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Chemistry 100(02) Fall 2013

Chemistry 100(02) Fall 2013. Instructor: Dr. Upali Siriwardane e-mail : upali@coes.latech.edu Office : CTH 311 Phone 257-4941 Office Hours : M,W, 8:00-9:30 & 11:30-12:30 a.m Tu,Th,F 8 :00 - 10:00 a.m.   Or by appointment Test Dates :.

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Chemistry 100(02) Fall 2013

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  1. Chemistry 100(02) Fall 2013 Instructor: Dr. UpaliSiriwardane e-mail: upali@coes.latech.edu Office: CTH 311 Phone257-4941 Office Hours: M,W, 8:00-9:30 & 11:30-12:30 a.m Tu,Th,F8:00 - 10:00 a.m.   Or by appointment Test Dates: September 30, 2013 (Test 1): Chapter 1 & 2 October 23, 2013 (Test 2): Chapter 3 & 4 November 13, 2013 (Test 3) Chapter 5 & 6 November 14, 2013 (Make-up test) comprehensive: Chapters 1-6 9:30-10:45:15 AM, CTH 328

  2. Text Book & Resources REQUIRED : Textbook: Principles of Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro - Pearson Prentice Hall and also purchase the Mastering Chemistry Group Homework, Slides and Exam review guides and sample exam questions are available online: http://moodle.latech.edu/ and follow the course information links. OPTIONAL : Study Guide: Chemistry: A Molecular Approach, 2nd Edition- Nivaldo J. Tro 2nd Edition Student Solutions Manual: Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro 2nd Page-2. CHEM 100 Chapter 5.

  3. Chapter 5. Gases 5.1 Breathing: Putting Pressure to Work . 179 5.2 Pressure: The Result of Molecular Collisions . 180 5.3 The Simple Gas Laws: Boyle’s Law, Charles’s Law, and Avogadro’s Law 183 5.4 The Ideal Gas Law 190 5.5 Applications of the Ideal Gas Law: Molar Volume, Density, and Molar Mass of a Gas 193 5.6 Mixtures of Gases and Partial Pressures ..197 5.7 Gases in Chemical Reactions: Stoichiometry Revisited 203 5.8 Kinetic Molecular Theory: A Model for Gases .206 5.9 Mean Free Path, Diffusion, and Effusion of Gases 212 5.10 Real Gases: The Effects of Size and Intermolecular Forces 214 5.11 Chemistry of the Atmosphere: Air Pollution and Ozone Depletion 217 Page-3. CHEM 100 Chapter 5.

  4. Chapter 5. KEY CONCEPTS • .Describe the use of Gram’s Law of effusion • Real Gases: The Effects of Size and Intermolecular Forces • Chemistry of the Atmosphere: Air Pollution and Ozone Depletion and CFC in it • Page-4. • Components of the atmosphere • Industrial pollution and urban pollution • Global Warming • Pressure: Molecular Collisions • Kinetic-molecular theory and use the Properties of gases • The Gas Laws: Boyle’s Law, Charles’s Law, and Avogadro’s Law • The Ideal Gas Law • Molar Volume, Density, and Molar Mass of a Gas • Mixtures of Gases and Partial Pressures • Daltons Law of partial pressure • Stoichiometry in gases in Chemical Reactions • Mean Free Path, Diffusion, and Effusion of Gases • CHEM 100 Chapter 5.

  5. General Characteristics of Gases • There is a lot of “free” space in a • gas. • Gases can be expanded infinitely. • Gases occupy containers • uniformly and completely. • Gases diffuse and mix rapidly and • randomly. • Gases are the most disordered of • the phases of matter. • Page-5. • CHEM 100 Chapter 5.

  6. Characteristics of Gases • Gases expand to fill any container. • – random motion, no attraction • Gases are fluids (like liquids). • – but no attraction between particles • Gases have very low densities. • – no volume = lots of empty space CHEM 100 Chapter 5.

  7. 1. What is gaseous state? How it is different from liquid and solid state? Page-7. CHEM 100 Chapter 5.

  8. Characteristics of Gases • Gases can be compressed. • – no volume = lots of empty space • Gases undergo diffusion & effusion. • – random motion • Page-8. • CHEM 100 Chapter 5.

  9. Temperature CHEM 100 Chapter 5. • Always use absolute temperature • (Kelvin) when working with gases. • °F • -459 32 212 • °C • -273 0 100 • K • 0 273 373 ° = 5 ° - C 9 ( F 32) K = °C + 273

  10. Standard Temperature & Pressure 0°C 273 K -OR- 1 atm 101.325 kPa Page-10. CHEM 100 Chapter 5.

  11. 2. What are the properties of gases and how they are measured? Page-11. CHEM 100 Chapter 5.

