Bell Ringer The gas with the largest volume

Bell Ringer The gas with the largest volume at STP is: A. 10. 0 g He (56. 0 L He) B. 10. 0 g Ne C. 10. 0 g Ar D. 10. 0 g Kr He: 10. 0 g He x 1 mol He 4. 00 g He x 22. 4 L He 1 mol He = 56. 0 L He Source: 2004 VA Chemistry EOC Exam

Bell Ringer The gas with the largest volume at STP is: A. 10. 0 g He (56. 0 L He) B. 10. 0 g Ne (11. 1 L Ne) C. 10. 0 g Ar D. 10. 0 g Kr Ne: 10. 0 g Ne x 1 mol Ne 20. 18 g Ne x 22. 4 L Ne 1 mol Ne = 11. 1 L Ne Source: 2004 VA Chemistry EOC Exam

Bell Ringer The gas with the largest volume at STP is: A. 10. 0 g He (56. 0 L He) B. 10. 0 g Ne (11. 1 L Ne) C. 10. 0 g Ar (5. 61 L Ar) D. 10. 0 g Kr Ar: 10. 0 g Ar x 1 mol Ar 39. 95 g Ar x 22. 4 L Ar 1 mol Ar = 5. 61 L Ar Source: 2004 VA Chemistry EOC Exam

Bell Ringer The gas with the largest volume at STP is: A. 10. 0 g He (56. 0 L He) B. 10. 0 g Ne (11. 1 L Ne) C. 10. 0 g Ar (5. 61 L Ar) D. 10. 0 g Kr (2. 67 L Kr) Kr: 10. 0 g Kr x 1 mol Kr 83. 80 g Kr x 22. 4 L Kr 1 mol Kr = 2. 67 L Kr Source: 2004 VA Chemistry EOC Exam

GAS LAWS Ms. Besal 3/10/2006

Lesson Objectives • • You will be able to: Name and describe 5 characteristics of gases Identify three differences between ideal gases and real gases. Define the term “STP” List 4 units for pressure measurement Explain and describe the relationship between temperature and pressure of gases, according to Charles’ Law. Explain and describe the relationship between volume and pressure of gases, according to Boyle’s Law. Explain how temperature, pressure, and volume of gases are all related according to the combined gas law. Solve mathematic problems about Charles’ Law, Boyle’s Law, and the combined gas law.

What are Characteristics of a GAS?

: Gas Laws In the REAL WORLD: • Gases are fat. (they have mass) • Gases hog the sofa. (they have volume) • Gases are pushy and have an attitude toward other gases. (they exert forces on each other) Image Source: mtv. com In an IDEAL WORLD: • Gases are skinny. (they have no mass) • Gases make themselves invisible. (they have no volume) • Gases are not confrontational. (they do not interact… elastic collisions)

SO FAR… Standard Temperature & Pressure 1 atmosphere 273 K (atm)

What does PRESSURE mean? • In Life: Pressure = a chemistry quiz every day • In Science: Pressure = force per unit area P= F A

How else can we measure Pressure?

SO FAR… Standard Temperature & Pressure 1 atmosphere 273 K (atm)

How can we change Gases? Action Heat it up/Cool it down Variable Temperature Change container size Volume Compress or Decompress Pressure

How are Temperature and Volume Related? Temperature Volume Initial Final T 1 T 2 V 1 V 2

How are Temperature and Volume Related? x x Volume x x x x xx Temperature “At constant pressure… temperature and volume are directly proportional”

Charles’ Law “At constant pressure… temperature and volume are directly proportional. ” V 1 T 1 = V 2 Temperature is always measured in Kelvin! 0ºC = 273 K

How can we change Gases? Action Heat it up/Cool it down Variable Temperature Change container size Volume Compress or Decompress Pressure

How are Volume and Pressure Related? Initial Final Volume V 1 V 2 Pressure P 1 P 2

How are Volume and Pressure Related? x Volume x x x Pressure “At constant temperature… volume and pressure are inversely proportional”

Boyle’s Law “At constant temperature… volume and pressure are inversely proportional. ” P 1 x V 1 = P 2 x V 2

To Recap… • Charles’ Law: Relates Temperature and Volume. V 1 T 1 = V 2 T 2 • Boyle’s Law: Relates Pressure and Volume P 1 x V 1 = P 2 x V 2

