How does non-ideal solution affect the process of distillation?

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Liya9182002
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Can anyone give me a specific explanation for this?
Can you also explain the overall application of Raoult's law in distillation?
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charco
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Raoult's law says that the total vapour pressure is proportional to the sum of the vapour pressures of the individual components of a liquid mixture, and that the vapour pressure of the individual components is equal to the pure vapour pressure x the mole fraction of the component.

This leads to a straight line on a graph for total vapour pressure against % composion of the two components.

Non-ideality is caused by interaction between the particles of each component which creates deviation from Raoult's law and the vapour pressure/composition straight line becomes curved, either up or down, depending on the type of interparticular interactions.

This may create a maximum in the vapour pressure curve, which prevents separation of the two components by fractional distillation, as the % composition at this point will have a boiling point minimum and produce a constant boiling mixture called an azeotrope.

One example of this occurs in mixtures of ethanol and water, where the azeotrope has 95.63% ethanol and 4.37% water. This mixture boils at 78.2ºC under atmospheric pressure and produces a vapour with exactly the same compostion, meaning that fractional distillation cannot separate it.
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