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What is the freezing point of an aqueous solution that boils at 106.5 °C?
Ch.13 - Solutions
Chapter 13, Problem 113
A solution is prepared from 4.5701 g of magnesium chloride and 43.238 g of water. The vapor pressure of water above this solution is 0.3624 atm at 348.0 K. The vapor pressure of pure water at this temperature is 0.3804 atm. What is the value of the van’t Hoff factor (i) for magnesium chloride in this solution?
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Calculate the molality of the solution by first determining the moles of magnesium chloride (MgCl_2) using its molar mass.
Determine the molality (m) of the solution using the formula: \( m = \frac{\text{moles of solute}}{\text{kilograms of solvent}} \).
Use Raoult's Law to find the expected vapor pressure of the solution: \( P_{solution} = X_{solvent} \times P^0_{solvent} \), where \( X_{solvent} \) is the mole fraction of the solvent.
Calculate the mole fraction of the solvent (water) using the formula: \( X_{solvent} = \frac{\text{moles of solvent}}{\text{moles of solvent} + i \times \text{moles of solute}} \).
Rearrange the equation from Raoult's Law to solve for the van’t Hoff factor \( i \) using the given vapor pressures and the calculated mole fraction.
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