1. OB: Intro to phases chemistry The three states of matter Solids, liquids, and gases, and Changing from phase to phase. You must have a calculator and a reference table or you won’t learn.

2. 1. Matter comes in three phases, and we know that the matter can change from phase to phase. We’ll soon learn how and why this happens. 2. There are six phase changes that you need to know always: Melting/freezing boiling/condensing Sublimation/deposition 3. Energy is associated with the phases as well Gases have the highest energy, solids the lowest. 4. Water is our most common substance, and therefore we need to always be aware of the temperatures that the phase changes occur at (at normal pressures).

3. 373 K = 100 °C 273 K = 0 °C 0 K = absolute zero 5. Temperature chart for water at normal pressure.

4. 373 K = 100 °C 273 K = 0 °C 0 K = absolute zero 5. Temperature chart for water at normal pressure. Steam condenses, water vaporizes Ice melts, water freezes Gas phase Liquid phase SOLID phase

5. 6. Water is weird, because it’s common to us in all 3 phases. Most substances are not normally seen in all 3 phases in the normal temperatures that we live in. For example: Kelvin Temps WaterIronGoldCO 2 Boil temp gas phase starts 37330233080217 Freeze temp solid below this temp 27318081338195

6. 7. Although most of us wouldn’t realize this, boiling point is influenced by the air pressure as well. Just like most fish don’t know they’re wet, we don’t often realize the effect that the air has on us or everything else.

7. 8. Air pressure is measured with these unusual units… A. Atmospheres of pressure (atm). One atmosphere is the normal amount of air above us, so 1.0 atm is considered “normal” air pressure. B. Millimeters of Mercury (mm Hg) is next. I’ll show you tomorrow how the original barometers worked, how they measured air pressure. “Normal” was when the mercury rose up to a height of 760 mm. C. Kilo-pascals (kPa) is last, and most metric. We’ll use this one the most, and we’ll get used to the funky names. D. Pounds per Square Inch (psi) in America. It’s 14.7 psi for standard pressure. LOOK now at table A on the reference tables. Normal temperature is both 273 Kelvin or 0°C, and 10. Normal Pressure is 101.3 kPa, or 1.0 atm. (It’s also 760. mm Hg)

8. Time for a fun demo of air pressure (or two). First, notice I have nothing up my sleeves. I need one of those hats! 11. First, let me tell you that “normal” air pressure is sometimes still measured in pounds per square inch or psi. 12. Normal pressure is 14.7 psi. I just happen to have a hunk of steel that’s 1 square inch on the bottom and 14.7 pounds.

9. Next, let’s notice the force of the air pressure that we never even notice. Here’s a water glass, like the one in my hand. The top is about 2 inches across, and with that Area of a circle formula = πr 2 A = (3.14) x (1.25 inch) x (1.25 inch) = 4.91 in 2 My water is about a 0.75 pounds, so the pressure that this water would create if I turned it upside down would be slight (about ____________psi) WATCH! Think!

10. Air pressure pushes up (14.7 psi) Water pressure pushes down, about ______ psi Which is stronger?

11. 15. Air pressure conversions, using the “normal” air pressure equalities 101.3 kPa = 760. mm Hg = 1.0 atm = 14.7 psi Let’s convert higher than normal air pressure of 145 kPa into atmospheres.

12. Let’s convert higher than normal air pressure of 145 kPa into atmospheres. 145 kPa 1 X = 1.43 atm 1.0 atm 101.3 kPa 15. Air pressure conversions, using the “normal” air pressure equalities 101.3 kPa = 760. mm Hg = 1.0 atm = 14.7 psi

13. 16. The pressure in a balloon is 905 mm Hg. What’s that in kPa (kilopascals)?

14. 16. The pressure in a balloon is 905 mm Hg, what’s that in kilopascals? 905 mm Hg 1 X = 121 kPa 101.3 kPa 760. mm Hg

15. 17. As you climb up Mt. Everest (which is totally unsafe and also dangerous) the air pressure drops from normal to about 31.0 kPa. What is that in atmospheres?

