Condensation arises when a vapor or gas turns into a liquid state after encountering a surface, usually cold, which lowers its temperature. In the phase change there is a percentage of energy called latent heat.
Internal energy is a concept used in the field of Physics that allows us to identify, within a system and from the disordered and random movement of molecules, a reflection (considered on a macroscopic scale) of energy .
The theory conceives it as the sum of both the internal kinetic energy and the internal potential energy . In this context, the intramolecular potential energy associated with the bond energy , the intermolecular potential energy and the kinetic energy of atoms or molecules involved in the system in question are added.
It cannot be overlooked that, according to guidelines specific to the field of thermodynamics , in every closed system it is found that, in terms of internal energy , its total variation is the same as the figure obtained by adding the quantities. of energy that reach the system in work and heat mode. It must be clarified that, in any case, it is extremely difficult to establish, in most systems, what the complete or absolute internal energy is.
Internal energy characteristics
When the internal energy of a given system is analyzed, various characteristics are revealed. It is conditioned or determined, for example, by the number of massive particles, volume and entropy .
In order to determine what the internal energy of a system is, in a certain state, it is necessary to take a standard state as a reference with the objective of, from that starting point, adding the energy transfers at a macroscopic level that occur as the state is changing. There is also a formula developed from a microscopic perspective of a non-relativistic essence that proposes distinguishing between microscopic kinetic energy (studying movements of atomic nuclei, molecules, electrons, atoms, etc.) and microscopic potential energy (adding variables of physical force fields, bonds of particles and deformation energy associated with solids).
To segment variables taking into account the extensive and intensive properties , the internal energy must be included in the first of the sets since it depends on the amount of substance involved, the mass and the size of the system .
The dynamics of golf invites us to find out, for example, whether the system reaches a greater internal energy before or after the club hits the ball.
Functions and properties
By collecting data and deepening knowledge about the particularities , properties and functions of internal energy , the idea of a state function gains notoriety, to indicate a specific case. In this sense, it is important to emphasize how internal energy admits variations according to possible exchanges of work and heat driven by changes in the volume , temperature or pressure of the system or matter .
We must look, in this framework, towards the principle of conservation of energy (also known as the first law of thermodynamics ). This postulates that a closed system is capable of exchanging energy with the environment under the modalities of heat or work , thus achieving an accumulation of internal energy . In the aforementioned closed system , the increase in internal energy ends up being equivalent to the heat that is supplied to the system, subtracting the work done by said system.
In isolated adiabatic processes , meanwhile, it is determined that the increase experienced in terms of internal energy only arises as a result of the net work that the system has done.
The first of the principles that make up the laws of thermodynamics refers to the conservation of energy and presents heat as essential to compensate for the differences between internal energy and work.
Examples of internal energy
In everyday life, numerous examples arise that allow us to appreciate what and how internal energy is, in practice.
If on a winter day, as a result of the prevailing low temperatures, we want to increase the internal energy in the area of the hands in order to prevent them from getting cold, to describe a frequent action, we must do the work of rubbing them together. Taking advantage of this allusion, space can be given to the phenomenon of thermal conduction (one of the processes that make the transfer or transmission of heat possible), achieved thanks to exchanges of internal energy .
In an inelastic collision , as the collision of one vehicle against another (or against any other obstacle) is classified, kinetic energy cannot be conserved. As a consequence of this, an increase in temperature and some kind of deformation are usually noticed. The dissipation of energy responds in this case to the fact that the increase in internal energy and the work linked to the deformations produced in the elements involved are linked to the kinetic energy that they had prior to the moment of the collision .
If a superheated vapor (that is, a vapor brought to a thermal level higher than the vaporization point) cools a little (thus losing a certain percentage of internal energy ), the temperature drops but no change in the state of the vapor is recorded. gas to a mixture based on liquid and saturated vapor .
Another interesting issue arises based on a chemical reaction , which involves an alteration in both the atomic and molecular structure and gives rise to a variation in the latent or chemical internal energy .