How does adding a non-volatile solute like sucrose affect the boiling point and freezing point of water?
Answer and explanation
Correct answer: C. Boiling point elevates and freezing point depresses, proportional to solute molality
- Step 1: Solute particles lower the solvent's chemical potential and vapor pressure. Step 2. Lower vapor pressure requires higher temperature to reach atmospheric pressure (boiling point elevation Delta T_b = K_b m). Answer: Boiling point elevates and freezing point depresses, proportional to solute molality. Why not the others: Lower chemical potential stabilizes the liquid phase, requiring lower temperature to freeze (Delta T_f = K_f m).
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