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Question
Why does a solution containing non-volatile solute have higher boiling point than the pure solvent ?
Solution
Boiling point is the temperature at which the vapour pressure of a substance becomes equal to the atmospheric pressure. According to Raoult's law, the vapour pressure of a solvent decreases in the presence of a non-volatile solute. Thus, the vapour pressure of a solution containing a non-volatile solute requires a high temperature to become equal to the atmospheric pressure. That is why the boiling point of a solution containing a non-volatile solute increases. Thus, the solution containing a non-volatile solute has a higher boiling point than a pure solvent.
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