Called spontaneous reactions. Spontaneous does not imply anything about time for reaction to occur. Thermodynamics and Kinetics Diamond is thermodynamically favored to convert to graphite, but not kinetically favored. Paper burns a product-favored reaction. Also kinetically favored once reaction is begun.
Spontaneity is related to an increase in randomness.
The potential energy starts out in a few molecules but disperses over many molecules. Entropy of a substance increases with temperature. Increase in molecular complexity generally leads to increase in S. Entropy usually increases when a pure liquid or solid dissolves in a solvent.