1 / 21

Chemistry 232

Chemistry 232. Multicomponent Phase Equilibria. P A *. liquid. vapour. Raoult’s Law . Variation in the total vapour pressure of a two component liquid mixture according to Raoult’s Law . P B *. X A. The Variation in Terms of Gas Phase Mole Fractions.

kayo
Download Presentation

Chemistry 232

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chemistry 232 Multicomponent Phase Equilibria

  2. PA* liquid vapour Raoult’s Law • Variation in the total vapour pressure of a two component liquid mixture according to Raoult’s Law PB* XA

  3. The Variation in Terms of Gas Phase Mole Fractions • yA the vapour phase mole fraction of A. PA* liquid vapour PB* yA

  4. A Liquid-vapour Phase Diagram • composition axis: liquid PA* vapour PB* ZA

  5. A Blow-up of the Two-phase Region

  6. Moving Down an Isopleth • isopleth - constant total composition • lever rule: nl = l’n’ 450 liquid a 350 b P (torr) c l’ n 300 n’ l d 250 vapour e 200 0.0 0.25 0.75 1.00 0.50 ZA

  7. Temperature-composition Phase Diagrams TA* TB* T / K xA yA ZA

  8. Simple Distillation of Liquid Mixtures • Vapour at composition a’2 is condensed, it becomes richer in the more volatile component. TB* a’2 T / K a2 boil condense a1 TA* a3 ZA

  9. Fractional Distillations • Repeat the evaporation and condensation cycle!

  10. Azeotropes • A low boiling azeotrope.

  11. Azeotropes • A High Boiling Azeotrope

  12. Liquid-Liquid Phase Diagrams • TUC - the upper critical temperature. Tuc T / K F`=2 F`=1 tie-line a’ l ’ l `` a`` XA

  13. Liquid-Liquid Phase Diagrams • TLC - the lower critical temperature. T / K F`=2 a’ l ’ l `` a`` F`=1 tie-line TLC XA

  14. Liquid-Liquid Phase Diagrams • A system exhibiting and upper and a lower critical solution temperature! TUC T / K TLC XA

  15. The distillation of partially miscible liquids • Complete miscibility occurs before boiling commences. vapour L + V T / K a’2 L + V a2 1 phase liquid 2 phase liquid a1 ZA

  16. The distillation of partially miscible liquids • Liquids remain immiscible even up to the boiling temperature. vapour L + V T / K L + V a b c 1 phase liquid 2 phase liquid ZA

  17. Liquid-Solid Phase Diagrams • Freezing points of solutions are dependent on the compositions of the solutions! • We have already examined briefly the freezing point depression of dilute soutions. • where fus,AH = enthalpy of fusion of A • TA and T*A are the freezing points of the solution and pure A, respectively.

  18. The Liquidus Curve for B in A • For a solution of B in liquid A. T*A T/K liquid solid liquidus curve XA

  19. The Liquidus Curve for A in B • For a solution of A in liquid B. T*B liquidus curve T/K liquid solid XA

  20. The S-L Phase Diagram • Overlapping the curves leads to the liquid-solid phase diagram for A and B. liquid T*A eutectic T*B solid A + solution solid B + solution solid A + solid B

  21. A Blow-up of the Two-phase Region • Tie lines connect the liquid phase of specified composition in equilibrium with either solid A or B. T*A liquid T*B tie line eutectic solid A + solution solid B + solution solid A + solid B

More Related