Thermodynamics: Definition, Equation, Formula, Laws & Applications
Thermodynamics is concerned with heat and temperature concepts, as well as the interaction of heat and other types of energy. The four laws of thermodynamics govern and quantitatively describe the behaviour of these quantities. The word thermodynamics was coined in 1749 by William Thomson.
Thermodynamics is a branch of physics that studies heat, work, and temperature and their relationships with energy, radiation, and the physical properties of matter.
On that note, let’s learn about all the basic concepts of thermodynamics along with the application of thermodynamics in detail.
Basic Concepts of Thermodynamics – Thermodynamic Terms
Thermodynamics is coupled with its own vocabulary. A solid comprehension of the fundamental concepts creates the foundation for a solid understanding of the various topics presented in thermodynamics, avoiding potential misunderstandings.
A thermodynamic system is a specific portion of matter with a defined boundary on which we focus our attention. The system boundary can be physical or fictitious, fixed or malleable.
There are three types of systems which are isolated system, closed system and open system.
Anything external to the system that directly affects how it behaves is said to be its surroundings.
A thermodynamic process occurs when there is an energetic shift within a system that is connected with changes in pressure, volume, and internal energy.
There are four types of thermodynamic processes that have their unique properties, and they are the Adiabatic Process, Isobaric Process and Isothermal Process.
All properties of a system have fixed values at any given state. As a result, the system's state changes if the value of even one attribute changes. When an equilibrium system is isolated from its surroundings, no changes in the value of its attributes occur.
If a thermodynamic system is in chemical equilibrium, mechanical equilibrium, and thermal equilibrium, and the relevant parameters no longer vary with time, it is said to be in thermodynamic equilibrium.
Thermodynamic potentials are quantifiable measures of a system's stored energy. Potentials assess the energy changes in a system as it transitions from its starting to final state. Depending on the system conditions, such as temperature and pressure, different potentials are used.
Different forms of thermodynamic potentials along with their formula are listed below:
Helmholtz free energy:
F = U – TS
H = U + PV
Gibbs Free Energy:
G = U + PV – TS
Laws of Thermodynamics
The fundamental physical quantities such as energy, temperature, and entropy that describe thermodynamic systems at thermal equilibrium are defined by thermodynamic laws. These thermodynamic laws depict how these quantities respond under various settings. Let’s learn about the four important laws of thermodynamics.
Zeroth Law of Thermodynamics
According to the Zeroth Law of Thermodynamics, if two bodies are individually in equilibrium with a third body, the first two bodies are likewise in thermal equilibrium with each other.
First Law of Thermodynamics
The first law of thermodynamics, generally known as the law of conservation of energy, asserts that energy cannot be generated or destroyed, but only transformed from one form to another.
Second Law of Thermodynamics
According to the second rule of thermodynamics, entropy in an isolated system always increases. Any isolated system progresses spontaneously toward thermal equilibrium—the system's highest entropy state.
Third Law of Thermodynamics
According to the third law of thermodynamics, when the temperature approaches absolute zero, a system's entropy approaches a constant value.
Thermodynamics Application in Daily Life
The use of thermodynamics is everywhere, whether we are sitting in an air-conditioned room or driving in any vehicle. Let’s look at some daily life applications of thermodynamic concepts.
The 2nd law of thermodynamics governs the operation of several types of vehicles such as planes, lorries, and ships.
Thermodynamics govern the three modes of heat transmission. Heat transfer concepts are used in radiators, heaters, and coolers.
Thermodynamics is used in the study of several types of power plants, including nuclear and thermal power plants.