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4.6 Real solution: activity of solute and solvent

γ cs2. γ acetone. 4.6 Real solution: activity of solute and solvent. By R.L. The activity factor. Judged by Raoult’s law. Or by Henry’s Law. Pa. P. P B. P A. 1. 0. x A. Example: Acetic acid(A)/benzene(B) solution. By R.L:. By R.L. By H.L.

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4.6 Real solution: activity of solute and solvent

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  1. γcs2 γacetone 4.6 Real solution: activity of solute and solvent By R.L. The activity factor Judged by Raoult’s law Or by Henry’s Law

  2. Pa P PB PA 1 0 xA Example: Acetic acid(A)/benzene(B) solution By R.L: By R.L By H.L mixGm=RT(xA ln aA + xB ln aB)= – 1167J.mol-1

  3. According to H.L.: Example: Chloroform in actone, 298K According to R.L.: Calculate aA, γAfrom aB, γB---Gibbs-Duhem equation

  4. Osmotic coefficient: represent the activity of solvent molecule For example: 298K, KCl aqueous solution

  5. 4.7 Excess functions: represent the nonideality of the whole solution • The difference between the observed thermodynamic function of mixing and the function for an ideal solution excess For example: Excess entropy The significance: Related to molecular interaction A-A B-B A-B

  6. Excess Gibbs energy

  7. Excess enthalpy Gibbs-Helmholtz equation

  8. Tetrachloroethene/cyclopentane Excess volume

  9. or If Regular solutions The nonideality is totally coursed by HE ---the regular solutions

  10. Margules equations For different β Activity of regular solutions ΔmixG = nRT(xA ln xA + xB ln xB + βxAxB) GE= nβRTxAxB Benzene/Cyclohexane

  11. Understanding meaning of β Positive β Negative β Ideal solution Follow raoult’s Law For different β

  12. so and About regular solution Excess chemical potential

  13. ，so or Athermal solutions The nonideality of the solution coursed by excess entropy

  14. 4.8 Thermodynamic discussion about extraction distribution coefficient of B in two different solvent αand β

  15. Example • 291K, extraction of methylamine in chloroform by water V1, volume of chloroform solution V2, volume of water n, the times of extraction

  16. Review: About solution • Solute B+ solvent A= solution Gibbs-Duhem equation Gas(yA,yB) L(xA,xB) S(A) Duhem-Margules equation

  17. The chemical potential Ideal gas i = i y+ RT ln ( pi /py) Real gas i = i y+ RT ln ( fi /py) solution i(sln) = i(g)= iy(g)+ RT ln (pi / py) Nonideal solution： p2 = p2*a2 (R.L) = Kh,x a2 (H.L) = Kh,m a2 = Kh,c a2 pi = pi*(pure liquid) = pi*xi(ideal solution) = Kh,x xi(diluted solution) = Kh,mm = Kh,c c Diluted solution 2 (sln)= 2y(sln)+ RT ln(x2) x2, m/my,c/cy Real solution 2 (sln)= 2y(sln)+ RT ln(a2)

  18. Homework • Discussion: • Group I: Thermodynamics in Dialysis technique Group II: Osmosis phenomenon in biological systems Group III: If the solvent of an diluted solution follow Raoult’s Law, the solute would follow the Henry’s Law.

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