CHEM 251 1st Edition Lecture 10 Outline of Last Lecture I. Clicker QuestionsII. Intro to SymmetryIII. Symmetry OperationsOutline of Current Lecture IV. Clicker QuestionV. Group ProblemVI. ApplicationsVII. Hydrogen EconomyCurrent LectureVIII. Clicker Questiona. How many vertical planes? 3b. Assign the point group: C1III. Group Problema. Identify point group, symmetry operations, z-axis: C3h; C3, h, E, S3; coming out of pageThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Ohc. Csd. D3he. C2v IV. Applicationsa. Spectroscopyi. Molecular symmetry determines # vibrations observed by IR or Raman specii. IR spec does not detect totally symmetric vibrationsiii. Greenhouse gases like CO2 absorb IR and trap it in atmosphere b. Polarityi. Highly symmetric molecules have no dipole momentii. Lower symmetry molecules tend to be less polarc. Chiralityi. Cn and Dn point groups always chiral (no mirror plane)ii. But C2v / C2h etc. achiralV. The Hydrogen Economya. H-H bond: strong, non-polarized => unreactive gasi. MO diagram: symmetric, energy matching and overlapb. Combustion produces waterc. High energy density / moled. Cleanest burning fuele. Drawbacks: forms explosive mixtures w/ air between 5% and 95% f. Low volumetric energy densityg. No sustainable and scalable methods to produceh. World’s largest use of H2: Haber-Bosch Process i. N2 + 2H2 => 2NH3 ii. 1% of world’s energy goes into making ammoniaiii. used to synthesize fertilizers, enabled efficient crop growth to sustain larger world
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