Chapter 19 – Free Energy And Thermodynamics

Review Chemistry I material from Chapter 10 Thermochemistry, especially the first law of thermodynamics and change in enthalpy (DH)

DEFINE:

• Spontaneous as a thermodynamic concept
• Entropy (S)
• Second Law of Thermodynamics in words and in symbols
• Standard conditions for thermodynamics
• Third Law of Thermodynamics
• Gibb’s Free Energy (ΔG) in words and mathematically (ΔG=ΔH-TΔS)
• Reversible and irreversible reactions

DO:

• Determine if a process is spontaneous or nonspontaneous
• Explain entropy (S) based on the number of possible microstates

Predict changes in entropy (sign of ΔS) for common processes like phase changes.

• State and use the proper units for entropy
• Explain the dependence of standard molar entropy (S°) on physical state, molar mass, atomic arrangement, and molecular complexity
• Predict spontaneity of a reaction based on the sign of ΔG (and considering the role of the signs of ΔH and ΔS)

CALCULATE:

• Standard entropy change for a chemical reaction or physical change (ΔS°_rxn)
• State and apply the relationship ΔS_universe = ΔS_system + ΔS_surroundings
• The entropy change of the surroundings (ΔS_surroundings) from the enthalpy change of the system (ΔH_system) and the temperature
• ΔG from ΔH, ΔS and T (and ΔG°_reaction from ΔH°, ΔS° and T)
• The temperature (T*) where ΔG changes from spontaneous to nonspontaneous
• ΔG° from free energy of formation (ΔG°_f ) of the reactants and products
• ΔG° given ΔG°’s for each step of a multistep process

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