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Question
An azeotropic mixture of two liquids will have a boiling point lower than either of the two liquids when it ______.
Options
shows a negative deviation from Raoult’s law
forms an ideal solution
shows a positive deviation from Raoult’s law
is saturated
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Solution
An azeotropic mixture of two liquids will have a boiling point lower than either of the two liquids when it shows a positive deviation from Raoult’s law.
Explanation:
Intermolecular forces between solute and solvent are weaker than interactions between solute and solvent when a solution deviates from Raoult’s law. The total vapour pressure of the solution is greater than the total vapour pressure of an ideal solution. Furthermore, each component’s vapour pressure is greater than expected under Raoult’s law. As a result, the azeotropic mixture of two liquids boils at a lower temperature than either liquid alone.
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