explain how the minimum boiling azeotrope shows the positive deviation from raoult's law briefly

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Solution

Dear Student

In positive deviation from Raoult's Law, intermolecular interaction of molecule A to molecule B is less than intermolecular interaction between molecule A and molecule A or between molecule B and molecule B.
Thus, when A is added to B, they break some the interactions of molecule B and molecule B. This increases the vapour pressure and since there are less nteractions to overcome, boiling point of the azeotrope decreases than the pure.

Eg:
when cyclohexane is added to ethanol, cyclohexane break some of the hydrogen bonding among the ethanol molecule and increases the vapour pressure(positive deviation) and due to less H-bonding now, boiling point also decreases (less heat required to overcome less no. of interactions.)

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On the basis of information given below mark the correct option. Information On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.
(a) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult's law
(b) At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show positive deviation from Raoult's law
(c) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult's law
(d) At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show negative deviation from Raoult's law

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