1. What do you know about GASES? Make a list of 5 things you know about gases: 1 - 5

2. 2 Unit 6.1 - Gases 6.1.1 Properties of Gases 6.1.2 Gas Pressure

3. 3 Kinetic Theory of Gases A gas consists of small particles that move rapidly in straight lines have essentially no attractive (or repulsive) forces are very far apart have very small volumes compared to the volumes of the containers they occupy have kinetic energies that increase with an increase in temperature

4. 4 Properties of Gases Gases are described in terms of four properties: pressure (P), volume (V), temperature (T), and amount (n).

5. 5 Gas pressure is the force acting on a specific area Pressure (P) = force area has units of atm, mmHg, torr, lb/in. 2 and kilopascals(kPa). 1 atm = 760 mmHg (exact) 1 atm = 760 torr 1 atm = 14.7 lb/in. 2 1 atm = 101.325 kPa Gas Pressure

6. 6 Atmospheric Pressure Atmospheric pressure is the pressure exerted by a column of air from the top of the atmosphere to the surface of the Earth

7. 7 Atmospheric Pressure (continued) Atmospheric pressure is about 1 atmosphere at sea level depends on the altitude and the weather is lower at high altitudes where the density of air is less is higher on a rainy day than on a sunny day

8. Unit 6.1 - Gases 6.1.3 Pressure and Volume (Boyle’s Law) 8

9. Boyle’s Law Boyle’s law states that the pressure of a gas is inversely related to its volume when T and n are constant if the pressure (P) increases, then the volume (V) decreases 9

10. 10 In Boyle’s law The product P x V is constant as long as T and n do not change. P 1 V 1 = 8.0 atm x 2.0 L = 16 atm L P 2 V 2 = 4.0 atm x 4.0 L = 16 atm L P 3 V 3 = 2.0 atm x 8.0 L = 16 atm L Boyle’s law can be stated as P 1 V 1 = P 2 V 2 (T, n constant) PV Constant in Boyle’s Law

11. 11 Solving for a Gas Law Factor The equation for Boyle’s law can be rearranged to solve for any factor. P 1 V 1 = P 2 V 2 Boyle’s Law To solve for V 2, divide both sides by P 2. P 1 V 1 = P 2 V 2 P 2 P 2 V 1 xP 1 = V 2 P 2

12. 12 Boyle’s Law and Breathing: Inhalation During inhalation, the lungs expand the pressure in the lungs decreases air flows towards the lower pressure in the lungs

13. 13 Boyle’s Law and Breathing: Exhalation During exhalation, lung volume decreases pressure within the lungs increases air flows from the higher pressure in the lungs to the outside

14. 14 Guide to Calculations with Gas Laws

15. Unit Abbreviations for Gas Law Problems Abbreviations: atm - atmosphere mmHg - millimeters of mercury torr - another name for mmHg Pa - Pascal (kPa = kilo Pascal) K - Kelvin °C - degrees Celsius

16. Conversion Values for Gas Law Problems Conversions: K = °C + 273 1 cm3 (cubic centimeter) = 1 mL (milliliter) 1 dm3 (cubic decimeter) = 1 L (liter) = 1000 mL Standard Conditions: (same as on slide #4) 0.00 °C = 273 K 1.00 atm = 760.0 mmHg = 101.325 kPa = 101,325 Pa

17. 17 Freon-12, CCl 2 F 2, is used in refrigeration systems. What is the new volume (L) of an 8.0 L sample of Freon gas after its pressure is changed from 550 mmHg to 2200 mmHg at constant T? STEP 1 Set up a data table: Conditions 1Conditions 2 Know Predict P 1 = 550 mmHgP 2 = 2200 mmHg P increases V 1 = 8.0 LV 2 = ? V decreases Calculation with Boyle’s Law

