Ch. 20: Entropy and Free Energy. Thermodynamics: the science of energy transfer Objective: To learn how chemists predict when reactions will be product-favored vs. when they will be reactant-favored . Section 20.1. Ø Thermodynamics tells us NOTHING about the rate of reaction.
ØEntropy usually increases when a pure liquid or solid dissolves in a solvent.
Entropy increases when a dissolved gas escapes from a solution
Can also relate surroundings to the system!
= - DHsystem / T
= DHsystem - TDSsystem
DGs are additive!
If not at standard conditions,
DG = DGo + RT ln Q
(Equilibrium is characterized by the inability to do work.)
At equilibrium, Q = K and DG = O
Therefore, substituting into previous equation gives 0 = DGo + RT ln K and
DGo = - RT ln K(can use Kp or Kc)
2020.5 Thermodynamics and Time