Which law of thermodynamics is closely associated with the concept of entropy?

The second law of thermodynamics is fundamentally linked to the concept of entropy. This law states that in an isolated system, the total entropy can never decrease over time; it either increases or remains constant. Entropy is often understood as a measure of disorder or randomness within a system, and the second law suggests that natural processes tend to move toward a state of maximum disorder.

For example, when heat flows from a hot object to a cold one, the overall entropy of the combined system increases. This aligns with the notion that energy transformations are not 100% efficient, leading to an increase in entropy in the surrounding environment.

The other laws of thermodynamics have different focuses: the zeroth law establishes thermal equilibrium, the first law deals with the conservation of energy, and the third law addresses the behavior of systems as they approach absolute zero temperature. None of these directly encompasses the concept of entropy in the way that the second law does.