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In Friday's lecture, Lavelle had on is powerpoint, "In any spontaneous process there is an increase in entropy." Does this mean that in any non-spontaneous process there is a decrease in entropy?
Not necessarily, as we learn later, Gibbs Free Energy or (G) determines the spontaneity of a reaction. It is determined by change in enthalpy, absolute temperature, and entropy: . If (G) is negative, the reaction is spontaneous.
To add to the previous answer, the spontaneity, or Gibbs free energy depends on entropy and enthalpy. Positive entropy and negative enthalpy means the reaction is spontaneous at all temperatures. Positive entropy and enthalpy means the reaction is spontaneous at high temperatures. Negative entropy and enthalpy means the reaction is spontaneous at low temperatures. Negative entropy and positive enthalpy means the reaction is not spontaneous at any temperature.
Spontaneity refers to any reaction that favors products over reactants. Because so much energy is used to make the products, there's always going to be a decrease in free energy (Gibbs free energy). That is why is negative. Entropy must stay positive (or increase) in order to keep negative.
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