16. 31.0 kPa 1 X 1 atm 101.3 kPa = = 0.306 atm 3 SF 17. As you climb up Mt. Everest (which is totally unsafe and also dangerous) the air pressure drops from normal to about 31.0 kPa. What is that in atmospheres?

17. 18. The air pressure in a scuba tank is in the range of 224 atm. Convert that into kilo-Pascals.

18. 224 atm 1 X 101.3 kPa 1 atm = = 22,691 kPa = 22,700 kPa 3 SF 18. The air pressure in a scuba tank is in the range of 224 atm. Convert that into kilo-Pascals.

19. Phase class #2 OB: Describing gases with the kinetic molecular theory of gases, detailing how barometers work, and then, lots of pressure unit conversion math You Your dog: Pressure Unit Conversion Math AKA: PUC

20. This theory explains how gases “work”. How they exist as gases, how they stay gases, how the particles of gas act (atoms or molecules), and how we understand gases in our minds. Depending how you count the concepts, there are seven points to ponder…

21. 19. The kinetic molecular theory of gases states that gases A. Are made up of small particles such as atoms or molecules B. And that these particles will act as if they are small, hard spheres. They aren’t really, they do have shapes, and are not spheres, but they act as if this is true.

22. 19. The kinetic molecular theory of gases states that gases A. Are made up of small particles such as atoms or molecules B. And that these particles will act as if they are small, hard spheres. They aren’t really, they do have shapes, and are not spheres, but they act as if this is true. C. They have no attraction for or any repulsion for any other gas particles. This is not true either, but the attraction and repulsion they have for one another is small, and unless crazy cold, no real effect on gases. D. The particles move very fast, and only in straight lines. It’s very geometric, no spiraling particles.

23. 19. The kinetic molecular theory of gases states that gases E. All collisions are elastic: when the gas particles hit each other all of their energy is transferred, none is lost. This is not true, but the loss of energy is small, and the addition of energy all the time from the Sun, and the Earth more than makes up for it. Gases do stay gases usually. F. Collisions result in pressures being exerted. The more collisions the higher the pressure. The stronger the collisions, the higher the gas pressure too.

24. 19. The kinetic molecular theory of gases states that gases G. Particles are separated by vast distances from each other relative to the size of the particles. Gases are mostly empty space, and particle size is insignificant. The particles do take up some space, but it’s tiny. In theory, the particles act as if they take up no space at all, but that’s silly.

25. 20. Gas pressure was originally measured in pounds per square inch because a bunch of smart guys, who came from Europe, where they used pounds for measuring, and who happened to invent the barometer, decided things.

26. So a bunch of these science guys go on a long round the world road trip, with a barometer (so they could say they were working!), and they measured how high up the mercury went near the oceans, up the mountains, in the hills, in cities, towns, caves, etc. They decided amongst themselves what “normal” was. The decision was that When the mercury rose up to 760. mm in height in the vacuum tube, the air pushing it that much was “normal” pressure. The rest is just math conversions, different instruments, and more math. Easy but we’ll practice some now. 21. Evangelista Torricelli, circa 1640, father of the Torricelli Tube, or the early mercury air barometer. (1 Torr is about 1 mm Hg)

27. 22. Today it’s a higher pressure day (cold air is denser than warm), so the pressure outside is about 825 mm Hg. Convert that to atmospheres and then to kilopascals.

28. 825 mm Hg 1 X = 1.09 atm 1.0 atm 760. mm Hg 825 mm Hg 1 X = 110. kPa 101.3 kPa 760. mm Hg 22. Today it’s a higher pressure day (cold air is denser than warm), so the pressure outside is about 825 mm Hg. Convert that to atmospheres and then to kilopascals.

29. 23. In Boulder, Colorado, where my mean sister in law Donna lives, the air pressure is notably lower than Vestal. That’s because she’s so high in the mountains, there is less air pressing on them than at lower altitudes like here. Air pressure in Boulder the other day was just 644 mm Hg. You’d be light headed probably. Convert that to atm and to kPa.

