Answer: Entropy.
Explanation:
If we recall the laws of thermodynamics, there is a state function called entropy, that is related to the disorder in the system.
Such that, for example, in a gas expansion, we will have an increase in the "disorder" then we will have an increase in the entropy, this happens because we have more volume where the particles can be, then we have a larger number of "microstates" (or microscopic states, which refers to the states of the particles that conform the gas)
Particularly, when we go into statistical thermodynamics, there is something called the "Statistical entropy" that is related to the information theory, where the entropy depends on the number of possible outcomes that some event, like a chemical reaction, can have.
For a larger number of possible outcomes, we will have a larger entropy (we can think of this larger number of possible options as a disorder) and this entropy will be related to the statistical probability of each one of those outcomes.
Where the (most general) equation for the entropy is:
S = Kb*Σpₙ*ln(pₙ)
Where pₙ is the probability for the n-th outcome.
Kb is Boltzman's constant.
