# State (thermodynamics)

The **state of** a system in thermodynamics is characterized by the specification of all state variables necessary for the delimitation from other states .

State variables include pressure , volume , temperature , amount of substance . These sizes are divided into extensive (quantity-dependent) and intensive (not quantity-dependent).

The individual states are often entered in a phase diagram . Depending on the plot, a single point usually corresponds to a state in the state space , but sometimes all points of a phase line or area also belong to a single state.

## Statistical Physics

In statistical mechanics (statistical thermodynamics) there is the following distinction:

- In the case of the microstate , the individual locations and impulses of all particles are given, so the microstate corresponds to a point in phase space .
- the macrostate is an indication of mean values such as temperature, pressure and density. A macrostate includes all microstates that are compatible with the specified state variables.

### Example coin toss

*KZKKZZKK* is a special microstate.

5x *K* and 3x *Z* is then the macrostate to which microstates belong (the number results from the combinatorics as a permutation of objects of two classes *K* and *Z,* taking into account the sequence).