30. 644 mm Hg 1 X = 85.8 kPa 101.3 kPa 760. mm Hg 644 mm Hg 1 X = 0.847 atm 1.0 atm 760. mm Hg 23. In Boulder, Colorado, where my mean sister in law Donna lives, the air pressure is notably lower than Vestal. That’s because she’s so high in the mountains, there is less air pressing on them than at lower altitudes like here. Air pressure in Boulder the other day was just 644 mm Hg. You’d be light headed probably. Convert that to atm and to kPa.

31. 24. Convert 40.0 kPa into mm Hg and then into atm.

32. 40.0 kPa 1 X = 300. mm Hg 760 mm Hg 101.3 kPa 40.0 kPa 1 X = 0.395 atm 1.0 atm 101.3 kPa 24. Convert 40.0 kPa into mm Hg and then into atm.

33. 25. Last set today. Convert 2.55 atm into kilopascals and then into mm Hg

34. 2.55 atm 1 X = 258 kPa 101.3 kPa 1.0 atm 2.55 atm 1 X = 1938 kPa 760 mm Hg 1.0 atm 1940 kPa with 3SF 25. Last set today. Convert 2.55 atm into kilopascals and then into mm Hg

35. Phase Class #3 – Liquids get a calculator + reference table now Review temperature and pressure conversions, Table H and vapor pressure.

36. 26. Convert these 4 now… A. 120 ⁰ C into Kelvin B. 327 Kelvin to centigrade C. 0.556 atm to mm Hg D. 4.57 atm to kPa

37. 26. Convert 120 ⁰ C into Kelvin 327 Kelvin to centigrade 0.556 atm to mm Hg 4.57 atm to kPa K = C + 273 K = 120 + 273 = 393 Kelvin K = C + 273 327 K = C + 273 327 K = 54 ⁰ C 0.556 atm 1 X = 423 mm Hg 760 mm Hg 1.0 atm 4.57 atm 1 X = 463 kPa 101.3 kPa 1.0 atm

38. 27. Liquids are substances with particles sliding on each other, attached loosely by inter particle attractions. The particles do not have enough kinetic energy (motion) to shake apart into a gas, nor so little energy that they would lock together into a solid.

39. 28. When liquids get enough energy they reach the boiling point. At the boiling point ALL molecules of a liquid have enough energy to go into the gas phase. This is called vaporization. 29. Vaporization is evaporation too, which is when few particles of a liquid get enough energy by bouncing around to escape to the gas phase. 30. Evaporation happens to every liquid at every temperature. 32. The hotter liquids are, the more evaporation can occur since more particles get enough energy to leap to a gas. See the water evaporating from the lake? On every day, no matter what the temperature, all day long, at least some water evaporates.

40. LIQUID GAS Phase change from liquid to gas… 33. Evaporation is when some water molecules (any liquid) escape because individually they get enough kinetic energy to jump into the air. Boiling is when the entire liquid has enough kinetic energy to change phase. 34. When kinetic energy exceeds the forces of attraction, liquids become gases. This is an OPEN SYSTEM, the beaker will eventually empty. 35. If this liquid is boiling it’s quicker, if it’s cool, then the vaporization process is slower.

41. Donna lives high up in the Rockies, in Boulder Colorado. She does like to cook potions, but things with her are not like they are with you here. For example, she never shops at a mall. In Vestal we have a normal air pressure, our altitude is about 1000 feet above sea level. In Boulder, they’re nearly 5,400 feet above sea level, so their air pressure is markedly lower. If the pressure is normal here, it’s about 85% lower there. Vestal 1.0 atm Boulder 0.85 atm. What temperature will that water boil in Boulder? 36. How do we figure this out?

42. Vestal 101.3 kPa 70°C Vestal 101.3 kPa 100°C Boulder 85.0 kPa ~97°C Water does not boil. It can’t over come the attraction and downward air pressure Evaporation happens Water does boil. It can overcome the attraction and downward air pressure Evaporation happens Water boils at a lower temperature! There is lower air pressure holding it down in the pot! Air Pressure water Air Pressure water Air Pressure water 37.

