Entropy of independent subsystems is sum of their entropies

If a thermodynamic system can be decomposed into several subsystems which are all statistically independent, the total entropy of the system can be calculated as the sum of the entropies of all the subsystems. Mathematically speaking, this is a representation of such a property of entropy known as subadditivity.

Conditions:

1. The subsystems must be (approximately) independent in the statistical sense.

Links:

1. ScienceDirect.

total_entropy

Total entropy of the system as a whole.

Symbol:

S

Latex:

\(S\)

Dimension:

energy/temperature

subsystem_entropy

entropy of the \(i\)-th subsystem.

Symbol:

S[i]

Latex:

\({S}_{i}\)

Dimension:

energy/temperature

law

S = Sum(S[i], i)

Latex:

\[S = \sum_i {S}_{i}\]