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Chem 300 - Ch 24/#3 Today’s To Do List

Chem 300 - Ch 24/#3 Today’s To Do List. Critical behavior in L-L solutions Activity Excess Thermo Functions. T-x/y Plot. NonIdeal Solns Azeotropes. Extremes in Positive Deviations from RL: 2 Liquid Phases. The Lever Rule:.

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Chem 300 - Ch 24/#3 Today’s To Do List

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  1. Chem 300 - Ch 24/#3 Today’s To Do List • Critical behavior in L-L solutions • Activity • Excess Thermo Functions

  2. T-x/y Plot

  3. NonIdeal SolnsAzeotropes

  4. Extremes in Positive Deviations from RL: 2 Liquid Phases

  5. The Lever Rule: • Consider 2 phases (‘ & “) each containing 2 components (1 & 2) in equilibrium: • Let n’tot = n’1 + n’2 etc • n’tot/n”tot =(x”2 – x2)/(x2 – x’2) = (length)’’/(length)’

  6. C6H12/Nitrobenzene T-x 2-Phase Diagram

  7. H2O/Triethylamine T-x with Lower Critical Point

  8. H2O/Nicotine with upper & lower Critical T

  9. Activity: Measure of Soln Nonideality • dG = -SdT + VdP • 2 phases at const T and equilibrium • dGT = VdP  mjsoln= mjvap • mjsoln= mjvap = mjo(T) +RT ln Pj • If soln is ideal (RL holds): Pj = P*j xj • mjsoln= mjo(T) + RT ln P*j xj = mjo(T) + RT ln P*j + RT ln xj • mjsoln= mjo(T) + mj*(T) + RT ln xj

  10. Continued • For nonideal solutions: • Pj = P*j aj where aj = gj xj = activity of j at xj relative to RL • mjsoln= mjo(T) + mj*(T) + RT ln aj • Comparing equations: • aj = Preal/P* • aj/xi = gj = Preal/P*xi = Preal/Pideal

  11. Measure γ & Activity (a)

  12. Activities relative to (a) R L & (b) H L

  13. Excess Functions • DGIDmix = RT(n1ln x1 + n2ln x2) • For nonideal soln mixing: • DGNIDmix = RT(n1ln a1 + n2ln a2) • DGNIDmix = RT(n1ln x1 + n2ln x2 +n1ln g1 + n2ln g2) GE = DGNIDmix - DGIDmix = RT(+n1ln g1 + n2ln g2)

  14. Calculated gR for CS2/DMM Solns @ 35.2 ºC

  15. GE-x for CS2/DMM Solns

  16. Solution with Tuc< Tbp that shows Azeotrope

  17. Next Time Start Chapter 25: Solid-Liquid Solutions Solute?…Solvent?… Molarity?…Molality?… Colligative Properties

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