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  2. Entropy - Wikipedia

    en.wikipedia.org/wiki/Entropy

    Since an entropy is a state function, the entropy change of the system for an irreversible path is the same as for a reversible path between the same two states. [22] However, the heat transferred to or from the surroundings is different as well as its entropy change. We can calculate the change of entropy only by integrating the above formula.

  3. Introduction to entropy - Wikipedia

    en.wikipedia.org/wiki/Introduction_to_entropy

    The entropy of the surrounding room decreases less than the entropy of the ice and water increases: the room temperature of 298 K is larger than 273 K and therefore the ratio, (entropy change), of ⁠ δQ / 298 K ⁠ for the surroundings is smaller than the ratio (entropy change), of ⁠ δQ / 273 K ⁠ for the ice and water system. This is ...

  4. Clausius theorem - Wikipedia

    en.wikipedia.org/wiki/Clausius_theorem

    where is the total entropy change in the external thermal reservoirs (surroundings), is an infinitesimal amount of heat that is taken from the reservoirs and absorbed by the system (> if heat from the reservoirs is absorbed by the system, and < 0 if heat is leaving from the system to the reservoirs) and is the common temperature of the ...

  5. Gibbs–Helmholtz equation - Wikipedia

    en.wikipedia.org/wiki/Gibbs–Helmholtz_equation

    The definition of the Gibbs function is = + where H is the enthalpy defined by: = +. Taking differentials of each definition to find dH and dG, then using the fundamental thermodynamic relation (always true for reversible or irreversible processes): = where S is the entropy, V is volume, (minus sign due to reversibility, in which dU = 0: work other than pressure-volume may be done and is equal ...

  6. Thermodynamic equations - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_equations

    Entropy cannot be measured directly. The change in entropy with respect to pressure at a constant temperature is the same as the negative change in specific volume with respect to temperature at a constant pressure, for a simple compressible system. Maxwell relations in thermodynamics are often used to derive thermodynamic relations. [2]

  7. Second law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Second_law_of_thermodynamics

    This is possible provided the total entropy change of the system plus the surroundings is positive as required by the second law: ΔS tot = ΔS + ΔS R > 0. For the three examples given above: 1) Heat can be transferred from a region of lower temperature to a higher temperature in a refrigerator or in a heat pump. These machines must provide ...

  8. Entropy (statistical thermodynamics) - Wikipedia

    en.wikipedia.org/wiki/Entropy_(statistical...

    Entropy changes for systems in a canonical state A system with a well-defined temperature, i.e., one in thermal equilibrium with a thermal reservoir, has a probability of being in a microstate i given by Boltzmann's distribution .

  9. Trouton's rule - Wikipedia

    en.wikipedia.org/wiki/Trouton's_rule

    Trouton’s rule can be explained by using Boltzmann's definition of entropy to the relative change in free volume (that is, space available for movement) between the liquid and vapour phases. [ 2 ] [ 3 ] It is valid for many liquids; for instance, the entropy of vaporization of toluene is 87.30 J/(K·mol), that of benzene is 89.45 J/(K·mol ...