1.1 Thermodynamics and its method

 

Thermodynamics is the science of the regularities governing processes of energy conversion.

The fundamentals of thermodynamics were laid in the nineteenth century when the development of heat engines necessitated the study of the regularities governing the conversion of heat into work. But later on the method of thermodynamics stepped over the limits of heat engineering and found wide application in many branches of physics, chemistry and of other sciences.

Thermodynamics makes it possible to determine the direction in which various physical and chemical processes may proceed in different systems. As it will be seen, thermodynamics reveals the profound relations between different properties of substance. In principle, this permits, with the data on the heat capacities of a substance available, to use thermodynamic methods in calculating, for instance, the density of this substance, and vice versa.

As distinguished from other branches of physics and chemistry, thermodynamics does not operate with any models of the structure of substance, and is in general not related directly to the notions of the microstructure of substance, which is the strength but also the weakness of thermodynamics.

Thermodynamics itself is incapable of giving any data on the properties of substance. But if some of the data are known, thermodynamic methods permit very interesting and important conclusions to be drawn.

The construction principle of thermodynamics is simple. Thermodynamics is based on two main laws, established by experiment. The first law of thermodynamics characterizes the quantitative side of energy conversion processes, and the second law sets up the qualitative side (direction) of processes in physical systems[1]. Making use of these two fundamental laws and applying the method of strict deduction we can obtain all main conclusions of thermodynamics.

Thermodynamics is applicable to all systems for which its fundamental laws are true. The first law of thermodynamics, as it will be seen, is the quantitative expression of the law of conservation and conversion of energy, and it is of a general nature. As to the second law, it is based on the experience accumulated in observing and studying macro systems within the scope accessible to direct observation.

Given in this chapter below are the necessary primary data, concepts and definitions preceding the treatment of thermodynamics proper.

 

 

 



[1] Neither the first nor the second law of thermodynamics rests upon any assumptions on the structure of substance, and it is precisely this fact that ensures, as it was already mentioned above, the great generality of the methods of thermodynamics.