# Problem: A solution contains 5.00 g of urea, CO(NH2)2, a nonvolatile compound, dissolved in 0.100 kg of water. If the vapor pressure of pure water at 25 °C is 23.7 torr, what is the vapor pressure of the solution?

###### FREE Expert Solution

Vapor Pressure Lowering is a colligative property which describes the decrease in vapor pressure of a solution when a solute is added to a solution.

The formula for vapor pressure lowering is:

$\overline{){{\mathbf{P}}}_{{\mathbf{solution}}}{\mathbf{=}}{{\mathbf{\chi }}}_{{\mathbf{solvent}}}{\mathbf{·}}{\mathbf{P}}{{\mathbf{°}}}_{{\mathbf{solvent}}}}$

Where:

Psolution is the vapor pressure of the solution

solvent is the vapor pressure of pure solvent

Xsolvent is the mole fraction of the solvent

Solve for the mole fraction of the solvent:

$\overline{){{\mathbf{\chi }}}_{{\mathbf{solvent}}}{\mathbf{=}}\frac{{\mathbf{mol}}_{\mathbf{solvent}}}{\mathbf{\iota }\mathbf{·}{\mathbf{mol}}_{\mathbf{solute}}\mathbf{+}{\mathbf{mol}}_{\mathbf{solvent}}}}$

Moles of solute (urea):

0.083 moles

Moles solvent (water):

Recall: 1 kg = 103 g

5.55 moles

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###### Problem Details

A solution contains 5.00 g of urea, CO(NH2)2, a nonvolatile compound, dissolved in 0.100 kg of water. If the vapor pressure of pure water at 25 °C is 23.7 torr, what is the vapor pressure of the solution?