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States of Matter and Boyle’s Law

States of Matter and Boyle’s Law. Text 9.1: Page 418-428. Uses of Gases. States of Matter. Examples of States. There are examples of elements that exist in each of the 3 states at the room temperature. What Determine State?.

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States of Matter and Boyle’s Law

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  1. States of Matter and Boyle’s Law Text 9.1: Page 418-428

  2. Uses of Gases

  3. States of Matter

  4. Examples of States • There are examples of elements that exist in each of the 3 states at the room temperature

  5. What Determine State? • What state each compound is in is dependent on the strength of the intermolecular bonds • Bond between molecules in the solid state are the strongest of the three • Bond between molecules in the gaseous state are the weakest of the three

  6. Kinetic Molecular Theory • Called this because any moving object has kinetic energy • The energy of movement or motion • Different states are associated with different amounts of kinetic energy

  7. Kinetics of Gases?

  8. Movement of Molecules • Molecules can move in 3 directions • Translational: straight line • Rotational: spinning • Vibrational: back-and-forth motion of atoms within the molecules

  9. Movement of States • If molecules are restricted to vibrational they will stay as solids and in a ordered state • Both gases and liquids will display all 3 types of motion but to different degrees

  10. Movement Between States

  11. Gas Laws: Boyle’s Law • Is a mathematical equation that describes how pressure alters the volume of a gas • p1v1=p2v2

  12. Gas Laws: Boyle’s Law • Is a mathematical equation that describes how pressure alters the volume of a gas • p1v1=p2v2

  13. What Does this Mean? • Relationship between pressure and volume: • As pressure increases, volume decreases • i.e. when pressure is doubled, volume is halved • …as the pressure on a gas increases, the volume of the • gas decreases proportionally, provided that the • temperature and amount of gas stays constant…

  14. What Does this Mean? • Relationship between pressure and volume: • As pressure increases, volume decreases • i.e. when pressure is doubled, volume is halved • …as the pressure on a gas increases, the volume of the • gas decreases proportionally, provided that the • temperature and amount of gas stays constant…

  15. Measure Pressure? • Pressure is measures in Pascal’s (Pa) • This represents I newton (N) on an area of 1 m2 • Atmospheric pressure = 1000 Pa or 1 kPa • Also at times measured in mm Hg because of an instrument we used to use to measure pressure

  16. STP and SATP • For many years did all calculations at STP (standard temperature and pressure) • 0 ⁰ C and 101.325 kPa • Now generally use SATP (standard ambient temperature and pressure • 25⁰ C and 100 kPa • This is also much closer to many laboratory conditions

  17. STP and SATP • For many years did all calculations at STP (standard temperature and pressure) • 0 ⁰ C and 101.325 kPa • Now generally use SATP (standard ambient temperature and pressure • 25⁰ C and 100 kPa • This is also much closer to many laboratory conditions

  18. Practise Problem A 2.0L party balloon at 98 kPa is taken to a top of a mountain where the pressure is 75 kPa. Assume the temperature is the same. What is the new volume of the balloon? (Page 428)

  19. Homework!

  20. Charles', Gay-Lussac’s and Combined Gas Law Text 9.1: Page 429- 438

  21. Learning Goals • By the end of this class, the students will be able to: • Describe how temperature and volume in gases are related in terms of Charles’ Law and kinetic molecular theory • Describe how temperature and pressure in gases are related in terms of Gay-Lussac’s Law and kinetic molecular theory

  22. Gas Laws: Charles’ Law • Is a mathematical equation that describes how temperature alters the volume of a gas • V1 V2 • T1 T 2 =

  23. What Does this Mean? • Relationship between temperature and volume: • As temperature increases, volume increases • i.e. when temperature is doubled, volume is doubled • …as the temperature of a gas increases, the volume of • the gas increases proportionally, provided that the • pressure and amount of gas stays constant…

  24. Temperature • Many times temperature measured in Kelvins • Another unit to measure temperature • Measure from absolute zero • Where there is absolutely no kinetic movement in molecules • K = ⁰ C + 273

  25. Standards • For many years did all calculations at STP (standard temperature and pressure) • 273.15 K (0 ⁰ C) and 101.325 kPa • Now generally use SATP (standard ambient temperature and pressure • 298.15 K (25⁰ C) and 100 kPa • Both of these values of K have more digits but reduced to 3 significant digits

  26. Practise Problems A gas inside a cylinder with a movable piston is heated from 25⁰C to 315 ⁰C . What is the new volume of the gas knowing the initial volume was 0.30L? (Text 433)

