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Gases Chapter 10/11 Modern Chemistry

Gases Chapter 10/11 Modern Chemistry. Sections 10.1, 11.1-11.3 The Kinetic Molecular Theory of Matter Gases and Pressure The Gas Laws Gas Volumes and the Ideal Gas Law. Section 11.1. Gases and Pressure. Pressure. Pressure = force (in Newtons) per unit area

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Gases Chapter 10/11 Modern Chemistry

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  1. GasesChapter 10/11Modern Chemistry Sections 10.1, 11.1-11.3 The Kinetic Molecular Theory of Matter Gases and Pressure The Gas Laws Gas Volumes and the Ideal Gas Law Chapter 8 Section 1 Describing Chemical Reactions p. 261-275

  2. Section 11.1 Gases and Pressure Chapter 11Section 1 Gases & Pressure p. 361-368

  3. Pressure • Pressure = force (in Newtons) per unit area • Pressure of a gas is caused by particles of a gas colliding with the walls of its container • Pressure (P) of a gas depends on volume (V), temperature (T), and the number of particles (n). Chapter 11Section 1 Gases & Pressure p. 361-368

  4. Pressure & Amount of Gas Insert Holt Visualizing Matter Disc 2 Chapter 11Section 1 Gases & Pressure p. 361-368

  5. Atomospheric Pressure • The atmosphere exerts pressure. • 78% N, 21% O, 1% other • Atmospheric pressure is the sum of the individual pressures of the gases. Chapter 11Section 1 Gases & Pressure p. 361-368

  6. Measuring Pressure • Barometer: a device used to measure atmospheric pressure. • Developed by Evangelista Torricelli in the early 1600s. Chapter 11Section 1 Gases & Pressure p. 361-368 p. 363

  7. Mercury Barometer p. 363 Chapter 11Section 1 Gases & Pressure p. 361-368

  8. Aneroid Barometer The aneroid barometer is operated by a metal cell containing only a very small amount of air, or a series of such cells joined together. Increased air pressure causes the sides of the cell or cells to come closer together. One side is fixed to the base of the instrument while the other is connected by means of a system of levers and pulleys to a rotating pointer that moves over a scale on the face of the instrument. Chapter 11Section 1 Gases & Pressure p. 361-368

  9. Measuring Pressure • A manometer measures the pressure of a gas in a flask. Chapter 11Section 1 Gases & Pressure p. 361-368 p. 363

  10. Manometer Chapter 11Section 1 Gases & Pressure p. 361-368

  11. Units of Pressure The average atmospheric pressure at sea level at 0°C. • 760 mm Hg – millimeters of mercury • 1.00 atm – atmospheres • 101.325 kPa – kilopascals (SI Units) 1 pascal is the pressure exerted by a force of 1 Newton acting on an area of 1 square meter See the table on page 364 Chapter 11Section 1 Gases & Pressure p. 361-368

  12. Table 1 Units of Pressure p. 364 Chapter 11 Section 1 Gases & Pressure p. 361-368

  13. Converting Pressure Units • The average atmospheric pressure in Denver, Colorado, is 0.830 atm. Express this pressure in (a) millimeters of mercury (mm Hg) and (b) kilopascals (kPa). p. 365 a. 631 mm Hg b. 84.1 kPa Chapter 11Section 1 Gases & Pressure p. 361-368

  14. Practice Problems p. 365 • Convert a pressure of 1.75 atm to kPa and to mm Hg. • The critical pressure of carbon dioxide is 72.7 atm. What is this value in units of pascals? p. 365 • 177 kPa, 1330 mm Hg • 2. 7.37 × 106 Pa Chapter 11Section 1 Gases & Pressure p. 361-368

  15. Dalton’s Law of Partial Pressures • Partial Pressure: The pressure of each gas in a mixture • Dalton’s Law of Partial Pressures: The total pressure of a gas mixture is the sum of the partial pressures of the component gases. PT = p1 + p2 + p3 … Chapter 11Section 1 Gases & Pressure p. 361-368

  16. Partial Pressures Chapter 11Section 1 Gases & Pressure p. 361-368

  17. Law of Partial Pressures p. 363 Chapter 11Section 1 Gases & Pressure p. 361-368

  18. p. 366 Gases Collected by Water Displacement Chapter 11Section 1 Gases & Pressure p. 361-368

