I.8 Thermodynamic equilibrium

A system is in thermodynamic equilibrium if its thermodynamic variables (P, V, T, etc.) are constant over time and if there is no exchange between this system and its external environment as well as between the different parts of the system. system. Thermodynamic equilibrium includes both mechanical equilibrium, thermal equilibrium and chemical equilibrium. A system is in mechanical equilibrium when there are no uncompensated forces, both within the system and between the system and the external environment. A system is in thermal equilibrium when the temperature is the same at all its points and is also the same as that of the external environment. A system is in chemical equilibrium when it is not the site of a chemical reaction causing a modification of its internal structure. Noticed The systems studied are assumed to be at rest, that is to say, no overall movement, neither translation nor rotation. The gravitational potential energy of the system is assumed to be constant.