SLIDE 1
Heat transfer
Heat transfer, q, can be measured through calorimetry.
Load bomb
Measure Tinit
Ignite
Measure Tfinal
Constant Volume
CEM 484 Chemical Thermodynamics 2
battery
Chemical Thermodynamics Heat transfer battery Heat transfer, q, can - - PowerPoint PPT Presentation
Chemical Thermodynamics Heat transfer battery Heat transfer, q, can - - PowerPoint PPT Presentation
Chemical Thermodynamics Heat transfer battery Heat transfer, q, can be measured through calorimetry. Load bomb Measure T init Ignite Measure T final Constant Volume Chemical Thermodynamics CEM 484 2 Heat
SLIDE 2
SLIDE 3
Heat transfer
However, most chemistry is performed at constant pressure.
Introduce enthalpy, H
CEM 484 Chemical Thermodynamics 3
SLIDE 4
Heat transfer
Enthalpy is a state function
Evaluate in a similar manner as internal energy U.
CEM 484 Chemical Thermodynamics 4
SLIDE 5
Partial derivative
Certain partial derivatives in DU and DH are not tabulated
To evaluate we need more information; 2nd law, G and A
CEM 484 Chemical Thermodynamics 5
SLIDE 6
Spontaneous Process
Isothermal expansion of an ideal gas
CEM 484 Chemical Thermodynamics 6
Pext Pext
SLIDE 7
Spontaneous Process
2nd Law and entropy
Differential form
CEM 484 Chemical Thermodynamics 7
SLIDE 8
Entropy
Internal energy and entropy
Differential form
CEM 484 Chemical Thermodynamics 8
SLIDE 9
Enthalpy and Entropy
Enthalpy and entropy
To determine whether process is allowed need to know entropy change of universe
CEM 484 Chemical Thermodynamics 9
SLIDE 10
Gibbs Free energy
Gibbs free energy, G
Need to restrict to constant pressure
CEM 484 Chemical Thermodynamics 10
SLIDE 11
Helmholtz Free energy
Helmholtz free energy, A
Need to restrict to constant volume
CEM 484 Chemical Thermodynamics 11