18. 18 STEP 2 Solve Boyle’s law for V 2. When pressure increases, volume decreases. P 1 V 1 = P 2 V 2 V 2 = V 1 x P 1 P 2 STEP 3 Set up problem V 2 = 8.0 L x 550 mmHg = 2.0 L 2200 mmHg pressure ratio decreases volume Calculation with Boyle’s Law (continued)

19. Problems with Boyle’s Law 1. A gas occupies 12.3 liters at a pressure of 40.0 mmHg. What is the volume when the pressure is increased to 60.0 mmHg? 2. If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm? 3. A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm? 4. A gas occupies 11.2 liters at 0.860 atm. What is the pressure if the volume becomes 15.0 L? 5. 500.0 mL of a gas is collected at 745.0 mmHg. What will the volume be at standard pressure?

20. Check your work 1) 8.2 L 2) 1.44L 3) 0.520 L 4) 0.642 atm 5) 490 mL

21. 21 Unit 6.1 - Gases 6.1.4 Temperature and Volume (Charles’s Law)

22. 22 Charles’s Law In Charles’s law, the Kelvin temperature of a gas is directly related to the volume P and n are constant when the temperature of a gas increases, its volume increases

23. STP represents Standard Temperature & Pressure STP conditions are: 0 0 C for temperature and 1 atm for pressure (but note that most of the time you will need to convert these to K or kPa values, that would be 273K and 101.3 kPa)

24. 24 For two conditions, Charles’s law is written V 1 = V 2 (P and n constant) T 1 T 2 Rearranging Charles’s law to solve for V 2 gives T 2 x V 1 = V 2 x T 2 T 1 T 2 V 2 = V 1 x T 2 T 1 Charles’s Law: V and T

25. 25 A balloon has a volume of 785 mL at 21 °C. If the temperature drops to 0 °C, what is the new volume of the balloon (P constant)? STEP 1 Set up data table: Conditions 1 Conditions 2 Know Predict V 1 = 785 mL V 2 = ? V decreases T 1 = 21 °C T 2 = 0 °C = 294 K = 273 K T decreases Be sure to use the Kelvin (K) temperature in gas calculations. Calculations Using Charles’s Law

26. 26 Calculations Using Charles’s Law (continued) STEP 2 Solve Charles’s law for V 2 : V 1 = V 2 T 1 T 2 V 2 = V 1 x T 2 T 1 Temperature factor decreases T STEP 3 Set up calculation with data: V 2 = 785 mL x 273 K = 729 mL 294 K

27. 27 Unit 6.1 - Gases 6.1.5 Temperature and Pressure (Gay-Lussac’s Law)

28. 28 Gay-Lussac’s Law: P and T In Gay-Lussac’s law, the pressure exerted by a gas is directly related to the Kelvin temperature V and n are constant P 1 = P 2 T 1 T 2

29. 29 A gas has a pressure at 2.0 atm at 18 °C. What is the new pressure when the temperature is 62 °C? (V and n constant) STEP 1 Set up a data table: Conditions 1 Conditions 2 Know Predict P 1 = 2.0 atm P 2 = ? P increases T 1 = 18 °C + 273 T 2 = 62 °C + 273 T increases = 291 K = 335 K Calculation with Gay-Lussac’s Law

30. 30 Calculation with Gay-Lussac’s Law (continued) STEP 2 Solve Gay-Lussac’s Law for P 2 : P 1 = P 2 T 1 T 2 P 2 = P 1 x T 2 T 1 STEP 3 Substitute values to solve for unknown: P 2 = 2.0 atm x 335 K = 2.3 atm 291 K Temperature ratio increases pressure

31. Problems using Charles’s Law 1. Calculate the decrease in temperature when 2.00 L at 20.0 °C is compressed to 1.00 L. 2. 600.0 mL of air is at 20.0 °C. What is the volume at 60.0 °C? 3. A gas occupies 900.0 mL at a temperature of 27.0 °C. What is the volume at 132.0 °C? 4. What change in volume results if 60.0 mL of gas is cooled from 33.0 °C to 5.00 °C?