  19. Gases Collected by Water Displacement • A gas collected over water is a mixture of the gas and water vapor • The pressure water exerts is called vapor pressure Insert Holt Visualizing Matter Disc 2 Chapter 11Section 1 Gases & Pressure p. 361-368

  20. Gases Collected by Water Displacement atm atm • When the water levels inside and outside the tube are the same the PT = Patm Patm = pgas + pH2O or pgas =Patm - pH2O atm atm PT<Patm PT=Patm PT>Patm Chapter 11Section 1 Gases & Pressure p. 361-368

  21. Gases Collected by Water Displacement • The vapor pressure of water varies with temp. p. 859 Chapter 11Section 1 Gases & Pressure p. 361-368

  22. Dalton’s Law Problems • Oxygen gas from the decomposition of potassium chlorate, KClO3, was collected by water displacement. The barometric pressure and the temperature during the experiment were 731.0 mm Hg and 20.0°C, respectively. What was the partial pressure of the oxygen collected? p. 367 1. 713.5 mm Hg Chapter 11Section 1 Gases & Pressure p. 361-368

  23. Practice Problems p. 367 • Some hydrogen gas is collected over water at 20.0°C.The levels of water inside and outside the gas-collection bottle are the same. The partial pressure of hydrogen is 742.5 mm Hg.What is the barometric pressure at the time the gas is collected? p. 367 1. 760.0 mm Hg Chapter 11Section 1 Gases & Pressure p. 361-368

  24. Boyle’s Law TEMP. TEMP. PRESSURE AMOUNT AMOUNT VOLUME Chapter 11 Section 2 The Gas Laws p. 369-377

  25. Boyle’s Law • P & V relationship; n & T held constant • “The volume of a fixed mass of gas varies inversely with the pressure at constant temperature.” Insert Glencoe Chemistry Matter Disc 2 Chapter 11 Section 2 The Gas Laws p. 369-377 p. 369

  26. Boyle’s Law PV = kk is a constant P1 V1 = k P2 V2 = k P1 V1 = P2 V2 V1 V2 P1 P2 Chapter 11 Section 2 The Gas Laws p. 369-377 p. 370

  27. Boyle’s Law Problem • A sample of oxygen gas has a volume of 150.0 mL when its pressure is 0.947 atm. What will the volume of the gas be at a pressure of 0.987 atm if the temperature remains constant? p. 370 1. 144 mL O2 Chapter 11 Section 2 The Gas Laws p. 369-377

  28. Charles’ Law TEMP. PRESSURE PRESSURE AMOUNT AMOUNT VOLUME Chapter 11 Section 2 The Gas Laws p. 369-377

  29. Kelvin Temperature Scale • Same size degrees as the Celcius scale • 0 K = -273.15° C • 0 K = absolute zero • K = 273 + °C Chapter 11 Section 2 The Gas Laws p. 369-377

  30. Charles’ Law • V & T relationship; n & P held constant • The volume of a fixed mass of gas at constant pressure varies directly with the Kelvin temperature.” Insert Glencoe Chemistry Matter Disc 2 Chapter 11 Section 2 The Gas Laws p. 369-377

  31. Charles’ Law V / T = k k = a constant V1 / T1 = k V2 / T2 = k V1 = V2 T1 = T2 V2 V1 T1 T2 Chapter 11 Section 2 The Gas Laws p. 369-377 p. 372

  32. Charles’ Law Problem • A sample of neon gas occupies a volume of 752 mL at 25°C. What volume will the gas occupy at 50°C if the pressure remains constant? p. 372 1. 815 mL Ne Chapter 11 Section 2 The Gas Laws p. 369-377

  33. Combined Gas Law TEMP. PRESSURE AMOUNT AMOUNT VOLUME Chapter 11 Section 2 The Gas Laws p. 369-377

  34. P V P V 1 1 2 2 T T 1 2 Combined Gas Law • P, V and T relationship; n held constant • “The combined gas law expresses the relationship between pressure, volume and temperature of a fixed amount of gas.” = Chapter 11 Section 2 The Gas Laws p. 369-377

  35. STP Standard Temperature and Pressure Standard Pressure 1.00 atm 760 mm Hg 101.325 kPa Standard Temperature 273 K 0° C Chapter 11 Section 2 The Gas Laws p. 369-377

  36. Combined Gas Law Problems • A helium-filled balloon has a volume of 50.0 L at 25°C and 1.08 atm. What volume will it have at 0.855 atm and 10.0°C? p. 375 1. 60.0 L He Chapter 11 Section 2 The Gas Laws p. 369-377

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