Chapter 5, Problem 5F.5BST

Interpretation Introduction

Interpretation:

The osmotic pressure of $\text{1}\text{.50}\text{g}$ polymethyl methacrylate dissolved in enough methylbenzene produces $\text{175}\text{mL}$ of solution is $\text{2}\text{.11}\text{kPa}$ at ${\text{20}}^{\text{°}}\text{C}$.  The average molar mass of sample of polymethyl methacrylate has to be calculated.

Concept Introduction:

By using the Osmometric method, the molar mass of solute can be calculated as follows:

Step-1: The observed osmotic pressure has to be converted into solute molar concentration, $\text{c}$ in the form of

  $\text{c}\text{=}\frac{\text{Π}}{\text{iRT}}$

Step-2: The amount of solute (in moles) in the solution is calculated by multiplying the molar concentration of solute by the volume of solution.

  ${\text{n}}_{\text{solute}}\text{=}{\text{c}}_{\text{solute}}\text{×}\text{V}$

Step-3: The molar mass of the solute is calculated by dividing the given mass of solute (in grams) by the calculated amount in moles.

  ${\text{M}}_{\text{solute}}\text{=}\frac{{\text{m}}_{\text{solute}}}{{\text{n}}_{\text{solute}}}$