Chapter 5 Notes

Chapter 5 Notes - Enthalpy change for a reaction is equal...

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Chapter 5 Thermochemistry The First Law of Thermodynamics Energy is conserved Internal Energy ΔE=E final - E initial Relating E to Heat and Work ΔE= q + w When heat is added to a system or work is done ON a system, its internal energy increases Endothermic and Exothermic Processes Endothermic- absorbs heat Exothermic- loses heat State Functions Value of a state function depends on the present state of system, not on path the system took to reach that state Enthalpy w= -PΔV enthalpy accounts for heat flow in processes occurring at constant pressure when no forms of work are performed other than P-V work H= E+ PV ΔH=q p , change in enthalpy equals heat gained or lost at constant pressure Enthalpies of Reaction ΔH = H products - H reactants Enthalpy is an extensive property
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Unformatted text preview: Enthalpy change for a reaction is equal in magnitude, but opposite in sign, to H for the reverse reaction The enthalpy change for a reaction depends on the state of the reactants and products Chapter 5 Thermochemistry Calorimetry Heat Capacity and Specific Heat Specific heat (s) = q/ (m*T) q= mcT Constant Pressure Calorimetry q soln = -q rxn Bomb Calorimetry Hess Law If a reaction is carried out in a series of steps, H for the overall reaction will equal the sum of the enthalpy changes for the individual steps Enthalpies of Formation H rxn = nH f (products) - mH f (reactants) Foods and Fuels Fuel value of a substance is heat released when 1 g is combusted...
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This note was uploaded on 03/27/2008 for the course CHEM 177 taught by Professor Greenbowe during the Spring '06 term at Iowa State.

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Chapter 5 Notes - Enthalpy change for a reaction is equal...

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