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Solutions — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistrySolutions2 Marks
Question
Non-ideal solutions exhibit either positive or negative deviations from Raoult’s law. What are these deviations and why are they caused? Explain with one example for each type.
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Answer

When the vapour pressure of a non-ideal solution is either higher or lower than that predicted by Raoult’s law, the solution exhibits deviations. These deviations are caused because of unequal intermolecular attractive forces between solute-solvent molecules and solute-solute or solvent-solvent molecules. Positive deviation eg: Mixture of ethanol and acetone, Carbon-disulphide and acetone. Negative deviation eg: Chloroform and acetone, nitric acid and water.

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