Notes:
A： Figure 1 is from the authoritative book "The Properties of Gases and Liquids", and the enthalpy change H1 is calculated from the equation of state. From Figure 1A, it can be seen that the accuracy of the state equation is high, but the deviation rate of enthalpy change derived is large. The theoretical basis for the derivation is the differential equation of the second law of thermodynamics.
B， Plot the deviation rate of the state equation (
What is the property Z? What do you mean by “deviation rate”? Thermodynamic properties are usually time-independent.
So what? You compare predictions of rather simple equations of state. The deviations from the experimental values show that these equations are too simple. If you used a reference equation of state, you would get better results.
IAPWS95 uses the second law of thermodynamics (η=1-T1/T2) to calculate the specific heat of water vapor, with theoretical and experimental deviations of 5-15%.
NOTES：
1. The figure above is IAPWS95's calculation of the specific heat of water under high pressure and the experimental deviation rate of 5-15%.
2, the proportion of specific heat determined by the second law of thermodynamics is not large, and the actual deviation rate of the second law of thermodynamics is much larger than 5-15%.
3, at high pressure, the second law of thermodynamics does not hold, and it does not hold at low pressure. The reason "η=1-T1/T2" includes only the temperature (molecular kinetic energy) and does not take into account the potential energy of the molecular interaction.
4，Scientists have long known that using the second law of thermodynamics (η=1-T1/T2) to calculate the thermal properties of working media does not agree with experiments. They favour and protect the second law of thermodynamics, damaging the reputation of the scientific community.
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