32. Check your work 1)147 K is new temperature 2)682 mL 3)1220 mL or 1.22 X 10 3 4)54.5 mL

33. Problems using & Gay-Lussac’s Law 5. Determine the pressure change when a constant volume of gas at 1.00 atm is heated from 20.0 °C to 30.0 °C. 6. A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at standard temperature? 7. A gas has a pressure of 699.0 mmHg at 40.0 °C. What is the temperature at standard pressure? 8. If a gas is cooled from 323.0 K to 273.15 K and the volume is kept constant what final pressure would result if the original pressure was 750.0 mmHg?

34. Check your work 1)1.03 atm 2)0.313 atm 3)340 K 4)634.2 mm Hg

35. 35 Start here: Unit 6.1 - Gases 6.1.6 The Combined Gas Law (use this & leave off any variable that is a constant or not even talked about in the problem, it is understood to be a constant.)

36. Summary of Gas Laws The gas laws can be summarized as follows: 36

37. 37 The combined gas law uses Boyle’s Law, Charles’s Law, and Gay-Lussac’s Law (n is constant). P 1 V 1 = P 2 V 2 T 1 T 2 Combined Gas Law

38. 38 A sample of helium gas has a volume of 0.180 L, a pressure of 0.800 atm and a temperature of 29 °C. At what temperature (°C) will the helium have a volume of 90.0 mL and a pressure of 3.20 atm (n constant)? Combined Gas Law Calculation

39. 39 STEP 2 Solve for T 2 P 1 V 1 =P 2 V 2 T 1 T 2 T 2 = T 1 x P 2 x V 2 P 1 V 1 STEP 3 Substitute values to solve for unknown. T 2 = 302 K x 3.20 atm x 90.0 mL = 604 K 0.800 atm 180. mL T 2 = 604 K  273 = 331 °C Combined Gas Law Calculation (continued)

40. Combined Gas Law Problems 1. A gas has a volume of 800.0 mL at –23.00 °C and 300.0 torr. What would the volume of the gas be at 227.0 °C and 600.0 torr of pressure? 2. 500.0 liters of a gas are prepared at 700.0 mmHg and 200.0 °C. The gas is placed into a tank under high pressure. When the tank cools to 20.0 °C, the pressure of the gas is 30.0 atm. What is the volume of the gas?

41. 3. What is the final volume of a 400.0 mL gas sample that is subjected to a temperature change from 22.0 °C to 30.0 °C and a pressure change from 760.0 mmHg to 360.0 mmHg? Check your work 1) 800 mL 2) 9.51 L

42. 42 Unit 6.1 - Gases 6.1.7 Volume and Moles (Avogadro’s Law)

43. 43 Avogadro's Law: Volume and Moles Avogadro’s law states that the volume of a gas is directly related to the number of moles (n) of gas T and P are constant V 1 = V 2 n 1 n 2

44. 44 The volumes of gases can be compared at STP (Standard Temperature and Pressure) when they have the same temperature Standard temperature (T) = 0 °C or 273 K the same pressure Standard pressure (P) = 1 atm (760 mmHg) STP

45. 45 Molar Volume The molar volume of a gas is measured at STP (standard temperature and pressure) is 22.4 L for 1 mole of any gas

46. 46 Molar Volume as a Conversion Factor The molar volume at STP has about the same volume as 3 basketballs can be used to form 2 conversion factors: 22.4 L and 1 mole 1 mole 22.4 L

47. 47 Guide to Using Molar Volume

48. 48 Using Molar Volume What is the volume occupied by 2.75 moles of N 2 gas at STP? STEP 1 Given: 2.75 moles of N 2 Need: Liters of N 2 STEP 2 Write a plan: Use the molar volume to convert moles to liters.

