Entropy is a concept that has been introduced in thermodynamics. Using this value, a measure of energy dissipation is determined. Any system experiences a confrontation that arises between heat and a force field. An increase in temperature leads to a decrease in the degree of orderliness. To determine the measure of disorder, a quantity called entropy is introduced. It characterizes the degree of exchange of energy flows in both closed and open systems.
The change in entropy in isolated circuits occurs in the direction of increase along with an increase in heat. This measure of disorder reaches its maximum value in a state characterized by thermodynamic equilibrium, which is the most chaotic.
If the system is open and at the same time non-equilibrium, then the change in entropy occurs downward. The magnitude of this measure in this embodiment is characterized by the formula. To obtain it, a summation of two quantities is performed:
- the flow of entropy occurring due to the exchange of heat and substances with the environment;
- the magnitude of the change in the indicator of chaotic motion within the system.
Entropy changes occur in any environment where biological, chemical and physical processes occur. This phenomenon is realized at a certain speed. The change in entropy can be a positive value - in this case, an influx of this indicator into the system from the external environment occurs. There are cases when a value indicating a change in entropy is defined with a minus sign. This numerical value indicates the outflow of entropy. The system may be stationary. In this case, the amount of entropy produced is offset by the outflow of this indicator. An example of such a situation is the state of a living organism. It is nonequilibrium, but at the same time stationary. Any organism pumps negative entropy from its environment. The isolation of a measure of disorder from it may even exceed the amount of income.
Entropy production occurs in any complex systems. In the process of evolution, information is exchanged between them. For example, when water evaporates, information about the spatial arrangement of its molecules is lost. There is a process of increasing entropy. If the liquid freezes, the uncertainty in the arrangement of the molecules is reduced. In this case, the entropy is reduced. Cooling a liquid causes a decrease in its internal energy. However, when the temperature reaches a certain value, despite the removal of heat from the water, the temperature of the substance remains unchanged. This means that the transition to crystallization begins. A change in entropy during an isothermal process of this type is accompanied by a decrease in the measure of the randomness of the system.
A practical method to measure the temperature and heat of fusion of a substance is to carry out work, the result of which is the construction of a solidification diagram. In other words, based on the data obtained as a result of the study, we can draw a curve that indicates the dependence of the temperature of the substance on time. In this case, external conditions must be unchanged. It is possible to determine the change in entropy by processing the data of a graphic image of the results of the experiment. On such curves there is always a section in which the line has a horizontal gap. The temperature corresponding to this segment is the solidification temperature.
A change in any substance, accompanied by a transition from a solid to a liquid at its ambient temperature equal to the melting temperature, and vice versa, is attributed to a first-order phase change. In this case, the density of the system, its internal energy, and entropy change.