1.5 - Second Law of Thermodynamics

entropy (∆S)

measure of randomness or disorder in a system

second law of thermodynamics

all changes either directly or indirectly increase the entropy of the universe

spontaneous reaction

one that, given the necessary activation energy, proceeds without continuous outside assistance

∆S > 0

volume of a gaseous system increases
temperature of a system increases
physical state of system changes from solid to liquid or liquid to gas
fewer moles of reactants form more moles of products

Gibbs free energy (G)

the maximum energy available to do useful work (G = H - T*S)

exergonic

delta G is negative, spontaneous reaction

endergonic

delta G is positive, non-spontaneous reaction