Question
Explain negative deviation from Raoult's law with an example.
✓
Answer
In case of negative deviation in the mixtures of two liquids A and B, the force of attraction between A-A an B-B is weaker than that between A-B. Due to this vapour pressure decreases.
Example: Mixture of phenol and aniline. In this situation the intermolecular hydrogen bond between the phenolic proton and the lone pair of electron of the nitrogen atom of aniline is stronger than the hydrogen bond between similar molecules.
Similarly, the mixture of chloroform and acetone also shows negative deviation from Raoult's law. This is because the chloroform forms hydrogen bond with acetone.
Example: Mixture of phenol and aniline. In this situation the intermolecular hydrogen bond between the phenolic proton and the lone pair of electron of the nitrogen atom of aniline is stronger than the hydrogen bond between similar molecules.
Similarly, the mixture of chloroform and acetone also shows negative deviation from Raoult's law. This is because the chloroform forms hydrogen bond with acetone.
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