2. Ethylene glycol, HOCH 2 CH 2 OH, boils at 198 o C and melts at -13 o C. What happens to the melting point of water if you add antifreeze? Melting point goes down. Boiling Points - Distillations

3. What happens to the boiling point of water if you add antifreeze? The boiling point goes up. Add Antifreeze

4. Solids Usually melt low Liquids Usually boil between the two components Mixtures

5. Solution boils when the vapor pressure = applied pressure Vapor pressure of water vs. temperature

6. If you add salt, NaCl, to water what happens to the melting point? Impurities depress the melting point so it goes down. Add Salt

7. If you add salt, NaCl, to water what happens to the boiling point? The boiling point goes up. Salt Boiling Point

8. P = P o *N Observed Pressure Pure Substance Mole Fraction Raoult’s Law

9. Two Volatile Liquids

10. a P a = P o a * N a b P b = P o b * N b Mixture boils when P a + P b = P applied Two Volatile Liquids

11. Plot of boiling point vs. mole fraction for a mixture of acetone and benzene. Boiling point vs. mole fraction

12. Boiling point of an acetone-benzene mixture with a mole fraction benzene of 0.50 What is the composition of the vapor? Boiling point vs. mole fraction

13. Vapor richer in the lower boiling component

14. Fractional Distillation

16. HETP = 1.5 cm Packed Column

17. HETP = 10 cm Vigreux Column

18. Which column has the greater holdup? Packed because it has the larger surface area.

19. Separations Which column would you use to separate a mixture of pentane, b.p. 36 o and octane, b.p. 99 o ? Vigreux

20. Separations Which column would you use to separate a mixture of methyl alcohol, b.p. 65 o and water, b.p. 100 o ? Packed

21. Separate mixture of methanol and water. Plot volume distilled vs. temperature. Experiment

22. Setup

23. CH 3 OH Methyl alcohol is toxic!

24. 14/20 20 mm 14 mm Standard Taper Joints

25. Grease joints to prevent sticking.

26. Thermowell

27. Plug the thermowell into the variable transformer

28. Boiling Chips Put boiling chips in bottom of flask

29. Distilling Column

30. Thermometer Adapter

31. Digital Thermometer

32. Probe for digital thermometer

33. Digital Thermometer

34. Water in Water out

35. Clamps

36. Same interactions between like and unlike molecules NONIDEAL MIXTURES: Strong attractions between like molecules Strong attractions between unlike molecules A. B. IDEAL MIXTURES:

37. Minimum - boiling azeotrope Ethanol - Benzene

38. Min Azeotrope

39. Maximum-boiling azeotrope Acetone - Chloroform

40. Max Azeotrope

41. Simple Distillation