Entropy

Entropy is the property of a working substance that increases or decreases according to the heat supplied or removed in a reversible manner. It is a measure of the disorder or randomness of a system. In thermodynamics, entropy is denoted by the symbol "S."

Explanation:

Entropy is a fundamental concept in thermodynamics that helps us understand the behavior of energy and heat transfer in a system. It is related to the second law of thermodynamics, which states that the entropy of an isolated system always increases over time.

When heat is supplied to a substance, the energy is transferred to the particles of the substance, increasing their kinetic energy and causing them to move more randomly. This randomness or disorder is reflected in the increase in entropy.

On the other hand, when heat is removed from a substance, the energy is taken away from the particles, reducing their kinetic energy and causing them to become more ordered. This decrease in randomness is reflected in the decrease in entropy.

Entropy can also be understood as a measure of the number of ways in which the energy of a system can be distributed among its particles. A highly ordered system has low entropy, while a highly disordered system has high entropy.

In a reversible process, the heat transfer occurs in such a way that the system can be returned to its initial state without any net change in entropy. Reversible processes are idealized and do not occur in practice, but they serve as a useful concept for understanding the behavior of real processes.

Entropy is a state function, meaning that its value depends only on the state of the system and not on the path taken to reach that state. It can be calculated using thermodynamic relations and equations, such as the Clausius inequality and the Gibbs equation.

In summary, the property of a working substance that increases or decreases according to the heat supplied or removed in a reversible manner is called entropy. It is a measure of the disorder or randomness of a system and plays a crucial role in understanding thermodynamic processes and the second law of thermodynamics.