Entropy is seen in situations that involve the dispersal of energy from a concentrated state to a less concentrated one, such as a hot pan cooling down, a tire blowing and releasing its air, the rusting of metal or cream mixing with coffee in a mug. These examples follow the definition of entropy, which is a measure of how energy and matter are dispersed within a system.Continue Reading
According to the second law of thermodynamics, energy between a system and its surroundings spreads out towards equilibrium if unobstructed from doing so; entropy changes are determined by how the amount of energy is dispersed and spread. When matter spreads to a greater volume, such as the cream in the coffee cup, the energy content also spreads and increases entropy.
Entropy is not a measure of disorder. The rusting of metal, for example, involves an increase in entropy because iron and oxygen change to a lower energy state, iron oxide, but without any disorder introduced. Systems in an ordered state can contain more energy than their disordered state, so the system becomes disordered as a byproduct of the energy spreading out to reach equilibrium. However, if a neat room is taken as a system and the room is trashed to create disorder, the amount of energy contained in the room is not changed or spread with its surroundings, thus entropy is not changed.Learn more about Physics