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Unformatted text preview: 1 CHM151 University of Toronto Chapter 21 Electrochemistry: Chemical Change and Electrical Work CHM151 University of Toronto Electrochemistry: Chemical Change and Electrical Work 21.1 Half-Reactions and Electrochemical Cells 21.2 Voltaic Cells: Using Spontaneous Reactions to Generate Electrical Energy 21.3 Cell Potential: Output of a Voltaic Cell 21.4 Free Energy and Electrical Work 21.5 Electrochemical Processes in Batteries 21.6 Corrosion: A Case of Environmental Electrochemistry 21.7 Electrolytic Cells: Using Electrical Energy to Drive a Nonspontaneous Reaction CHM151 University of Toronto Suggested Problems Chapter 21: 1, 3, 10, 12, 14, 16, 21, 22, 26, 29, 36, 37, 40, 42, 44, 48, 53, 55, 58, 60, 62, 64, 70, 74, 76, 78, 80, 81, 83, 86, 87, 101, 103, 105, 111, 116, 118, 119, 122, 125, 127, 129, 134, 138, 146, 148, 153, 156 Do additional problems as needed to reinforce material. Be able to: Balance redox equations, calculate cell potentials and different permutation of using standard reduced cell potentials, calculate equilibrium constants from cell potentials, know connection between free energy and cell potentials, use of Nernst equation for nonstandard conditions and quantify electrochemical reactions re: use of current/moles of reactant/product/mass CHM151 University of Toronto Take Home Lessons Take Home Lessons First Lecture: Basic Overview of Electrochemistry Oxidation and Reduction or Redox chemistry (electron book keeping) History of electrochemistry (and incidentally electricity) redox chemistry on the move Basic elements of an electrochemical cell 2 CHM151 University of Toronto Scientific Motivation* Scientific Motivation* Electrochemistry Electrochemistry Energy = work (all activities/quality of life) Fossil fuels projected to be significantly depleted between 2060 - 2100 Most of the human race still unaffected by all the progress made in science Equivalent to one plug = clean water, light, food conservation, heat on demand. Greatest gift from Science to humankind = cost effective solar power --- centralized source of energy (no expensive infrastructure required.all benefit) *what really drives scientists CHM151 University of Toronto Scientific Motivation Scientific Motivation ------ TiO2 Solar Cell TiO2 Solar Cell Demo/Electrochemistry in Action Demo/Electrochemistry in Action Sunlight absorbed by dye on TiO 2 --- Note electron transferred to TiO 2 from excited dye TiO 2 solar cells can approach 10% --- major challenge is to prevent degradation (loss of I- /I 3- relay and dye regeneration) TiO2 can be painted on --- high surface coverage S. K. Deb et al. World Conference on Photovoltaic Solar Energy Conversion, Vienna 1998 CHM151 University of Toronto Electrochemistry Basics Electrochemistry Basics 1. Re: Oxidation Numbers Electrons go to strongest electron magnet (atoms with largest electronegativities) <<< DEMO >>> Keeps track of electrons to help balance equations (mass...
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