CHEM 1AA3 Lecture Notes - Lecture 13: Boltzmann Equation, Boltzmann Constant, Thermodynamics

• School: McMaster University
• Department: Chemistry
• Course: CHEM 1AA3
• Professor: David Brock

Document Summary

Chem 1a03 lecture 13 entropy and free energy. Although many exothermic reactions are spontaneous, there is not a direct correlation between h and spontaneity. Example: rust on a car is spontaneous adds to entropy of universe. S = k ln(w) w = # of microstate", k = boltzmann constant. The greater number of configurations (or microstates) consistent with macrostate , the greater the entropy of the system. S gas expansion or mixing causes an increase in entropy. S throughout phase changes: in decreasing order: vapor > liquid > solid. Dissolution: entropy of a solution > (entropy of solvent + entropy of solute) Third law of thermodynamics: the entropy of a pure, perfect crystal at 0k is zero. All spontaneous processes result in an increase in the entropy of the universe. Even if a reaction is exothermic, if the n < 0, then work is done on the system srxn = negative.