49. 49 Using Molar Volume (continued) STEP 3 Write equalities and conversion factors: 1 mole of gas = 22.4 L 1 mole gas and 22.4 L 22.4 L 1 mole gas STEP 4 Substitute data and solve: 2.75 moles N 2 x 22.4 L = 61.6 L of N 2 1 mole N 2

50. 50 Unit 6.1 - Gases 6.1.8 The Ideal Gas Law

51. 51 The relationship between the four properties (P, V, n, and T) of gases can be written equal to a constant R. PV = R nT Rearranging this expression gives the expression called the ideal gas law. PV = nRT Ideal Gas Law

52. 52 The universal gas constant, R, can be calculated using the molar volume at STP when calculated at STP, uses a temperature of 273 K, a pressure of 1.00 atm, a quantity of 1.00 mole of a gas, and a molar volume of 22.4 L. P V R = PV = (1.00 atm)(22.4 L) nT (1.00 mole)(273K) n T = 0.0821 L  atm mole  K Universal Gas Constant, R

53. Summary of Units for Ideal Gas Constants 53

54. Ideal Gas Law Problems 1. How many moles of gas are contained in 890.0 mL at 21.0 °C and 750.0 mmHg pressure? 2. 1.09 g of H2 is contained in a 2.00 L container at 20.0 °C. What is the pressure in this container in mmHg? HW is to work on the PhET Gas Laws online activity & complete the worksheet on moodle

55. Focus In (Monday 5/9) Ideal Gas Law R = 0.0821 L  atm mol  K 1. Calculate the volume 3.00 moles of a gas will occupy at 24.0 °C and 762.4 mmHg. 2. What volume will 20.0 g of Argon occupy at STP?

56. Additional help can be found at: http://chemwiki.ucdavis.edu/Core/Physical_C hemistry/Physical_Properties_of_Matter/Stat es_of_Matter/Gases/Gas_Laws/The_Ideal_Ga s_Law http://chemwiki.ucdavis.edu/Core/Physical_C hemistry/Physical_Properties_of_Matter/Stat es_of_Matter/Gases/Gas_Laws/The_Ideal_Ga s_Law The above site goes over each of the equations and their relationships with examples worked out for you to follow or review

57. Guide to Using the Ideal Gas Law 57

58. 58 Unit 6.1 - Gases 6.1.9 Partial Pressure (Dalton’s Law)

59. 59 The partial pressure of a gas is the pressure of each gas in a mixture is the pressure that gas would exert if it were by itself in the container Partial Pressure

60. 60 Dalton’s Law of Partial Pressures indicates that pressure depends on the total number of gas particles, not on the types of particles the total pressure exerted by gases in a mixture is the sum of the partial pressures of those gases P T = P 1 + P 2 + P 3 +..... Dalton’s Law of Partial Pressures

61. Dalton’s Law of Partial Pressures Problems A container holds three gases: oxygen, carbon dioxide, and helium. The partial pressures of the three gases are 2.00 atm, 3.00 atm, and 4.00 atm, respectively. What is the total pressure inside the container?

62. 62 Dalton’s Law of Partial Pressures (continued)

63. 63 For example, at STP, one mole of a pure gas in a volume of 22.4 L will exert the same pressure as one mole of a gas mixture in 22.4 L. Total Pressure 0.5 mole O 2 0.3 mole He 0.2 mole Ar 1.0 mole 1.0 mole N 2 0.4 mole O 2 0.6 mole He 1.0 mole 1.0 atm

64. 64 Scuba Diving When a scuba diver is below the ocean surface, the increased pressure causes more N 2 (g) to dissolve in the blood. If a diver rises too fast, the dissolved N 2 gas can form bubbles in the blood, a dangerous and painful condition called “the bends.” For deep descents, helium, which does not dissolve in the blood, is added to O 2.

65. Guide to Solving for Partial Pressure 65

66. 66 Gases We Breathe The air we breathe is a gas mixture contains mostly N 2 and O 2 and small amounts of other gases

67. 67 Blood Gases In the lungs, O 2 enters the blood, while CO 2 from the blood is released. In the tissues, O 2 enters the cells, which releases CO 2 into the blood.

