ABSTRACT
The thermodynamic state of a system is defined by the values of some parameters. Most often in chemistry and biochemistry, the thermodynamic state of a system is defined by four measurable parameters called “state variables”. A property is to be extensive when it is additive. It is said to be intensive when it is not additive. An extensive property is one in which the value of the property changes according to the amount of the material which is present. A system is in thermodynamic equilibrium when the values of the variables characterising the system do not change with time. The thermodynamic equilibrium entails that thermal, mechanical and chemical equilibria are simultaneously reached. This means that the temperature, pressure and concentrations must be identical in all the parts of the system.
