Lec17 Energy IV - Energy Chemistry and Society IV Chapter 8...

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Energy, Chemistry and Society IV Chapter 8, Sections 8.1-8.3, 8.5 Electrochemistry = Direct generation of electricity by chemical reaction (batteries) Solar Energy = Direct generation of electricity by the absorption of light
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Large-Scale Electrical Power Generation How does the turbine move? Coal combustion - Steam (Heat) Nuclear power - Steam (Heat) Hydroelectric - Water Wind Power - Air Direct generation of electricity from batteries or solar radiation is for smaller scale use.
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Basic Principle of Electrochemistry: Keep reactants separated so that electrons (current) must move through a wire in order for the reaction to occur. Oxidation (at anode): Zn ( s ) Zn 2+ ( aq ) + 2e - Reduction (at cathode): Cu 2+ ( aq ) + 2e - Cu ( s ) “Net” reaction “Half” reactions
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A galvanic cell is a device that converts the energy released in a spontaneous chemical reaction into electrical energy. This is accomplished by the transfer of electrons from one substance to another. Consider a nickel-cadmium (NiCad) battery: Electrons are transferred from cadmium to nickel. Chemical to electrical energy Net reaction: 2Ni +3 ( aq ) + Cd ( s ) 2Ni +2 ( aq ) + Cd +2 ( aq )
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The electron transfer process involves two changes: the cadmium is oxidized , and the nickel is reduced . Each process is expressed as a half-reaction: Oxidation half-reaction: Cd Cd 2+ + 2 e Reduction half-reaction: 2 Ni 3+ + 2 e 2 Ni 2+ Net reaction: 2 Ni 3+ + Cd 2 Ni
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This note was uploaded on 11/20/2011 for the course CHEM 100 taught by Professor Vanleer,m during the Spring '08 term at University of Delaware.

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Lec17 Energy IV - Energy Chemistry and Society IV Chapter 8...

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