Spontaneity, Entropy, and Free Energy 1 st law of thermodynamics – energy of the universe is constant

Spontaneous Process Occurs without outside interventions Examples: A ball rolls down a hill A nail rusts Heat flows from hot  cold Wood Burns NOT SPEED

Entropy (S) Measure of molecular randomness or disorder Universe is always trying to increase in entropy. Which has the greatest disorder? Solid Liquid Gas Signs for Entropy  S = S final – S initial +  S = -  S = << Spontaneous Nonspontaneous

Spontaneity and # of particles 2 H 2 (g) + O 2 (g)  2 H 2 O (g) Sign for  S = NaCl (s)  Na + (aq) + Cl – (aq) Sign for  S = -,because 3(g)  2(g) +, more particles and free to move

 S surroundings = -  H/T What does the above formula mean? Temperature affects the  S surrounding  S sys  s surr  S universe Spontaneous ? - + ? yes no(reverse is) Yes,  S sys >  S surr Yes,  s surr >  S sys