Purchase Solution

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

Not what you're looking for?

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?

##### 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.

##### Solution Preview

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
***********

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 provided by:
• BSc (Hons),
• MSc,
• PhD,
###### Recent Feedback
• "Thankyou for the feedback. I have a few question though; With the first statistic about cost below... “According to Sigma-Aldrich catalog, cost of 1L octane is AUD \$ 392.00, whereas the cost of 1L ethanol is AUD \$196.00. Moreover, if ethanol is obtained from sugar industry as a by-product, it may cost even less. Source of oxygen is ambient atmosphere, so it costs nothing. So ethanol is much cheaper than petrol, in fact it is half-priced: AUD \$ (392-196) = \$ 196.” I didn't think it made sense because the cost of petrol per litre is normally a dollar something or even less than a dollar not a couple of hundred of dollars. For example, a statistic that I found in america was: "U.S. ethanol production costs are about \$1.20 per gallon of ethanol, or \$1.82 per gallon on a gasoline-equivalent basis." However, I was wondering whether you could find an Australian statistic. Also, you mentioned that H20 is not a greenhouse gas. However, in the combustion equations it is actually carbon dioxide and water vapour which are produced and they are both greenhouse gases. Finally, how do I calculate the energy efficiency of ethanol and petrol? "
• "Thank you!"
• "Didnt really answer my questions but gave me a start at least."
• "Once again this is tremendous help I can't thank you enough for not only working the problem but explaining in detail how and why!! KR"
• "Awesome thank you so much for the help!!!"

##### Functional groups in Organic Chemistry

You will be tested on the names of functional groups in Organic Chemistry. It is very important to know the functional groups to understand Organic reactions.

##### General Chemistry - Classification of Matter

This test will assess your knowledge on the classification of matter which includes elements, compounds and mixtures.

##### Match Elements with their Symbols

Elements are provided: choose the matching one- or two-letter symbol for each element.

##### Thermochemistry

The quiz helps in revising basic concepts about thermochemistry.