Student Notes CHM_115_F09_lecture 3 (revised).ppt

For Next Lecture Read in KTT: Sections 23.1 thru 23.3 REMINDER Watch the safety video and pass the Safety Quiz (Blackboard) before lab next week. HW due Friday: OWL: http://www.cengage.com/owl CHM 11500-M Lecture 3 Dr. John Polles Lectures: M, F Section M-01 at 11:30 AM Section M-02 at 2:30 PM Earth?s Energy Balance Surface heat gain = 168 + 324 = 492 Watts per square meter Surface heat loss = 24 + 78 + 390 = 492 W m-2 CO2 Increase from 1958 to 2004 IPCC report is based on models The variables in various IPCC models include: Population growth rate Economic development Energy use Efficiency of energy use Mix of energy technologies See the IPCC Report on Blackboard for more details. Models using only natural forcings Models using both natural and anthropogenic forcings Observed Global and Continental Temperature Change The Big Picture Data have been collected that demonstrate: Global average air temperatures rising Global average ocean temperatures rising Sea ice extent is decreasing Snow and glacial coverage is decreasing Global average sea level is rising CO2 levels increasing faster than can be accounted for by non-human natural sources CO2 is a greenhouse gas with the highest radiative forcing values (due to its IR absorption abilities) Global warming and related climate change caused by human activity is a model consistent with these data. Base Units The joule is not a fundamental unit. Joule is the energy unit. 1 J = 1 kg ( m2/s2) Question #1 Which is a unit of temperature? ampere (A) gram (g) joule (J) kelvin (K) mole (mol) Question #2 Which is the largest unit of energy? J kJ mJ MJ nJ pJ Potential and Kinetic Energy Energy is stored in molecules. As stored energy it is potential energy. Some molecules store more than others. When a fuel is burned, potential energy is converted to kinetic energy. The amount of kinetic energy you can get out depends on the amount of potential energy available Energy is neither created nor destroyed, it is only converted between forms. Question #3 Which has the greater kinetic energy? KE = ½ m v2 Gases The particles (molecules or atoms) in a gas are Far apart Move randomly gases liquids solids changes changes volume: shape: changes constant constant constant Pressure Caused by collisions of atoms/molecules with walls of container Pressure is force per unit area SI unit of pressure: Pa (pascal) 1 Pa = 1 N/m2 1 atm = 101,325 Pa atm = 1 torr = 1 mm Hg = 133 .322 Pa Dalton?s Law of Partial Pressures For a mixture of unreacting gases the total pressure is the sum of the individual pressures Ptotal = Pgas1 + Pgas2 + ... Pgas1 = (1/V) ngas1 R T The Ideal Gas Law P V = n R T P = pressure (atm) V = volume (L) n = number of moles (no units) T = temperature (K) R = gas constant For these units = 0.08205 (atm L)/(mol K) DO NOT USE 8.314 J/(mol K)