Thermodynamics and Laws of Thermodynamics

Thermodynamics and Laws of Thermodynamics

Thermodynamics deals with the principles of heat and temperature and the inter-conversion of heat and other forms of energy. The four laws of thermodynamics govern the behavior of these amounts and offer a quantitative description. William Thomson, in 1749, created the term thermodynamics.

The word “Thermodynamics” is derived from two Greek words “thermes” and “dynamikos” which suggests heat and powerful respectively.

System or Surroundings

In order to avoid confusion, researchers discuss thermodynamic values in reference to a system and its surroundings. Everything that is not a part of the system constitutes its surroundings. The system and surroundings are separated by a boundary.

For example, if the system is one mole of a gas in a container, then the boundary is simply the inner wall of the container itself. