What is entropy?

Entropy is a concept from thermodynamics and statistical mechanics that quantifies the amount of disorder or randomness in a system. It reflects the number of possible microstates or arrangements that a system can have at a given energy level. As a system evolves towards equilibrium, entropy tends to increase, indicating a natural progression towards more disordered states.

In simple terms, a high entropy state signifies that the system's particles are distributed in a way that is more chaotic and less predictable, while a low entropy state corresponds to a more ordered, organized arrangement. This tendency for systems to move towards higher entropy is foundational to the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease over time.

In contrast, other options reference concepts that are distinct from entropy. For example, measuring energy does not directly equate to assessing disorder but relates more to the capacity to do work. Temperature change pertains to kinetic energy rather than the distribution and arrangement of particles. Lastly, the notion of a specific type of chemical reaction does not capture the broader implications of disorder that entropy encompasses.