Chemical Affinity and Heat Reaction of Thermodynamic Systems at Ultra-Low Temperatures

The chemical affinity and reaction heat are two important parameters for studying the properties of the chemical reactions of thermodynamic systems at low temperatures. It is expounded that for a thermodynamic system only containing volume variable work, the two parameters in the reversible isothermal and isobaric process can be calculated through the thermodynamic theory and both of them are zero. These two parameters must be measured by experiment in the irreversible isothermal and isobaric process and their values depend on the irreversibility of the isothermal and isobaric process, but the relationship between them can be discussed by thermodynamic theory. When the temperature is absolute zero, both of these parameters are zero. Some examples given in textbooks and literature are debatable.