States and Equilibrium Equilibrium:a state of balance (no unbalanced potentials and driving forces Thermodynamic equilibrium requires simultaneously -Thermal equilibrium(constant temperature) -Mechanical equilibrium(constant pressure at a given point;not throughout) -Chemical equilibrium (no chemical reactions) -Phase equilibrium (each phase at equilibrium) sun 20℃ 23C 32C 32C 30C 32C 35C 40°C 32C 32C 42°C 32C cao (a)Before (b)After the equilibrium state of a simple compressible system is completely specified by 2 independent,intensive properties )上泽元通大学 February 28,2019 26 SHANGHAI JIAO TONG UNIVERSITYFebruary 28, 2019 26 States and Equilibrium Equilibrium: a state of balance (no unbalanced potentials and driving forces ) • Thermodynamic equilibrium requires –Thermal equilibrium (constant temperature) –Mechanical equilibrium (constant pressure at a given point; not throughout) –Chemical equilibrium (no chemical reactions) –Phase equilibrium (each phase at equilibrium) the equilibrium state of a simple compressible system is completely specified by 2 independent, intensive properties sun liu cao simultaneously