  27. Gas Laws: Gay-Lussac’s Law • Is a mathematical equation that describes how temperature alters the pressure of a gas • P1 P2 • T1 T 2 =

  28. What Does this Mean? • Relationship between pressure and temperature: • As temperature increases, pressure increases • i.e. when temperature is doubled, pressure is doubled • …as the temperature of a gas increases, the pressure of • the gas increases proportionally, provided that the • volume and amount of gas stays constant…

  29. Practise Problems A sealed storage tank contains argon gas at 18⁰ C and a pressure of 875 kPa at night. What is the new pressure if the tank and its contents warm to 32⁰ C during the day? (Text 435)

  30. Gas Laws: Combined Gas Law • Is a summary mathematical equation that describes how pressure, temperature and volume all interact • P1 V1 P2V2 • T1 T 2 =

  31. What Does this Mean? • You can use this equation to remember all three of the other equations. • Simple cancel out the variables that stay constant!

  32. Boyle’s Law • P1 V1 P2V2 • T1 T 2 =

  33. Charles’s Law • P1 V1 P2V2 • T1 T 2 =

  34. Gay-Lussac’s Law • P1 V1 P2V2 • T1 T 2 =

  35. Practise Problems A balloon contains hydrogen gas at 20⁰ C and a pressure of 100 kPa and a volume of 7.50L. Calculate the volume of the balloon after it rises to an upper atmosphere with a pressure of 28 kPa and a temperature of -36 ⁰ C ? (Text 437)

  36. Mixtures, Partial Pressures and Reactions Text 10.1-10.2: Pages 460-471

  37. Mixtures of Gases • Many years ago scientists believed that the atmosphere was made of only one chemical compound • Antoine Lavoisier (1743-1794) was the first to give evidence that the atmosphere was made of a mixture of gases • He was also known as the father of modern chemistry

  38. Antoine Lavoisier • He did a series of experiments that involved burning different compounds in the presence of air • Based on these experiments he concluded the atmosphere was made of at least 2 gases • One that supported combustion and one that did not

  39. Antoine Lavoisier • Lavoisier also noticed if he burned something in a sealed container when that container was opened to air would rush in • This is because there was a lower pressure in the container because of the volume of gas consumed in the combustion

  40. John Dalton • John Dalton more specifically did work on the properties of gases • He hypothesized that gas molecules work independently and will produce the same pressure whether in a mixture or on its own

  41. Experimental Design

  42. Dalton’s Law of Partial Pressures • From his experiments he came up with his law… • A partial pressure , p, a gas in a mixture would exert if it were the only gas present in the same volume and at the same temperature “The total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases” • ptotal= p1 + p2 + p3 … pn

  43. Kinetic Molecular Theory… Again? • This law can be explained via kinetic molecular theory • The collisions are what cause the pressure • It doesn’t matter what type of gaseous molecules are causing the collisions, just that a specific number of collisions are happening

  44. Practise Problems “ A compressed air tank for scuba diving to a depth of 30 m, a mixture with an oxygen partial pressure of 28 atm and a nitrogen partial pressure of 110 atm is used. What is the total pressure of the tank?” (Page 461)

  45. Reactions of Gases • Even though gases occur in mixtures around us, they also can react with one another! • But always follow The Law of Combining Volumes • Volumes of gases combine according to mole ratios • “When measured at the same temperature and pressure, volumes of gaseous reactants and products of chemical reactions are always in simple ratios of whole numbers”

  46. Avogadro’s Theory • Even more fully explained by Avogadro’s Theory • “Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules” • Thus we can still use mole ratios to predict volumes of products produced in chemical equations

  47. Practise Problems “A catalytic converter in the exhaust system of a car uses oxygen (from the air) to convert carbon monoxide to carbon dioxide, which is released through the tailpipe. If we assume the same temperature and pressure, what volume of oxygen is required to react with 125 L of carbon monoxide produced during a 100km trip?” (Page 468)

  48. Moles of Gases?!? • We can determine moles of a gas from the volume it takes up • Molar volume (MV): is the volume that one mole of a gas takes up at a specified temperature and pressure At SATP 24.8 L/molAt STP 22.4 L/mol • n = V / MV • Or • Moles = volume / molar volume

  49. Practise Problem “What volume is occupied by 0.024 mol of carbon dioxide gas at SATP?” (Page 469)

  50. Ideal Gas Law Text 9.4: Page 443-445

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