CHEM 1211 Lecture 14 Outline of Last Lecture I Table One II Enthalpy III Calorimetry IV Hess s Law Outline of Current Lecture I Hess s law continued II Chapter 6 Atoms Electronic Structure III Color in Neon Lights Fireworks etc A Properties of Light photon IV Constant Frequency Variable Wavelength A Photoelectric Effect B Light Energy Current Lecture I Hess s law continued H f 1N2 g O2 G 1N2O g 1Na s Cl2 g 1NaCl s Use standard states EXOTHERMIC H rxn n H f products n H f reactants Trying to get to low energy state 1 H C3H8 104 7 KJ mol H CO2 393 5 KJ mol H O2 0 0 KJ mol H H2O 285 8 KJ mol Calculate the H 298 for this reaction C3H8 g 5O2 g 3CO2 g 4H2O l H rxn 3 393 5 4 285 8 1 104 7 H rxn 2 219 KJ mol EXOTHERMIC II III IV Chapter 6 Atoms Electronic Structure Color in Neon Lights Fireworks etc Use Barium Copper Strontium molecular compounds lightning bugs A Properties of Light photon Osolating electric field Wavelength m cm nm A A 1 x 10 10m or 1 x 10 8cm Period unit is seconds Frequency V 1 P V Frequency of Hertz Hz P Period Velocity v u wavelength U frequency in Hz V velocity in m s or cm s EX VACUUM 3 0 x 108 m s or 3 0 x 1010 cm s Constant Frequency Variable Wavelength Distance Frequency of photon is constant A Photoelectric Effect lights can strike the surface of some metals causing an e to be ejected Work fxn hvo WAVE PARTICLE DUALITY B Light Energy 1900 Max Planck black body radiation 1 Energy is quantized 2 Light has particle character E hv or E hc or E nhv H 6 626 x 10 34 J x S Ephoton or 1
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