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Unformatted text preview: Chem 130/ WANG / Chapter 5A Fall 2007 UM-SJTU JI 1 Chapter 5.1 to 5.4 Chapter 5.1 to 5.4 Thermochemistry (A) Thermochemistry (A) • Nature of Energy • First Law of Thermodynamics • Enthalpy • Enthalpy of Reaction Thermochemistry s Thermodynamics Thermodynamics – s Thermo = heat s Dynamics = in motion s Thermochemistry Thermochemistry – s The science of heat transfer through chemical reactions. frequently used terms in thermochemistry s System s well-defined part of the universe s Surroundings s Everything else System + surroundings = The The Uiverse Uiverse Everything included!! frequently used terms in thermochemistry s State function s A property of the system s Independent of the path it took to come to the “current state.” s Function only of the “current state” s Examples: State function System final initial Presure: P = P- P Δ final initial Volume: V = V- V Δ final initial Temperature: = T- T T Δ frequently used terms in thermochemistry s Closed system s No mass exchange with surroundings. s Such as a sealed reaction vessel surroundings Closed System mass exchange: No No energy exchange: O.K. O.K. Mass & energy Exchange: Energy only Nothing Practical Examples Practical Examples Open Closed Isolated Chem 130/ WANG / Chapter 5A Fall 2007 UM-SJTU JI 2 frequently used terms in thermochemistry s Energy s Capacity to do WORK or transfer HEAT s Potential Energy (PE) s energy “stored “ s based on static position and force s Between “masses” = gravitational PE s Between“charges” = electrostatic PE s No motion involved frequently used terms in thermochemistry s Chemical Energy s A form of Potential Energy (PE) s Mostly based on “charge” interactions between / among electrons & nucleus. frequently used terms in thermochemistry s Kinetic Energy (KE) s Energy involved in motion s Work (w) s motion of an object against an opposing force s HEAT (q) s random molecular motions s Also called “thermal energy” frequently used terms in...
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