${\text{ CaCl}}_2\to C{a}_2+2C{l}^{-}$

While, the dissociation of $\text{ NaCl}$ is,

  $\text{ NaCl}\to {\text{Na+Cl}}^{-}$

So, only two ions are produced.

The dissociation of calcium chloride produces three ions is the reason for the effective melting of ice by reducing the freezing point of water.