68. 68 Blood Gases (continued) In the body, O 2 flows into the tissues because the partial pressure of O 2 is higher in blood and lower in the tissues. CO 2 flows out of the tissues because the partial pressure of CO 2 is higher in the tissues and lower in the blood. Partial Pressures (mmHg) in Blood and Tissue Gas Oxygenated Blood Deoxygenated Blood Tissues O 2 100 mmHg 40 mmHg 30 mmHg or less CO 2 40 mmHg 46 mmHg 50 mmHg or greater

69. 69 Changes in Partial Pressures of Blood Gases During Breathing

70. TEST REVIEW (Do in comp book) Pressure and Volume (Boyle’s Law) 1. Boyle’s law states: 2. Boyle’s law is a _________ relationship meaning as _______________ (1 st changing variable) goes up/down, _______________ (2 nd changing variable) goes up/down 3. What are the changing variables of Boyle’s Law? 4. What are the unchanging variables of Boyle’s Law? 5. What is the formula for Boyle’s law? 6. A real-life example of Boyle’s law would be:

71. Temperature and Volume (Charles’s Law) 7. Charles’s law states: 8. Charles’s law is a _________ relationship meaning as _______________ (1 st changing variable) goes up/down, _______________ (2 nd changing variable) goes up/down 9. What are the changing variables of Charles’s Law? 10. What are the unchanging variables of Charles’s Law? 11. What is the formula for Charles’s law? 12. A real-life example of Charles’s law would be:

72. Temperature and Pressure (Gay-Lussac’s Law) 13. Gay-Lussac’s law states: 14. Gay-Lussac’s law is a _________ relationship meaning as _______________ (1 st changing variable) goes up/down, _______________ (2 nd changing variable) goes up/down 15. What are the changing variables of Gay- Lussac’s Law? 16. What are the unchanging variables of Gay- Lussac’s Law? 17. What is the formula for Gay-Lussac’s law? 18. A real-life example of Gay-Lussac’s law would be?

73. The Combined Gas Law 19. What are the changing variables of Boyle’s Law? 20. What are the unchanging variables of Boyle’s Law? 21. What is the formula for the combined gas law?

74. Volume and Moles (Avogadro’s Law) 22. Avogadro’s law states: 23. Avogadro’s law is a _________ relationship meaning as _______________ (1 st changing variable) goes up/down, _______________ (2 nd changing variable) goes up/down 24. What are the changing variables of Avogadro’s Law? 25. What are the unchanging variables of Avogadro’s Law? 26. What is the formula for Avogadro’s law?

75. STP 27. What is standard temperature: __________K, _______ ⁰C 28. What is standard pressure: _________ atm, _________ mmHg, __________ torr 29. 1 mole of gas at STP is _____ L

76. Ideal gas law 30. What is the formula for the ideal gas law? 31. What is R? 32. What is the value of R, and what are the units?

77. Dalton’s Law of Partial Pressure 33. Dalton’s law of partial pressure states: 34. What is the formula for Dalton’s law?

78. Review Videos 1) Crash Course Gas Laws Video (12 minutes) https://www.youtube.com/watch?v=BxUS1K7xu30 2) Bozeman Science Gas Laws video (10 minutes) https://www.youtube.com/watch?v=gmN2fRlQFp4 https://www.youtube.com/watch?v=gmN2fRlQFp4 3) Bozeman Science Ideal Gas Law video (6 minutes) https://www.youtube.com/watch?v=ir64EcRkf5Q https://www.youtube.com/watch?v=ir64EcRkf5Q 4) Khan Academy KMT of gases (15min) https://www.youtube.com/watch?v=Qsa4aAdpHfY 5) The Science Classroom KMT of gases (8 minutes) https://www.youtube.com/watch?v=R1l1Cww88XQ 6) Bozeman Science Gas Pressure (6 minutes) https://www.youtube.com/watch?v=H9VtHkPWNeA