1 / 17

Unit 5: Gas and Atmospheric Chemistry

Unit 5: Gas and Atmospheric Chemistry. 11.2 & 11.3 Gas Laws. Context. In a gas, the particles are very far apart This means that there is a lot of empty space between them This makes gases compressible. Consider this….

eunice
Download Presentation

Unit 5: Gas and Atmospheric Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Unit 5: Gas and Atmospheric Chemistry 11.2 & 11.3 Gas Laws

  2. Context • In a gas, the particles are very far apart • This means that there is a lot of empty space between them • This makes gases compressible

  3. Consider this… • What happens to the volume of a gas when you increase the pressure? Ex: press a syringe that is stoppered) • Why? • Gases are compressible

  4. Animation • http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law_graph.html

  5. Boyle’s Law • In the 17th, Robert Boyle described this as “the spring in the air” • As pressure on a gas increases, the volume of the gas decreases proportionally, if temperature and amount of gas (moles) remain constant. • P α 1/V • PV = k P1V1 = P2V2

  6. Example Problem • A 550 L weather balloon at 98 kPa is released from the ground and rises into the atmosphere. It is caught a later height and instruments indicate the air pressure is 75 kPa. What is the volume of the captured balloon? P1= V1= P2= V2= 98 kPa 550 L 75kPa ? P1V1=P2V2 (98 kPa)(550L) = (75 kPa)(V2) V2= 719 L

  7. Real Life Applications • Scuba Diving • As they dive down underwater, the pressure increases  volume? • What happens to volume as you ascend in water? • Ears popping!

  8. Charles’ Law Temperature and Volume

  9. Absolute Zero • This temperature is absolute zero, the lowest possible temperature. • A theoretical temperature at which matter has no kinetic energy (volume of 0) and therefore transmit no thermal energy. • -273.15 ˚C

  10. Temperature Scales Kelvin devised a new scale that would have no negative values • 1˚C = 1 K • ˚C = K - 273.15 • K = ˚C + 273.15 In this unit, we will ALWAYS use K

  11. Charles’ Law As the temperature of a gas increases, the volume increases proportionally, when pressure and amount of gas (moles) remains constant. Temperature (in Kelvins) is directly proportional to volume A direct relationship V α T V = kT Vi = Vf Ti Tf

  12. V1 = V2 T1 T2 Charles’ Law Ex. A balloon with a volume of 1.0L at 25°C is cooled to -190°C. The new volume is… V1 = V2V1= 1.0L T1 = 25 + 273 = 298K T1 T2 T2 = -190 + 273 = 83K V2 = 1.0 L x 83 K 298K V2 = 0.28L = 280mL

  13. Pressure and Temperature: Gay-Lussacs Law Pressure increases proportionally as temperature increases, provided volume and amount remain constant. Pressure is directly proportional to temperature (in Kelvins) P  T A direct relationship P = kT P = k T P1 = P2 T1 T2

  14. Example Ex. A gas cylinder with a pressure of 1000kPa at 25°C is placed in a boiling water bath. What will the new pressure reading be? P1 = P2 P1 = 1000kPa T1 = 25 + 273 = 298K T1 T2 P2 = ? T2 = 100 + 273 = 373K P2 = 1000kPa x 373 K 298 K P2 = 1252 kPa

  15. Video!

  16. Practice!! • Popsicle stick analogy • P. 435 # 2,5 • P. 451 # 2-5 • Worksheet – “Problems – Gas Laws”

More Related