Solutions, Molarity and Intermolecular Forces Video Lessons

Concept: Solutions and Molarity.

# Problem: ​A solution contains 4.08 g of chloroform (CHCl3 ) and 9.29 g of acetone (CH3 COCH3 ). The vapor pressures at 35 oC of pure chloroform and pure acetone are 295 torr and 332 torr, respectively.What can you say about the relative strength of chloroform-acetone interactions compared to the acetone-acetone and chloroform-chloroform interactions?​

###### FREE Expert Solution

We’re asked to describe the relative strength of chloroform-acetone interactions compared to the acetone-acetone and chloroform-chloroform interactions by comparing the vapor pressure of each pure solvent to that of the solution.

We can compare the intermolecular forces or interactions between the molecules in the solution and pure solvent by solving for the vapor pressure of the solution.

The given solution is composed of chloroformCHCl3 and acetone,CH3COCH3 which are both volatile. For a solution with volatile solute and solvent, Raoult’s Law is given as:

$\overline{){{\mathbf{P}}}_{{\mathbf{solution}}}{\mathbf{=}}\mathbf{\left(}\mathbf{P}{\mathbf{°}}_{{\mathbf{CHCl}}_{\mathbf{3}}}{\mathbf{\chi }}_{{\mathbf{CHCl}}_{\mathbf{3}}}\mathbf{\right)}{\mathbf{+}}{\mathbf{\left(}}{\mathbf{P}}{{\mathbf{°}}}_{{\mathbf{CH}}_{\mathbf{3}}{\mathbf{COCH}}_{\mathbf{3}}}{{\mathbf{\chi }}}_{{\mathbf{CH}}_{\mathbf{3}}{\mathbf{COCH}}_{\mathbf{3}}}{\mathbf{\right)}}}$

where P˚ = vapor pressure of pure component and χ = mole fraction of component

Recall that the mole fraction is given by the equation:

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###### Problem Details

A solution contains 4.08 g of chloroform (CHCl3 ) and 9.29 g of acetone (CH3 COCH3 ). The vapor pressures at 35 oC of pure chloroform and pure acetone are 295 torr and 332 torr, respectively.

What can you say about the relative strength of chloroform-acetone interactions compared to the acetone-acetone and chloroform-chloroform interactions?