  12. Components of the atmosphere ThiE IR MCI PHERE 0.001 Mb 0.01 b MES 0,5 ,HERE 0.1 Mb 70 60 40 rrii. .or a0 - l•Ip1 02011e m LxiMurro -- - - eri b- -$0 S TRA TOSPI-E RE mb 20 Sfratopause 12e. i no 90 94 CI .r• 14 it • TOW Clf) rav • 1 CFO -HO 120 Temperature 20 40 80 60 'C 1 ••i- 0 -20 0 4 0 -60 -10 -80 .40 Page-12. CHEM 100 Chapter 5.

  13. Industrial pollution and urban pollution Ozone Particulate Matter Carbon Monoxide Nitrogen Oxides Sulfur Dioxide Lead Page-13. CHEM 100 Chapter 5.

  14. Kinetic Molecu lar Theory Particles in an ideal gas... – In constant motion. – have no volume. – have elastic collisions. – are in constant, random, straight-line motion. – don’t attract or repel each other. – have an avg. KE directly related to Kelvin temperature. Page-14. CHEM 100 Chapter 5.

  15. Real Gases • Particles in a REAL gas... • – have their own volume • – attract each other • Gas behavior is most ideal... • – at low pressures • – at high temperatures • – in nonpolar atoms/molecules Page-15. CHEM 100 Chapter 5.

  16. Properties of Gases P = pressure (atmospheres) • • V = volume of the gas (L) • T = temperature (K) • n = amount (moles) Page-16. CHEM 100 Chapter 5.

  17. CHEM 100 Chapter 5. Kinetic Theory of Gases Page-17.

  18. Pressure and Torricelli barometer Column height measures P of atmosphere. 1 standard atm = 760 mm Hg = 760 torr = 29.9 inches Hg = about 34 feet of water SI unit is PASCAL, Pa, where 1 atm = 101.325 kPa. 18. CHEM 100 Chapter 5.

  19. 3. What is a Torricelli barometer and how it measures atmospheric pressure? Page-19. CHEM 100 Chapter 5.

  20. Pressure Manometer – measures contained gas pressure

  21. Common Units of Pressure Page-21. CHEM 100 Chapter 5.

  22. 4. One atmosphere of pressure is equal to 760 mmHg. This unit is used in the common barometer and manometer. Determine height (in mm) of a column of liquid bromine if the pressure is one atmosphere. The densities of mercury and bromine are 13.546 and 3.119 g/cm3, respectively. Page-22. CHEM 100 Chapter 5.

  23. The Gas Laws • Simple Gas Laws • Boyle’s Law: PV = k; P = k 1/V • Charles’s Law: V = k T; V/T= k • Avogadro’s Law V = k n; V/n = k • Complex Gas Laws • Gay-Lassac’s Law; PV/T = k; • Ideal Gas Law; PV/nT = R; PV = n RT Page-23. CHEM 100 Chapter 5.

  24. P 1/V = k 1/V PV = k = (nRT) P1V1 = P2V2 Page-24.

  25. CHEM 100 Chapter 5. Charles’s Law Page-25. V T = k T • If amount (n) and • pressure (P) are held • constant, then • V and T are directly • related. V2 T2 V = kT V1 T1 =

  26. Page-26. CHEM 100 Chapter 5.

  27. CHEM 100 Chapter 5. Avogadro’s Principle • Equal volumes of gases contain • equal numbers of moles • –at constant temp & pressure • –true for any gas n Page-27. V V n k V1 n1 V2 = n2

  28. Volume of a Gas at STP Molar Volume is 22.4 L at Standard Temperature & Pressure 0°C 273 K -OR- 1 atm 101.325 kPa Page-28. CHEM 100 Chapter 5.

  29. Gay-Lussac’s Law • The pressure and absolute • temperature (K) of a gas are • directly related • – at constant mass & volume T P k P1 T1 T P2 T2 = Page-29. CHEM 100 Chapter 5.

  30. Combined Gas Law PV T P1V1T2 = P2V2T1 P1V1 T1 = = k P2V2 T2 Page-30. CHEM 100 Chapter 5.

  31. Ideal Gas Law constant n and T constant n and P constant P and T PV = nRT ar I 1 V a P Boyle's Law ) V a T Van Charles's Law Avogadro's Law .) L } Page-31. CHEM 100 Chapter 5.

  32. 5. What are gas laws? Boyle's Law: Charles Law: Combined gas Law: Avogadro's Law: Ideal gas Law: . Page-32. CHEM 100 Chapter 5.

