Fundamentals of thermodynamics: basic concepts and laws. (2023)

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Fundamentals of thermodynamics: basic concepts and laws. (1)

Fundamentals of thermodynamics:Thermodynamics deals with the concepts of heat and temperature and the interaction between heat and other types of energy. In general, thermodynamics deals with the movement of energy from one place to another and from one form to another. We discuss the basics of thermodynamics along with its laws in this article.

The word thermodynamics was coined by William Thomson in 1749. The four laws of thermodynamics govern and accurately describe the behavior of these quantities. Please read this article carefully to get a complete understanding of the basics of thermodynamics.

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What is thermodynamics?

Thermodynamics is a discipline of physics that studies heat, work, and temperature and their relationships with energy, radiation, and the physical properties of matter. it should be noted thatthermodynamicsit is a macroscopic science. This means that it is the mass system, not the molecular structure of matter.

Discuss how heat energy is converted to or from other forms of energy and how this process affects matter. Thermal energy is the energy obtained from heat. The movement of microscopic particles inside an object generates heat, and the faster these particles move, the more heat is generated. Scroll down to learn more about the fundamentals of thermodynamics.

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Basic notions of thermodynamics

Thermodynamics is coupled with its own terminology. A thorough knowledge of the fundamentals of thermodynamics lays the foundation for a solid understanding of the various topics covered in thermodynamics and avoids potential confusion.

Thermodynamic Systems

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A thermodynamic system is a specific piece of matter with a definite boundary on which we focus our attention. The system boundary can be real or imaginary, fixed or deformable.

types of systems

Systems are classified into three types:

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1. Isolated system:An isolated system is unable to exchange energy or mass with its surroundings. The universe is seen as an isolated system.
2. Closed system:Energy transfer takes place across the closed system boundary, but mass transfer does not. Closed systems include coolers and gas compression in piston and cylinder assemblies.
3. Open system:In an open system, both mass and energy can move between the system and its surroundings. An open system is illustrated with a steam turbine.

Interactions of thermodynamic systems:

systems artmass flowWorkWarm
isolated system
open system
system closed
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An environment is anything outside of the system that has a direct impact on the behavior of the system.


A boundary is a closed surface that surrounds a system and allows energy or mass to enter or leave the system. The boundaries of a system can be fixed or flexible. The limit is mathematically thin, with no mass or volume.

thermodynamic process

Athermodynamic process It occurs when there is an energetic change within a system that is correlated with fluctuations in pressure, volume, and internal energy.

There are four types of thermodynamic processes, each with its own characteristics, and they are:

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1. Adiabatic process:A process in which no heat is transferred into or out of the system.
2. Isochoric process:A mechanism where the volume does not change and the system does not work.
3. Isobaric process:A process in which there is no pressure variation.
4. Isothermal process:A mechanism in which there is no temperature variation.

Keep reading:heat and thermodynamics

thermodynamic equilibrium

All properties of a system have constant values ​​in any state. Therefore, if you change the value of an attribute, the state of the system will change. When a system in equilibrium is isolated from its surroundings, there is no change in the value of its attributes.

  • If the temperature remains constant throughout the system, we say that it is inthermal balance.
  • We believe that the system is inmechanical scaleif there are no pressure fluctuations in any part of the system.
  • When the chemical composition of a system does not change with time, it is said to be "in."chemical balance.
  • In a biphasic systemphase equilibriumoccurs when the mass of each phase approaches an equilibrium level.

When a thermodynamic system is in chemical, mechanical, and thermal equilibrium and the relevant parameters no longer change with time, it is said to be in thermodynamic equilibrium.

thermodynamic properties

Thermodynamic properties are defined as system properties that can describe the state of the system. Thermodynamic properties can be extensive or intense.

1. Intense properties

Intensive properties are those that are independent of the size (mass) of a system. They do not complement each other. Example: temperature, pressure and density

2. Comprehensive features

Extensive properties are those that depend on the size of the system, such as mass, volume, and total energy U. They are additive in nature.

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  • In general, uppercase letters represent extensive properties (except mass m), while lowercase letters represent intensive properties (except pressure P, temperature T).
  • Extensive properties are those with numerous attributes per unit mass, such as B. specific volume (v=V/m).

Laws of Thermodynamics

The fundamental physical quantities such as energy, temperature, and entropy that describe thermodynamic systems in thermal equilibrium are described under the thermodynamic laws. These thermodynamic principles represent how these quantities react under different conditions.

The following are the four laws of thermodynamics:

1.Zero law of thermodynamics:When two systems are in thermal equilibrium with a third system, the first two systems are also in thermal equilibrium with each other. This property makes it useful to use thermometers as a "third system" and to create a temperature scale.
2.First Law of Thermodynamics:The first law of thermodynamics is often referred to as the law of conservation of energy. The difference between the heat transferred to the system from its surroundings and the work done by the system on its surroundings corresponds to the change in the internal energy of a system.
3.Second law of thermodynamics:Heat does not move spontaneously from a colder area to a warmer area, and heat at a given temperature cannot be completely converted to work. As a result, the entropy of a closed system, or heat energy per unit of temperature, increases with time and eventually reaches a maximum value. Therefore, all closed systems move toward an equilibrium state with maximum entropy and no energy available to do useful work.
4.Third law of thermodynamics:As the temperature approaches absolute zero, the entropy of a perfect crystal of an element in its most stable state tends to zero. This makes it possible to establish an absolute entropy scale, which, from a statistical point of view, indicates the degree of randomness or disorder in a system.

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Fundamentals of Thermodynamic Potentials

Thermodynamic potentials are quantitative measures of the stored energy of a system. Potentials measure the energy fluctuations in a system as it changes from its initial state to its final state. Depending on system limitations, such as temperature and pressure, different potentials are used.

Below are some examples of thermodynamic potentials and associated formulas:

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inner energyΔU = λ − PΔV
Helmholtz free energyF = U - TS
enthalpyH = U + PV
gibbs free energyG = U + VP – TS

Applications of thermodynamics in everyday life.

The use of thermodynamics is everywhere, whether we are sitting in an air-conditioned room or driving any vehicle. Some of these apps are listed below:

  • The second law of thermodynamics governs the operation of various modes of transportation, such as planes, trucks, and ships.
  • All three forms of heat transfer work with the help of thermodynamics. Radiators, heaters, and coolers use heat transfer concepts.
  • Thermodynamics is used in the study of different types of power plants, including nuclear and thermal power plants.

stay tunedembibe.comfor a better understanding of other terms.


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