Chapter 13, Problem 33PS

(a)

Interpretation Introduction

Interpretation: The molality of the ethanol in a mixture of ethanol and water has to be identified.

Concept introduction:

Freezing point depression: The freezing point of the solution varies with the solute concentration.

$\begin{array}{l}\text{Depression}{\text{ in Freezing point = ΔT}}_{\text{fp}}{\text{= K}}_{\text{fp}}{\text{. m}}_{\text{solute}}\text{,}\\ \text{where,}{\text{K}}_{\text{fp}}\text{is}\text{molal freezing point depression constant,}\\ {\text{m}}_{\text{solute}}\text{is molality of solute}\text{. }\end{array}$

Weight percent: The mass of one component divided by the total mass of the mixture, multiplied by $100\%$

$\text{weight \% A = }\frac{\text{Mass of A}}{\text{ Mass of A + Mass of B + Mass of C + }\mathrm{...}}\text{×100\%}$

(b)

Interpretation Introduction

Interpretation: The weight percentage of the ethanol in a mixture of ethanol and water has to be identified.

Concept introduction:

Weight percent: The mass of one component divided by the total mass of the mixture, multiplied by $100\%$

$\text{weight \% A = }\frac{\text{Mass of A}}{\text{ Mass of A + Mass of B + Mass of C + }\mathrm{...}}\text{×100\%}$