  33. 6. What are the postulates of Kinetic Molecular Theory that has been used to explain behavior of gases (gas laws)?. Page-33. CHEM 100 Chapter 5.

  34. 7. The volume of a sample of gas is 750. mL at STP. What volume will the sample occupy at 0.0 C and 950. torr? Page-34. CHEM 100 Chapter 5.

  35. 8. A 2.00-L flasks at 25 C and 730 torr contain CH4 (methane) gas, how many moles of gas are in the flask? Page-35. CHEM 100 Chapter 5.

  36. 9. A nitrogen sample has a volume of 5.00 L at 30oC and 750.0 torr. How many nitrogen atoms does it contain? Page-36. CHEM 100 Chapter 5.

  37. 10. What volume will 32.0 g of O2 occupy at STP? Page-37. CHEM 100 Chapter 5.

  38. 11. A 2.00-g piece of solid CO2 (dry ice) is allowed to sublime in a balloon. The final volume of the balloon is 2.00 L at 303 K. What is the pressure of the gas? Page-38. CHEM 100 Chapter 5.

  39. Using PV = nRT Problem: How many moles of N2 are needed to fill a small room with a volume of 960 cubic feet to P = 745 mm Hg at 25.0 oC? Step 1: Get all data into proper units. V = 960 ft3 = 27,000 L 960 ft3 x (12 in/1 ft)3 x (2.54 cm/1 in)3 x (1 mL/1 cm3) x (1 L/1000 mL) T = 25 oC + 273 = 298 K P = 745 mm Hg = 0.980 atm 745 mm Hg (1 atm/760 mm Hg) Page-39. CHEM 100 Chapter 5.

  40. Step 2: Now calculate moles using ideal gas law. n = PV / RT R = 0.082057 L•atm/K•mol is the ideal gas constant. (0.0821 L atm/K mol)(298K) n = (0.980 atm) (2.7 x 104 L) n = 1.1 x 103 mol (or about 30 kg of gas) Page-40. CHEM 100 Chapter 5.

  41. PV V nT n R = k UNIVERSAL GAS CONSTANT R=0.0821 Latm/molK R=8.315 dm3kPa/molK Page-41. Idea l Gas Law CHEM 100 Chapter 5.

  42. Ideal Gas Law PV=nRT UNIVERSAL GAS CONSTANT R=0.0821 Latm/molK R=8.315 dm3kPa/molK Page-42. CHEM 100 Chapter 5.

  43. Idea Gas Law • Calculate the pressure in atmospheres • of 0.412 mol of He at 16°C & occupying • 3.25 L. IDEAL GAS LAW CHEM 100 Chapter 5.

  44. GIVEN: WORK: V = ? n = 85 g = 2.7 mol Find the volume of 85 g of O2 at 25°C and 104.5 kPa. IDEAL GAS LAW Ideal Gas Law 85 g 1 mol = 2.7 mol 32.00 g PV = nRT (104.5)V=(2.7) (8.315) (298) kPa mol dm3kPa/molK K V = 64 dm3 T = 25°C = 298 K P = 104.5 kPa R = 8.315 dm3kPa/molK

  45. Gas Law Problems A gas occupies 473 cm3 at 36°C. Find its volume at 94°C. CHARLES’ LAW .

  46. Gas Law Problems • A gas occupies 100. mL at 150. kPa. • Find its volume at 200. kPa. • BOYLE’S LAW .

  47. A gas occupies 7.84 cm3 at 71.8 kPa & • 25°C. Find its volume at STP. • COMBINED GAS LAW Gas Law Problems WORK: P1V1T2 = P2V2T1 (71.8 kPa)(7.84 cm3)(273 K) =(101.325 kPa) V2 (298 K) V2 = 5.09 cm3 GIVEN: P T V V1 = 7.84 cm3 P1 = 71.8 kPa T1 = 25°C = 298 K V2 = ? P2 = 101.325 kPa T2 = 273 K CHEM pter .

  48. E. Gas Law Problems • A gas’ pressure is 765 torr at 23°C. At • what temperature will the pressure be • 560. torr? • GAY-LUSSAC’S LAW • .

  49. Gas Density and Molecular Mass Relationship in the Ideal Gas Law Page-49. • MM = gRT/PV • MM = dRT/P • where d = density (mass/volume) • PV = gRT / MM • n = g/MM • where MM is molar mass grams/volume is density CHEM 100 Chapter 5.

  50. Gas Density and Molecular Mass Relationship in the Ideal Gas Law Density n V virs<1 Molar density Molar mass PM d RT Page-50. CHEM 100 Chapter 5.

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