tu95_bear
ENTROPY
A quantity introduced in the first place to facilitate the calculation, and to give clear expressions to the results of thermodynamics. Changes of entropy can be calculated only for a reversible process, and may then be defined as the ratio of the amount of heat taken up to the absolute temperature at which the heat is absorbed. Entropy changes for actual irreversible processes are calculated by postulating equivalent theoretical reversible changes. The entropy of a system is a measure of its degree of disorder. The total entropy of any isolated system can never decrease in any change; it must either increase (irreversible process) or remain constant (reversible process). The total entropy of the Universe therefore is increasing, tending towards a maximum, corresponding to complete disorder of the particles in it (assuming that it may be regarded as an isolated system.) (Pamela Zoline)
ENTROPY
A quantity introduced in the first place to facilitate the calculation, and to give clear expressions to the results of thermodynamics. Changes of entropy can be calculated only for a reversible process, and may then be defined as the ratio of the amount of heat taken up to the absolute temperature at which the heat is absorbed. Entropy changes for actual irreversible processes are calculated by postulating equivalent theoretical reversible changes. The entropy of a system is a measure of its degree of disorder. The total entropy of any isolated system can never decrease in any change; it must either increase (irreversible process) or remain constant (reversible process). The total entropy of the Universe therefore is increasing, tending towards a maximum, corresponding to complete disorder of the particles in it (assuming that it may be regarded as an isolated system.) (Pamela Zoline)