| | which is the basis of the accurate determination of the absolute entropy of pure substances from measured heat capacity curves and entropy changes at phase transitions, i.e. by calorimetry.<ref name="Oxtoby8th">Oxtoby, D. W; Gillis, H.P., [[Laurie Butler|Butler, L. J.]] (2015).''Principles of Modern Chemistry'', Brooks Cole. p. 617. {{ISBN|978-1305079113}}</ref> <ref name="MortimerBook"></ref> Introducing a set of internal variables <math>\xi</math> to describe the deviation of a thermodynamic system in physical equilibrium (with the required well-defined uniform pressure ''P'' and temperature ''T'')<ref name="Schmidt-Rohr 14"></ref> from the chemical equilibrium state, one can record the equality | | which is the basis of the accurate determination of the absolute entropy of pure substances from measured heat capacity curves and entropy changes at phase transitions, i.e. by calorimetry.<ref name="Oxtoby8th">Oxtoby, D. W; Gillis, H.P., [[Laurie Butler|Butler, L. J.]] (2015).''Principles of Modern Chemistry'', Brooks Cole. p. 617. {{ISBN|978-1305079113}}</ref> <ref name="MortimerBook"></ref> Introducing a set of internal variables <math>\xi</math> to describe the deviation of a thermodynamic system in physical equilibrium (with the required well-defined uniform pressure ''P'' and temperature ''T'')<ref name="Schmidt-Rohr 14"></ref> from the chemical equilibrium state, one can record the equality |
| | which is the basis of the accurate determination of the absolute entropy of pure substances from measured heat capacity curves and entropy changes at phase transitions, i.e. by calorimetry.[16] [11] Introducing a set of internal variables {\displaystyle \xi }\xi to describe the deviation of a thermodynamic system in physical equilibrium (with the required well-defined uniform pressure P and temperature T)[15] from the chemical equilibrium state, one can record the equality | | which is the basis of the accurate determination of the absolute entropy of pure substances from measured heat capacity curves and entropy changes at phase transitions, i.e. by calorimetry.[16] [11] Introducing a set of internal variables {\displaystyle \xi }\xi to describe the deviation of a thermodynamic system in physical equilibrium (with the required well-defined uniform pressure P and temperature T)[15] from the chemical equilibrium state, one can record the equality |
| − | : <math>\mathrm dS = \frac{\delta Q}{T} - \frac{1}{T} \sum_{j} \, \Xi_{j} \,\delta \xi_j \,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \text {(closed system, actually possible quasistatic irreversible process).}</math> | + | : <math>\mathrm dS = \frac{\delta Q}{T} - \frac{1}{T} \sum_{j} \, \Xi_{j} \,\delta \xi_j \,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \text {(closed system, actually possible quasistatic irreversible process 封闭系统,实际可能的准静态不可逆过程).}</math> |
| | The second term represents work of internal variables that can be perturbed by external influences, but the system cannot perform any positive work via internal variables. This statement introduces the impossibility of the reversion of evolution of the thermodynamic system in time and can be considered as a formulation of the second principle of thermodynamics – the formulation, which is, of course, equivalent to the formulation of the principle in terms of entropy. | | The second term represents work of internal variables that can be perturbed by external influences, but the system cannot perform any positive work via internal variables. This statement introduces the impossibility of the reversion of evolution of the thermodynamic system in time and can be considered as a formulation of the second principle of thermodynamics – the formulation, which is, of course, equivalent to the formulation of the principle in terms of entropy. |
| | The zeroth law of thermodynamics in its usual short statement allows recognition that two bodies in a relation of thermal equilibrium have the same temperature, especially that a test body has the same temperature as a reference thermometric body. For a body in thermal equilibrium with another, there are indefinitely many empirical temperature scales, in general respectively depending on the properties of a particular reference thermometric body. The second law allows a distinguished temperature scale, which defines an absolute, thermodynamic temperature, independent of the properties of any particular reference thermometric body. | | The zeroth law of thermodynamics in its usual short statement allows recognition that two bodies in a relation of thermal equilibrium have the same temperature, especially that a test body has the same temperature as a reference thermometric body. For a body in thermal equilibrium with another, there are indefinitely many empirical temperature scales, in general respectively depending on the properties of a particular reference thermometric body. The second law allows a distinguished temperature scale, which defines an absolute, thermodynamic temperature, independent of the properties of any particular reference thermometric body. |