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# Vapor Pressure of Mixtures of Miscible vs. Immiscible Liquids: Physical Significance

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Consider a physical explanation for the difference of vapour pressure of miscible and immiscible solutions. For immiscible the total vapour pressure is equal to the sum of the pressure from the pure liquids but and miscible liquids pressure vapour pressure follows raoults law. What is the physical justification for this?

https://brainmass.com/chemistry/energetics-and-thermodynamics/vapor-pressure-mixtures-miscible-versus-immiscible-liquids-566911

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Physical explanation of difference between miscible and immiscible liquids vapour pressure
I wondered about a physical explanation for the difference of vapour pressure of miscible and immiscible solutions. For immiscible the total vapour pressure is equal to the sum of the pressure from the pure liquids but and miscible liquids pressure vapour pressure follows Raoults law. What is the physical justification for this? Question is a little bit further illustrated in the attachment.
PS: If you know about a physical justification from a book or something I will be very happy if the answer was just this text.
I only want an answer given in computer signs. If you think this is additional work let me know and I can add 2 credits
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Vapor Pressure of Miscible Liquids

Raoult's law states that for a mixture of miscible liquids,

"The partial vapor pressure of a component in a mixture is equal to the vapor pressure of the pure component at that temperature multiplied by its mole fraction in the mixture."

Raoult's Law only works for ideal mixtures.
In equation form, for a mixture of liquids A and B, this reads:

In this equation, PA and PB are the partial vapor pressures of the components A and B.
The total vapor pressure of the mixture is equal to the sum of the individual partial pressures.

The Po values are the vapor pressures of A and B if they were on their own as pure liquids. xA and xB are the mole fractions of A and B.

Physical significance of Raoult's law (for miscible liquids)

Remember, Raoult's law holds true for ideal mixtures only.
Examples of ideal mixtures:
There is ...

#### Solution Summary

This solution clarifies the basic concepts, related to vapor pressures of mixtures of miscible vs. immiscible liquids, in a lucid understandable manner along with diagrams and equations.

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