Thermodynamics is ... Definition, laws, applications and processes

What is thermodynamics? This is a section of physics that deals with the study of the properties of macroscopic systems. At the same time, the methods of energy conversion and the methods of its transmission also fall under the study. Thermodynamics is a branch of physics that studies the processes taking place in systems and their states. About what else falls into the list of things studied by her, we'll talk today.

Definition

In the picture below you can see an example of a thermogram obtained in the study of a jug with hot water.

Thermodynamics is a science that relies on generalized facts obtained by experience. Processes occurring in thermodynamic systems are described by using macroscopic quantities. Their list includes such parameters as concentration, pressure, temperature and the like. It is clear that they can not be applied to individual molecules, but are reduced to describing the system in its general form (in contrast to those used in electrodynamics, for example).

Thermodynamics is a branch of physics that also has its own laws. They, like the rest, are of a general nature. Specific details of the structure of a given substance will not have a significant effect on the nature of the laws. That is why it is said that this section of physics is one of the most applicable (or rather, successfully applied) in science and technology.

Application

You can list examples for a very long time. For example, many solutions based on thermodynamic laws can be found in the field of thermal engineering or electric power engineering. What about the description and understanding of chemical reactions, phase transitions, transport phenomena. In a way, thermodynamics "cooperates" with quantum dynamics. The sphere of their contact is a description of the phenomenon of black holes.

Laws

The picture above shows the essence of one of the thermodynamic processes - convection. The warm layers of matter rise to the top, the cold layers - go down.

The alternative name of laws, which, by the way, is used not as an example more often, it is the beginning of thermodynamics. To date, they know three (plus one "zero", or "general"). But before we talk about what each of the laws implies, we will try to answer the question of what the beginnings of thermodynamics are.

They are a collection of certain postulates that form the basis for understanding the processes occurring in macrosystems. The provisions of the beginning of thermodynamics were established empirically as the series of experiments and scientific studies were carried out. Thus, there are certain proofs that allow us to take the postulates into service without any doubt about their accuracy.

Some people ask themselves why thermodynamics needs these very laws. Well, we can say that the need for their use is due to the fact that in this section of physics the macroscopic parameters are described in a general way, without any hint of considering their microscopic nature or features of the same plan. This is not the sphere of thermodynamics, but of statistical physics, to be more specific. Another important thing is the fact that the onset of thermodynamics does not depend on each other. That is, one of the second can not be deduced.

Application

The application of thermodynamics, as was said earlier, goes in many directions. By the way, one of its principles is taken as a basis, which is otherwise interpreted in the form of the law of conservation of energy. Thermodynamic solutions and postulates are successfully implemented in such industries as energy industry, biomedicine, chemistry. In biological energy, the law of conservation of energy and the law of probability and direction of the thermodynamic process are universally used. Along with this, three most common concepts are used there, on which all work and its description are based. This is a thermodynamic system, process and phase of the process.

Processes

The processes in thermodynamics have a different degree of complexity. There are seven of them. In general, the process in this case should be understood as nothing more than a change in the macroscopic state into which the system was introduced earlier. It should be understood that the difference between the conditional initial state and the final result can be negligible.

If the difference is infinitesimal, then the process that has occurred can be called elementary. If we discuss processes, then we will have to resort to mentioning additional terms. One of them is the "working body". A working body is a system in which one thermal process takes place or several.

Conditionally the processes are divided into nonequilibrium and equilibrium. In the case of the latter, all the states through which the thermodynamic system has to go through are, respectively, nonequilibrium. Often, the change in states occurs in such cases at a rapid pace. But the equilibrium processes are close to quasistatic. In them, the changes are much slower.

Thermal processes occurring in thermodynamic systems can be either reversible or irreversible. In order to understand the essence, we split in our representation the sequence of actions at certain intervals. If we can do the same process in the opposite direction with the same "intermediate stations", then it can be called reversible. Otherwise, it will not work.