Lec-39-FinalExamReview-1

Lec-39-FinalExamReview-1 - Lec-29-FinalExamReview-1...

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Lec-29-FinalExamReview-1 12/9/2011 Everything 1 Lec-39: Final Exam - Review 1 Please complete the Course Evaluations End date is December 12 First Principle of Thermodynamics Conservation of energy: energy cannot be created or destroyed. E q w    Energy exchanged by the sy Change in internal energy o stem with surroundings as f the syst heat or wo em rk 2
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Lec-29-FinalExamReview-1 12/9/2011 Everything 2 Volume type of work – P ext constant 0 0 fi V V V w 0 0 V V V w ext i0 00 f if 0 w w PV V w V    3 Interaction of the system with the surroundings: heat q System: gas The temperatures of the system and its surroundings are different. Energy is exchanged between the system and its surroundings through the walls . ( T sys > T surr ): Heat q flows from the system to the surroundings ( q < 0). ( T sys < T surr ): Heat q flows from the surroundings to the system ( q > 0). Heat q has units of energy (J) T sys T surr 4
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Lec-29-FinalExamReview-1 12/9/2011 Everything 3 Enthalpy Changes For any given transformation at constant pressure: (initial) → (final) > 0 the system releases energy to its surroundings 0 exothermic 0 the system absorbs energy from its surroundings 0 endothermic proce proce s ss s f i p H H H H q H   5 Heat Capacity (at constant pressure) specific molar extensive per unit mass per mol p p sp C mn q c T c TT   0 energy has units of temperat J ,, C ure p p p q H C T C T    Heat capacity: heat exchanged by the system per unit change in its temperature under constant external pressure : 0 J heat capacity per unit mass, kg C p s C c m 0 J heat capacity per mol, mol C p p C c n 6
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Lec-29-FinalExamReview-1 12/9/2011 Everything 4 Enthalpy Changes: Physical and Chemical Processes                 -1 22 -1 2 2 2 2 2 H g O g 2H O g 1 H g O g H O g 241.8kJ mol 2 reactio 483.6kJ m n ol reaction 2 1 2 H H H H          Δ H reaction at 25 °C and 1 bar: standard enthalpies of reaction Δ H °         2 0 2 0 H O H O g H (1 bar, 25 C) (1 bar, 25 C 44.0 44.0 O g H O kJ/m kJ/mol ol ) H H  7 Enthalpy Changes: Formation Reactions Δ H f ° Standard molar enthalpies of formation: enthalpies per mol of reaction Δ f of a substance starting from the elements in their stable state at standard conditions (1 bar and 25°C)       -1 1 2 2 2 2 H g O g H O 285.8kJmol f H         2 2 4 2C graphite 2H g C H g 52.26kJmol f H        0 H g H g 0 f H The enthalpy of formation of an element in its standard state at 25°C is zero.
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Lec-39-FinalExamReview-1 - Lec-29-FinalExamReview-1...

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