Chapter 13, Problem 81GQ

(a)

Interpretation Introduction

Interpretation: van’t Hoff factor of $2\%of{H}_{2}S{O}_4$ has to be determined.

Concept introduction:

Colligative properties: Properties of solutions which having influence on the concentration of the solute in it. Colligative properties are,

• Decrease in the vapor pressure
• Increase in the boiling point
• Decline in the freezing point
• Osmotic pressure

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

$\begin{array}{c}\text{Freezing point depression = }\Delta {\text{T}}_{fp}{\text{= K}}_{fp}{\text{. m}}_{solute}\text{.i,}\\ \text{where,}{\text{K}}_{fp}\text{=}\text{molal freezing point depression constant,}\\ {\text{m}}_{solute}\text{= molality of solute,}\\ \text{i}\text{=}\text{van't}\text{Hoff}\text{factor}\text{.}\end{array}$

van’t Hoff factor, i: it is the ration between change in in freezing point measured and change in in freezing point calculated. It indicates the total number of ions that are produced.

Molality (m): Molality is the number of moles of solute present in one kilogram of solvent.

  $\text{Molality (m) =}\frac{\text{Number}\text{of}\text{moles}\text{of}\text{solute}}{\text{1kg}\text{of}\text{solvent}}$

The number of moles of any substance can be determined using the equation

  $\text{Number}\text{of}\text{mole}\text{=}\frac{\text{Given}\text{mass}\text{of}\text{the}\text{substance}}{\text{Molar}\text{mass}}$

(b)

Interpretation Introduction

Interpretation: From the following, the best represents that $H_{2}S{O}_4$ is in a dilute aqueous solution has to be identified

Concept introduction:

Colligative properties: Properties of solutions which having influence on the concentration of the solute in it. Colligative properties are,

• Decrease in the vapor pressure
• Increase in the boiling point
• Decline in the freezing point
• Osmotic pressure