KMT and Gas Laws

1. KMT and Gas Laws States of Matter, Kinetic Molecular Theory, Diffusion, Properties of Gases, and Gas Laws

2. Standards 4. The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept: a. Students know the random motion of molecules and their collisions with a surface create the observable pressure on that surface. 4. b. Students know the random motion of molecules explains the diffusion of gases. 4. c. Students know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of ideal gases. 4. d. Students know the values and meanings of standard temperature and pressure (STP). 4. e. Students know how to convert between the Celsius and Kelvin temperature scales. 4. f. Students know there is no temperature lower than 0 Kelvin. 4. g.* Students know the kinetic theory of gases relates the absolute temperature of a gas to the average kinetic energy of its molecules or atoms. 4. h.* Students know how to solve problems by using the ideal gas law in the form PV = nRT. 4. i. * Students know how to apply Dalton’s law of partial pressures to describe the composition of gases and Graham’s law to predict diffusion of gases.

5. States of Matter Deionization Plasma Ionization Condensation Gas Boiling Liquid Sublimation Deposition Freezing Solid Melting

6. Condensation (Gas  Liquid)

7. Boiling(Liquid  Gas)

8. Sublimation (Solid  Gas)

9. Deposition (Gas  Solid)

10. Freezing (Liquid  Solid)

11. Melting (Solid Liquid)

12. Molecular Motion of Gases

13. Molecular Motion of Gases

14. KMT • KMT – Kinetic Molecular Theory • The path of any individual molecule could best be described as random.

15. Molecular Motion • The state of matter depends on how much energy(motion) the molecules, atoms, or ions have. • The state of matter also depends on how attracted the atoms, molecules, or ions are to each other.

16. Molecular Motion State of Matter Gas – Liquid + + H O O – + Na Solid Cl O H

17. Nonpolar molecules O O O O

18. Polar molecules – – – + + + + + + H H H O O O H H H

19. Ionic compounds – – – – – – + + + + + + Na Na Na Na Na Na Cl Cl Cl Cl Cl Cl

20. Molecular Twist and Stretch

21. Diffusion • Diffusion – when a substance spreads out in a gas or liquid. • Examples: • Perfume eventually reaching the far side of a room. • Kool-Aid dissolving into water.

22. Diffusion of Gases

23. Diffusion of Gases

24. Diffusion of Liquids

25. Temperature (T) • Kinetic energy is the energy of motion. • Temperature is defined as a measure of the average kinetic energy of the atoms or molecules.

26. Temperature (T) • There are two scales and an absolute unit. (degrees Fahrenheit, degrees Celsius, and Kelvin)

27. Temperature Scales Water Boils Human Body Water Freezes • 212°F • 98.7°F • 32°F • 100°C • 37°C • 0°C • 373K • 310K • 273K

28. Temperature Scales • 9,941°F • 70°F • -460°F • 5,505°C • 21°C • -273°C • 5,778K • 294K • 0K Surface of Sun Room Temp. Absolute Zero

29. Converting Temperatures • Fahrenheit Celsius °C = (°F – 32)×(5/9) • Celsius  Fahrenheit °F = °C ×(9/5) + 32 • Celsius Kelvin K = °C + 273.15

30. Absolute Zero • At Zero Kelvin (0 K or –273.15 °C), atoms and molecules stop moving. • There is no temperature lower than absolute zero (0 K).

31. Volume (V) • How much space is occupied by a fluid. • Liquid Gas • Usually gases are measured in Liters (L)

32. Pressure (P) • Defined as force divided by area. • The force comes from atoms’ or molecules’ collisions with the wall of the container. • The greater the number of collisions or the more energy with each collision, the greater the pressure.

33. Pressure (P) • Defined as force divided by area. • The force comes from atoms’ or molecules’ collisions with the wall of the container. • The greater the number of collisions or the more energy with each collision, the greater the pressure.

34. Pressure Units in.2

35. Pressure 0 atm Outer Space (a vacuum) 0.33 atm Top of Mt. Everest 1 atm Regular Atmosphere (at sea level) 1,072 atm At the Bottom of Mariana Trench

36. Gas Properties

37. STP = Standard Temperature and Pressure Temperature is 0°C = 273.15 K and Pressure is 1 atm = 101.3 kPa

38. Gas Laws • Most of the gas laws deal with taking a quantity of gas and changing one property (pressure, temperature, or volume) and predicting how the other properties will change in response.

39. Boyle’s Law When given a certain amount of gas, if you increase the pressure, the volume decreases. If you decrease the pressure, the volume increases. Mathematically: P1V1 = P2V2 P1V1 = P2 V2

40. Boyle’s Law When given a certain amount of gas, if you increase the pressure, the volume decreases. If you decrease the pressure, the volume increases. Mathematically: P1V1 = P2V2 P1V1 = P2 V2 This assumes a constant temperature (T)

41. Boyle’s Law Example Your nephew is playing with a balloon in the car as your family drives over a mountain pass. The balloon initially had a volume of 1 L when the car was at the bottom of the mountain (and the air pressure was 100 kPa). Now that your family is at the top the air pressure is 70 kPa. What is the new volume of the balloon? P1V1 = P2 V2

42. Boyle’s Law Example P1 = 100 kPa P2 = 70 kPa V1 = 1 L V2 = ? P1V1 = P2V2 (100 kPa)(1 L) = (70 kPa)•V2 100 kPa•L = 70 kPa•V2 70 kPa 70 kPa 1.43 L = V2

43. Boyle’s Law Example Low P Normal P

44. Boyle’s Law Example Normal P Low P V1 = 1 L V2 = 1.43 L

45. Charles’ Law When given a certain amount of gas, if you increase the temperature, the volume increases. If you decrease the temperature, the volume decreases. Mathematically: V1 V2 = You must use Kelvin temperatures! T1 T2 • V2 • T2 • V1 • T1 =

46. Charles’ Law When given a certain amount of gas, if you increase the temperature, the volume increases. If you decrease the temperature, the volume decreases. Mathematically: V1 V2 = You must use Kelvin temperatures! T1 T2 • V2 • T2 • V1 • T1 = This assumes a constant pressure (P)

47. Charles’ Law Example If 1.0 L of gas is contained within a piston at 27 ˚C (300 K), what will new volume be if the gas is cooled to -23 ˚C (250 K)? Assume that the pressure is constant. • V2 • T2 • V1 • T1 =

48. Charles’ Law Example V1= 1.0 LV2= ? T1= 300 KT2= 250 K • V2 • T2 • V1 • T1 • V2 • 250 K • V2 • 250 • 1.0 L • 300 K • 1.0 • 300 = = = • V2= 0.83 L (250) (250)

49. Charles’ Law This assumes a constant pressure (P)

50. Charles’ Law This assumes a constant pressure (P)