SolutionsI: LiquidLiquid2 - PowerPoint PPT Presentation

Title: SolutionsI: LiquidLiquid2


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Solutions(I) Liquid-Liquid(2)

• Lecture Note 16
• Physical Chemistry II, 2008
• KAIST

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Nonideality of the solution is described by
activity coefficients
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Activity for nonideal solution, fugacity for
nonideal gas

• Chemical potentials for nonideal solution may be
  given by
• Remember

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Activity and activity coefficient

• Activity of component 1 from empirical expression
• Activity coefficient measure of nonideality (1,
  ideal)
• Activity is related to chemical potential
  activities of the two components of a binary
  mixture are dependent on each other
• If a1 x1 for all x1 (ideal), a2 x2

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Similar to the µ -gt P case
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Two component mixture 1) Two components are
miscible at all proportions (Raoults law Std S)
2) Sparingly miscible mixture (Henrys
law Std S)
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Numerical values of activity and activity
coefficient depend on standard states
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xj1, aj1
xj1, aj?1
Raoults law activity is more convenient for L-L
solutions Henrys law activity is appropriate for
non-liquid solute
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These can be used to calculate Henrys
law activity at x-gt 1
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Nonidelaity accounted for by activity coefficients
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Regular solutions satisfy Eq.(24.47)
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Mixing Gibbs E change at different T (given in
unit of RT/?) This plot applies to any regular
solution (for the top curve, more negative Gibbs
E can be obtained by having two phases)
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One solution
Two Immiscible solutions
This plot applicable to all regular solutions
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Excess Gibbs energy of mixing is another measure
of nonideality
Curve for this not shown
x1x2x1(1-x1)
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Nonsymmetry of graph indicates nonzero ß