43. 38. Liquids (even water) boil when all the particles have enough energy to overcome the internal attraction that they have for themselves, and enough energy to overcome the air pressure pushing down upon the surface. 39. Boiling point is not JUST temperature driven, it’s controlled by the temperature and the pressure together. 40. High pressures will increase the energy (temperature) required to boil any liquid. Lower pressures will decrease the energy needed to boil a liquid. 41. The internal attraction of the particles is a constant for each particular liquid. This internal attraction is measured by VAPOR PRESSURE.

44. WATER Corked top Evaporation (up arrows) Condensation (down arrows) 42. In a closed system, at a steady temperature a dynamic equilibrium is reached. This is when the evaporation rate equals the condensation rate. This is only possible in a closed system.

45. WATER Corked top Evaporation (up arrows) Condensation (down arrows) In a closed system, at a steady temperature a dynamic equilibrium is reached. This is when the evaporation rate equals the condensation rate. This is only possible in a closed system. 43. If the system is heated, more evaporation occurs, until a new dynamic equilibrium is reached. If it’s cooled, less evaporation will occur, until a new dynamic equilibrium is reached.

46. WATER Corked top Evaporation (up arrows) Condensation (down arrows) 44. This space above the water contains air, and has air pressure that matches the air pressure outside the glass. The evaporation causes more particles of gas to move into that space, increasing the pressure. This extra pressure is called VAPOR PRESSURE.

47. Pressure kPa 101.3 kPa temperature, Centigrade degrees 0 50 100 45. The vapor pressure of water (part of table H)

48. Pressure kPa 101.3 kPa temperature, Centigrade degrees 0 50 100 The vapor pressure of water (part of table H) 46. Big black dot indicates the “normal boiling point”, which is the BP at normal pressure. 47. The curved line indicates ALL of the boiling points of water, at all different pressures.

49. Pressure kPa 101.3 kPa temperature, Centigrade degrees 0 50 100 The vapor pressure of water (part of table H) 48. H 2 O at these pressures and temperatures is a LIQUID 49. H 2 O at these pressures and temperatures is a GAS

50. 50. Table H is the vapor pressure of 4 different compounds, water included. Only look at one curve, or one liquid, at any time. Behind the curve is liquid, in front of the curve it’s a gas.

51. Phase Class #4 Understanding Table H and Vapor Pressure Take out your reference tables now

52. WATER Corked top Evaporation (up arrows) Condensation (down arrows) 51. In a closed system, at a steady temperature a dynamic equilibrium is reached. This is when the evaporation rate equals the condensation rate. This is only possible in a closed system. Air pressure outside bottle is about 101.3 Pa, same inside to start.

53. WATER Corked top Evaporation (up arrows) Condensation (down arrows) 52. If the close system is heated, more evaporation occurs, until a new dynamic equilibrium is reached. If it’s cooled, less evaporation will occur, until a new dynamic equilibrium is reached. Air pressure outside still about 101.3 kPa, inside the pressure is increasing.

54. WATER Corked top Evaporation (up arrows) Condensation (down arrows) 53. The extra pressure inside that bottle is called the vapor pressure. It’s added to the existing air pressure present from the start. Air pressure outside still about 101.3 kPa, inside the pressure is increasing.

55. 54. Table H is the vapor pressure of 4 different compounds, water included. Only look at one curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas.

56. Table H is the vapor pressure of 4 different compounds, water included. Only look at one curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas. Let’s Just Do This Slide, no notes… 12 3 4 Let’s talk ONLY about water… At each point, what phase is the water in? 1. 2. 3. 4.

57. Table H is the vapor pressure of 4 different compounds, water included. Only look at one curve, or one liquid, at any time. Behind the curve is liquid. In front is a gas. 12 3 4 Let’s talk ONLY about water… At each point, what phase is the water in? 1. liquid 2. liquid 3. liquid 4. gas

58. 55. At each point, what is the vapor pressure of water? 101.3 kPa + 40⁰C 75 kPa + 95⁰C 150 kPa + 110⁰C 20 kPa + 65⁰C

59. 55. At each point, what is the vapor pressure of water? 101.3 kPa + 40⁰C LIQUID 75 kPa + 95⁰C GAS 150 kPa + 110⁰C LIQUID 20 kPa + 65⁰C GAS

60. AB C JUST DO THESE TOO At these points A, B, and C What phase is water? What phase is ethanoic acid? What phase is ethanol? What phase is propanone?

