3/11/2023 0 Comments Example of entropy![]() ![]() The entropies of solid elements are strongly influenced by the type of atom packing in the solid. The entropies of the diatomic and polyatomic molecules show the additional effects of rotational quantum levels. For the noble gases, this is a direct reflection of the principle that translational quantum states are more closely packed in heavier molecules, allowing them to be occupied. It is apparent that entropies generally increase with molecular weight. ![]() Entropy, however, measures not energy itself, but its dispersal among the various quantum states available to accept it, and these exist even in pure elements. Scientists conventionally set the energies of formation of elements in their standard states to zero. This is the basis of an alternative (and more fundamental) definition of entropy: With more available microstates, the entropy of a system increases. In contrast to the macrostate, which characterizes plainly observable average quantities (temperature, for example), a microstate specifies all molecular details about the system, including the position and velocity of every molecule. For a given set of macroscopic variables, the entropy measures the degree to which the probability of the system is spread out over different possible microstates. The interpretation of entropy is the measure of uncertainty, which remains about a system after its observable macroscopic properties, such as temperature, pressure, and volume, have been taken into account. Thermodynamic entropy has the dimension of energy divided by temperature, which has a unit of joules per kelvin (J/K) in the International System of Units. As a result, entropy (denoted by S) is an expression of disorder or randomness. These processes reduce the state of order of the initial systems. ![]() It determines that thermal energy always flows spontaneously from regions of higher temperature to regions of lower temperature, in the form of heat. Therefore, entropy is also a measure of the tendency of a process, such as a chemical reaction, to be entropically favored or to proceed in a particular direction. In classical thermodynamics, the second law of thermodynamics states that the entropy of an isolated system always increases or remains constant. Meissner effect assumption of molecular disorder generation of Joule heat irreversible thermodynamic process law of entropy increase persistent current phase transition reversible thermodynamic process superconducting transition.Entropy of the Playroom: Andrew Vanden Heuvel explores the concept of entropy while cleaning the playroom. The success of the conventional theory of superconductivity forces us to consider the validity of belief in the law of entropy increase. The persistent current annihilates after the transition into the normal state with the generation of Joule heat and reappears during the return to the superconducting state according to this theory and contrary to the law of entropy increase. This change has resulted to the internal inconsistency of the conventional theory of superconductivity, which is created within the framework of reversible thermodynamics, but predicts Joule heating. Belief in the law of entropy increase forced physicists to change their understanding of the superconducting transition, which is considered a phase transition after 1933. However, if this transition is irreversible, then the Meissner effect discovered in 1933 is experimental evidence of a process reverse to the irreversible process. Therefore, this transition was considered as an irreversible thermodynamic process before 1933. The persistent current, an undamped electric current observed in a superconductor, annihilates after the transition into the normal state. The annihilation of an electric current in normal metal with the generation of Joule heat because of a non-zero resistance is a well-known example of an irreversible process. ![]() The law of entropy increase postulates the existence of irreversible processes in physics: the total entropy of an isolated system can increase, but cannot decrease. ![]()
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