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Ch.13 - Solutions
Chapter 13, Problem 11

What is the boiling point of an aqueous solution with a vapor pressure of 20.5 torr at 25 °C? (Assume a nonvolatile solute.)

Verified step by step guidance
1
Identify that the problem involves finding the boiling point of a solution, which requires understanding the colligative properties of solutions.
Recognize that the vapor pressure of the solution is given as 20.5 torr at 25 °C, and the normal boiling point of water is 100 °C with a vapor pressure of 760 torr.
Use Raoult's Law to relate the vapor pressure of the solution to the mole fraction of the solvent: P_solution = X_solvent * P_pure solvent.
Since the solute is nonvolatile, the vapor pressure lowering can be used to find the boiling point elevation: ΔT_b = i * K_b * m, where i is the van't Hoff factor, K_b is the ebullioscopic constant, and m is the molality.
Calculate the boiling point of the solution by adding the boiling point elevation (ΔT_b) to the normal boiling point of the pure solvent (100 °C).