61. AB C At points A, B, and C What phase is water? A liquid B gas C liquid

62. AB C At points A, B, and C What phase is ethanoic acid? A liquid B liquid C liquid

63. AB C At points A, B, and C What phase is ethanol? A liquid B gas C gas

64. AB C At points A, B, and C What phase is propanone? A gas B gas C gas

65. 56. How much extra pressure is added to a sealed flask containing water at 50 ⁰ C? 56A. (what’s the vapor pressure of water at 50 ⁰ C?)

66. Phase Class #5 OB: Practice phase concepts: cooling and heating curves, phase diagrams, pressure conversions, table H problems. Take out reference tables.

67. 57. Draw the Cooling curve for cobalt. 58. On the same graph, draw the heating curve for cadmium. Titles, axis labels and scales, be big. Write BP + FP for both. Temp Kelvin Energy added (or removed) at constant rate over time 3200 2400 1600 800

68. Draw the heating curve for cobalt. On the same graph, draw the cooling curve for cadmium. Titles, axis labels and scales, be big. Temp Kelvin Energy added (or removed) at constant rate over time 3200 2400 1600 800 Cobalt BP: 3200 K FP: 1768 K Cadmium BP: 1040 K FP: 594 K

69. 59. Why are the flat lines different lengths on every heating curve (and every cooling curve)? 60. BC represents the melting of ice. It takes for water, 334 Joules of energy to melt one gram of ice from solid to liquid without increasing the temperature. It’s called the heat of fusion For water: H F = 334 J/gram 61. DE represents the boiling of water into steam. It takes for water, 2260 Joules of energy to vaporize one gram of water to steam without increasing the temperature. It’s called the heat of vaporization For water: H V = 2260 J/gram 62. The phase change from liquid to gas is MUCH more energetic than melting solid to liquid. For water, it’s ~ 7X more!

70. 63. A phase diagram shows a substance’s range of phases through temperature + pressures. Here is the phase diagram for water. 64. Special Points on this graph: T m : normal melting point T b : normal boiling point TP: triple point CP: critical point

71. Imagine you have two beakers of liquid, one has 500. mL ethanol alcohol and the other has 500. mL of propanone. They are sitting on the desk in front of you. Put a cork into each top. AIR PRESSURE 101.3 kPa Start pressure inside flasks the same Warm up the room to 25⁰C 65. What is pressure inside each flask?

72. Imagine you have two beakers of liquid, one has 500. mL ethanol alcohol and the other has 500. mL of propanone. They are sitting on the desk in front of you. Put a cork into each top. AIR PRESSURE 101.3 kPa Start pressure inside flasks the same 25⁰C Vapor Pressure ethanol @ 25⁰C is about 8 kPa Vapor pressure propanone @ 25⁰C is about 31 kPa 66. What if we heat it up to 65⁰C next???

73. Imagine you have two beakers of liquid, one has 500. mL ethanol alcohol and the other has 500. mL of propanone. They are sitting on the desk in front of you. Put a cork into each top. AIR PRESSURE 101.3 kPa Start pressure inside flasks the same 65⁰C Vapor Pressure ethanol @ 65⁰C is about 60 kPa Vapor pressure propanone @ 65⁰C is about 135 kPa KABOOM!

74. 67. Properties of SOLIDS, LIQUIDS, and GASES Compared SOLIDS Particles are strongly attracted to each other, other than some vibration there is nearly no movement of the atoms or molecules, they have a rigid or lattice arrangement of the particles, they keep their shapes and volumes, they do not take the shape of their containers. Solids cannot be compressed very much because the particles are very close together. Because of this most solids have a high density compared to their liquids or gases. When energy or heat is added, the particles will vibrate more, which often makes solids expand when heated. Particles in solids have the lowest kinetic energy. Give solids enough energy (at the proper pressure) and they will vibrate so much that they break apart and turn into....

