THE Thermodynamics is the area of Physics that studies several phenomena and complex physical systems in which exchanges of heat, transformations of energy and temperature variations. Thermodynamics is governed by fourlaws.entropy, temperature, heat and volume that allow us to describe different systems through variables such as pressure, volume, temperature, heat and entropy.
See too: Calorimetry: a summary of what is most important in this area
Fundamentals of Thermodynamics
Thermodynamics is a statistical description of nature, through it it is possible to conceive the macroscopic behavior of systems that contain many bodies. As this area of study is quite broad, some fundamental concepts will be presented in order to facilitate the understanding of the laws discussed below.
thermodynamic system
Thermodynamic systems are distinguishable regions of their neighborhoods because of some characteristic. These regions can be separated by walls, membranes, among others, for example, it is possible to consider the
gas inside a balloon as a system.the definition of systemclosed, in turn, is a little more restricted. Closed systems are those that do not exchange heat or exercise or receive work of their neighborhoods.
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thermodynamic state
The thermodynamic state concerns a set of variables which can be used to describe the conditions of a system. This enables the reproduction of these conditions by another experimenter, for example, in other words, the state of a system symbolizes its condition, through parameters such as pressure, volume, temperature. When a system undergoes a change of thermodynamic state, we say that it has undergone a transformation.
thermodynamic equilibrium
Thermodynamic equilibrium is the condition in which a system does not show any trends towards change. spontaneous thermodynamic state, that is to say that a system that is in equilibrium thermodynamic does not change its state spontaneously, unless he is influenced by his surroundings.
The concept of thermodynamic equilibrium is also important to understand the idea of reversible transformation and irreversible transformation. Transformationsreversible are those that occur very close to the equilibrium situation, in this sense, a system that is undergoing a reversible transformation quickly returns to equilibrium.
Transformationsirreversible are those in which the equilibrium conditions are less and less accessible, making the whole system changes its characteristics in such a way that it is no longer possible for it to return to the state previous.
Temperature
According to the kinetic theory of gases, the temperature can be understood as the macroscopic manifestation of the kinetic energy of the constituent particles of a thermodynamic system. This temperature, therefore, measures the degree of agitation. Its unit of measure is the kelvin (K).
Lookalso:Gamma rays: radiation that comes from space and is capable of passing through the human body
thermodynamic work
The thermodynamic work is the energy exchange between two thermodynamic systems because of the movement of its borders. For example, when you heat a gas inside a syringe plunger, at a certain point, the pressure exerted by the gas is great enough to push the plunger. This energy, then, in the form of a mechanical energy, is transferred from the gas to the external environment, causing the temperature and internal energy of the gas to decrease.
Laws of Thermodynamics
There are four laws of thermodynamics and each one of them relates to a concept of Thermology, let's check what the laws of Thermodynamics are and what each one of them says:Zero Law of Thermodynamics
The Zero Law of Thermodynamics states that all bodies in contactthermal transfer heat to each other until the balancethermal. The Zero Law of Thermodynamics is usually explained in terms of three bodies: A, B and C.
According to this explanation, bodies A, B and C have been in thermal contact for a long time, so if body A is in thermal equilibrium with the body B, body C will be in thermal equilibrium with bodies A and B, in this case, the temperatures of A, B and C will be equal and there will be no more heat exchanges between they.
"All bodies exchange heat with each other until the condition of thermal equilibrium is reached."
First Law of Thermodynamics
The first law of thermodynamics concerns the conservationinenergy. According to this law, all the energy that is transferred to a body can be stored in the body itself, in this case, being transformed into internal energy. The other portion of energy that is transferred to the body can be transferred to the surroundings in the form of work or in the form of heat.
The formula used to describe the first law of Thermodynamics is shown below, check it out:
"The variation in the internal energy of a thermodynamic system is measured by the difference between the amount of heat absorbed by it and the amount of work done by it, or on it."
Second Law of Thermodynamics
The second law of thermodynamics concerns a physical quantity known as entropy, which is a measure of the number of thermodynamic states of a system, in other words, entropy gives a measure of randomness or the disorganization of a system.
Third Law of Thermodynamics
The third law of thermodynamics concerns the lower limit of temperature: o absolute zero. According to this law, there is no way a body can reach the absolute zero temperature. In addition to this definition, this law also has implications for the performance of thermal machines, which under no conditions can be equal to 100%.
By Rafael Hellerbrock
Physics teacher