…THEREFORE: • Temperature, Volume, and Pressure all related! P 1 V 1 T 1 = P 2 V 2 T 2

Practice 1. 100. 0 cm 3 oxygen at 10. 50 k. Pa changes to 9. 91 k. Pa. What is the new volume of the gas? P 1 V 1 T 1 = P 2 V 2 T 2 P 1 V 1 = P 2 V 2 Boyle’s Law! (10. 50 k. Pa) x (100. 0 cm 3 O 2) = (9. 91 k. Pa) x (V 2) V 2 = (10. 50 k. Pa) x (100. 0 cm 3 O 2) (9. 91 k. Pa) = 106 cm 3 O 2

Practice 2. 150. 0 m. L sulfur dioxide at 748 mm. Hg changes to a new volume of 140. 6 m. L. What is the new pressure of the gas? P 1 V 1 P 2 V 2 = T 1 T 2 P 1 V 1 = P 2 V 2 (748 mm. Hg) x (150. 0 m. L SO 2) = (P 2) x (140. 6 m. L SO 2) P 2 = (748 mm. Hg) (150. 0 m. L SO 2) (140. 6 m. L SO 2) = 798 mm. Hg

Practice 3. 75. 0 cm 3 of hydrogen at 27. 0ºC changed to 10. 0ºC. What is the new volume of the gas? P 1 V 1 T 1 = P 2 V 2 T 2 V 1 V 2 = T 1 T 2 Kelvin! 75. 0 cm 3 H 2 V 2 = 300 K 263 K V 2 = (75. 0 cm 3 H 2) x (263 K) (300 K) – Charles’ Law! = 65. 8 cm 3 H 2

Practice 4. A gas occupies a volume of 0. 560 L. The original temperature was cooled to 7. 71 ºC and the resulting volume was 0. 400 L. What was the original temperature of the gas? P 1 V 1 T 1 0. 560 L T 1 = = P 2 V 2 T 2 0. 400 L = 280. 71 K (0. 560 L) x (280. 71 K) = 393 K 120. ºC (0. 400 L)

Practice 5. 140. L chlorine at 15. 0ºC and 110. 0 k. Pa changed to 40. 0ºC and 123. 5 L. What is the new pressure? P 1 V 1 T 1 (110. 0 k. Pa) (140 L Cl 2) 288 K P 2 V 2 = T 2 = (P 2) (123. 5 L Cl 2) 313 K P 2 = (110. 0 k. Pa) (140. L Cl 2) (313 K) (288 K) (123. 5 L Cl 2) = 136 k. Pa

Practice 6. 500. 0 m. L of hydrogen at 20. 0ºC and 121 k. Pa changed to STP. What is the new volume of the gas? P 1 V 1 P 2 V 2 = T 1 T 2 (120 k. Pa) (500. 0 m. L H 2) = 293 K (101. 3 k. Pa) (V 2) 273 K V 2 = (121 k. Pa) (500. 0 m. L H 2) (273 K) (293 K) (101. 3 k. Pa) = 556 m. L H 2

For Next Class: Homework: Last page of Gas Laws Packet: Problems 1 -10, 11 -25 ODD QUIZ on Charles, Boyle, and Combined Gas Laws 24 points. 3 short answer/FITB problems (2 points each) 3 math problems (6 points each) • 2 points for correct equation • 2 points for correct math • 2 points for correct labels

What Should I Study? • how pressure, temperature, and volume relate to each other in Boyle’s, Charles’, and Combined Gas Laws. • how to determine changing conditions using math (practice problems & homework). • standard conditions of temperature and pressure; how to convert from Celsius to Kelvin, from k. Pa to atm to mm Hg. • how real gases and ideal gases differ.

Lesson Objectives • • You should be able to: Name and describe 5 characteristics of gases Identify three differences between ideal gases and real gases. Define the term “STP” List 4 units for pressure measurement Explain and describe the relationship between temperature and pressure of gases, according to Charles’ Law. Explain and describe the relationship between volume and pressure of gases, according to Boyle’s Law. Explain how temperature, pressure, and volume of gases are all related according to the combined gas law. Solve mathematic problems about Charles’ Law, Boyle’s Law, and the combined gas law.