75. LIQUIDS Particles have some attraction to each other but not enough to make them stuck. Liquids flow over themselves, the particles are in constant random motion. Liquids do not have a definite shape which means they take the shape of the container you put them in. If you spill liquids, the force of gravity spreads them out quite well. The hotter liquids get when you add energy, the faster the particles move, and liquids too expand slightly when heated. Liquids are dense as well, but usually not as dense as solids are. Heat a liquid enough, the particles move so much that they turn into...

76. GASES There is virtually no attractive or repulsive force between the particles. The particles move in straight lines and very fast. They collide with other particles all of the time. These collisions will cause gas (or air) pressure. Gases take the shape of the container that you put them in. Any amount of a gas will fill any container that you put it in. The collisions are considered to be elastic, meaning there is no loss of kinetic energy due to the collisions. Heated gases make the particles move faster and have more collisions, causing expansion if possible, or greater pressures if contained in a definite volume. Gas Particles have the highest kinetic energy. Gases have very low density.

77. Gas Pressure is measured with different pressure units, all on table A. Let’s add mm Hg now to the reference tables now. 1.0 atm = 760. mm Hg = 101.3 kPa = 14.7 psi 68. Today’s pressure is exactly 1.14 atm. Convert that to mm Hg, and kPa right now…

78. This slide left intentionally blank, you know why…

79. 1.14 atm 1 X = 866 mm Hg (3 SF) 760. Mm Hg 1.0 atm 1.14 atm 1 101.3 kPa 1.0 atm X = 115 kPa (3 SF) 68.

80. 69. At any temperature, say 65 °C, ethanonic acid has the lowest vapor pressure, propanone the highest. WHY??? Each liquid, these 4 included, at any one temperature will evaporate to a certain degree. How much this happens is connected first to the temperature, and then, to how strong the inter- molecular attractions the molecules have for each other. At 65 °C Propanone has the lowest intermolecular attraction and therefore the highest vapor pressure. Ethanoic acid has strong intermolecular attraction, so low vapor pressure.

81. 70. Put 2 notes onto your reference tables now. Ethanoic acid has the lowest vapor pressure of these four liquids, at any temperature because it has the strongest intermolecular attractions for itself. Propanone has the highest vapor pressure of these four liquids, at any temperature, because it has the weakest intermolecular attractions for itself.

82. Heating curve for an unknown substance BP FP K Energy being added at a constant rate over time. 71. Label points A to F left to right Show what happens to Temperature from points BC and DE Then explain Potential Energy from BC and DE (use next slide to draw)

83. Heating curve for an unknown substance BP in FP K Energy being added at a constant rate over time.

84. Heating curve for an unknown substance BP in FP K B C D A BC there is no change in temperature. DE there is no change in temperature. Ergo: Kinetic Energy is steady. Potential Energy must increase there. Energy being added at a constant rate over time. PE F E

85. Heating curve for an unknown substance BP in FP K B C D E From CD there is an increase in temperature. That means Kinetic Energy Increases too 72. If kinetic energy is changing, What does the potential energy do from C to D? Energy being added at a constant rate over time. Temp KE

86. Heating curve for an unknown substance BP in FP K B C D E From CD there is an increase in temperature. That means Kinetic Energy Increases too If kinetic energy is changing, Potential Energy is steady Energy being added at a constant rate over time. Temp KE

87. 73. Kinetic Energy & Temperature are the same thing, sort of. The greater the KE, the greater the temp. Lower temp = Lower KE 74. Temp + Kinetic energy are like Michael Jackson’s hand & his glove. What ever one does, so does the other. 75. The other energy, Potential Energy, is used when there is no change in the kinetic energy. It’s for those phase change times. 76. If kinetic energy (temp) is changing, potential energy is steady. 77. In a phase change kinetic energy is steady (so is temp), then the PE is going up in a heating curve, or the PE is going down in a cooling curve.