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Questions and Answers
Explain the difference between ideal and non-ideal solutions in terms of molecular interactions.
Explain the difference between ideal and non-ideal solutions in terms of molecular interactions.
Ideal solutions have no interactions between molecules, while non-ideal solutions involve interactions between molecules.
What is the significance of ∆u in determining the behavior of solutions?
What is the significance of ∆u in determining the behavior of solutions?
∆u determines how solutions depart from ideality.
How does ∆H differ in ideal and non-ideal solutions?
How does ∆H differ in ideal and non-ideal solutions?
In non-ideal solutions, ∆H is approximately equal to ∆U, while in ideal solutions, there is no enthalpy change.
Describe positive deviations in solutions and their effect on mixing.
Describe positive deviations in solutions and their effect on mixing.
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What determines how solutions depart from ideality?
What determines how solutions depart from ideality?
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Explain the formula for ∆Gmix in non-ideal solutions.
Explain the formula for ∆Gmix in non-ideal solutions.
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What is the condition for a positive deviation from Raoult's Law?
What is the condition for a positive deviation from Raoult's Law?
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Explain why mixing acetone and chloroform results in a negative deviation from Raoult's Law.
Explain why mixing acetone and chloroform results in a negative deviation from Raoult's Law.
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What is the condition for an ideal dilute solution according to the text?
What is the condition for an ideal dilute solution according to the text?
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When does Henry's Law apply in the context of ideal dilute solutions?
When does Henry's Law apply in the context of ideal dilute solutions?
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What does the Henry's Law constant, KB, depend on?
What does the Henry's Law constant, KB, depend on?
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What is the consequence of a positive deviation in Henry's Law?
What is the consequence of a positive deviation in Henry's Law?
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Study Notes
Two-Component Phase Equilibria III
Ideal Solutions
- Free energy change in ideal solutions: ∆Gmix = nRT ( xA ln xA + xB ln xB )
- ∆Gmix is purely entropic, similar to gas mixtures
- No enthalpy change (∆Hmix = 0) and no volume change (∆Vmix = 0)
Non-Ideal Solutions
- Molecular interactions: uAA, uBB, and uAB determine the deviation from ideality
- ∆u = 2uAB - (uAA + uBB) determines how solutions depart from ideality
- Positive deviations: ∆u > 0, mixing is energetically not favorable
- Negative deviations: ∆u < 0, mixing is energetically favorable
Deviations from Raoult's Law
Positive Deviations
- Example: acetone and carbon disulphide
- ∆Gmix > ∆Gmix (ideal)
- Vapor pressure is higher than expected by Raoult's Law
Negative Deviations
- Example: acetone and chloroform
- ∆Gmix < ∆Gmix (ideal)
- Vapor pressure is lower than expected by Raoult's Law
Ideal Dilute Solutions and Henry's Law
Ideal Dilute Solution
- Defined by limits xB → 1 and xB → 0
- Raoult's Law applies for the solvent (xB → 1)
- Henry's Law applies for the solute (xB → 0)
Henry's Law
- pCS = xCS KCS
- KB is the Henry's Law constant, dependent on the solvent/solute mixture and temperature
- Positive deviation: KB > pB*
- Negative deviation: KB < pB*
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Description
Test your knowledge on Two-Component Phase Equilibria III, Ideal and Non-Ideal Solutions, and Free energy change in ideal solutions. Explore concepts related to ∆Gmix and its calculation in different liquid solutions.
