Kinetic Theory of Matter (KTM)

1. Kinetic Theory of Matter (KTM) AKA: Kinetic Molecular Theory (KMT) Molecular Kinetic Theory (MKT) Not associated with TKM—the international postal code for Turkmenistan

2. Rule 1 • All matter is composed of particles in constant motion

3. Rule 2 • Temperature is a measure of the kinetic energy of the particles.

4. Rule 2 (a and b) • Temperature is a measure of the kinetic energy of the particles. a) When you heat a sample, the particles speed up b) When you cool a sample the particles slow down

5. After that, things get hazy. ?

6. Consider the state: • Solid Liquid Gas

7. Particles in motion: • Solid Liquid Gas

8. Particles in motion: • Solid Liquid Gas Vibrating about a fixed position

9. Particles in motion: • Solid Liquid Gas Moving over and around other particles, unlikely to escape surface

10. Particles in motion: • Solid Liquid Gas Moving freely, colliding with other particles and the walls of container

11. Consider state changes: Gas Sublimation Solid Melting Condensation Freezing Boiling, evaporation, vaporization Liquid

12. Particles on particles: • Solid Liquid Gas Particles in contact Particles in contact Particles not touching

13. This is huge. Really.

14. Values and preferred units • P—atmospheres • T—kelvins • V—Liters • n—moles

15. Conversions • P: 1 atm =760 mmHg=760torr =101.3 kPa=101,325 Pa • T: T(k) = T(oC) + 273 • V: 1L=1000 ml=.001 m3

16. How fast do particles move? It depends on:

17. How fast do particles move? It depends on: • Temperature: • Size of the particle:

18. How fast do particles move? It depends on: • Temperature: High T  faster motion • Size of the particle: Smaller  faster

19. Cool, medium, warm

20. Phase diagrams What about water? P 1 atm 0 atm T 0 k 273 k 373 k

21. Phase diagrams What about water? Water melts / freezes Water boils/ condenses P 1 atm 0 atm T 0 k 273 k 373 k

22. Phase diagrams What about water? P Water is a solid Water is a liquid Water is a gas 1 atm 0 atm T 0 k 273 k 373 k

23. Phase diagrams What about water? Increasing pressure will melt ice Decreasing pressure will boil water P Water is a liquid Water is a solid Water is a gas 1 atm 0 atm T 0 k 273 k 373 k

24. Phase diagrams What about water? P Water is a liquid Water is a solid Water is a gas 1 atm Sublimation occurs at low T and P 0 atm T 0 k 273 k 373 k

25. Phase diagrams What about water? P Water is a liquid Water is a solid Water is a gas 1 atm 0 atm T 0 k 273 k 373 k

26. Phase diagrams Describe these processes Water is a liquid A B H P Water is a solid C I G 1 atm E Water is a gas D F 0 atm T 0 k 273 k 373 k

27. Phase diagrams Describe these processes P Heating curve lab 1 atm Vacuum pump demo 0 atm T 0 k 273 k 373 k

28. Phase diagrams Water P Normal melting point 1 atm Normal boiling point Triple point 0 atm T 0 k 273 k 373 k

29. Phase diagrams Water P 1 atm Critical pressure 0 atm T 0 k 273 k 373 k

30. Phase diagrams Most other substances P Critical pressure Critical temperature 0 atm T 0 k

31. The phase diagram for water

32. Phase diagrams 1 atm P 0 atm T 0 k

33. Phase diagrams 1 atm P Critical pressure Critical temperature 0 atm T 0 k

34. The phase diagram for CO2

35. The phase diagram for water

36. Can you explain why each of these phenomena occurs? Thermal expansion of a solid—solids expand when heated Thermal expansion of a liquid –liquids expand when heated Thermal expansion of a gas –gasses expand when heated

37. Can you explain why each of these phenomena occurs? Compressibility of gasses—gasses can be compressed into a smaller volume Incompressibility of liquids –liquids can’t be compressed into a smaller volume Incompressibility of solids –solids can’t be compressed into a smaller volume

38. Can you explain why each of these phenomena occurs? Conduction of heat between two objects in contact—the cool one warms up. Heat flow stops when temperatures are equal

39. Can you explain why each of these phenomena occurs? Fluidity of gasses—gasses flow, they have no fixed shape Fluidity of liquids—liquids flow, they have no fixed shape Rigidity of solids—solids do not flow, they have a fixed shape

40. Can you explain why each of these phenomena occurs? Melting point of a solid —at a certain temperature, a solid changes into a liquid Boiling point of a liquid —at a certain temperature, a liquid changes into a gas Freezing point of liquids –at a certain temperature, a liquid changes into a solid Melting is endothermic (requires heat) Boiling is endothermic (requires heat)

41. Can you explain why each of these phenomena occurs? Liquification of gasses is accomplished at low temperatures and high pressures Sublimation of solids (to gas) at low pressures Sublimation of solids (to gas) at high temperatures Evaporation cools a liquid You can see your breath on a cold day

42. Can you explain why each of these phenomena occurs? Boyle’s Law —when the volume of a gas is reduced, its pressure increases Charles’ Law —when gasses are cooled, their volumes act as if they will reach zero volume at a temperature of absolute zero Avogadro’s Law —identical volumes of gasses contain the same number of particles Graham’s law —heavier gasses diffuse slower Dalton’s law of partial pressures —the total pressure of a mixture of gasses is the sum of the pressures of each gas.

43. Can you explain why each of these phenomena occurs? Decrease in boiling point of a liquid with lower pressure Increase in boiling point when solutes are added to a solvent Decrease in freezing point when solutes are added to a solvent Metals conduct heat better than other solids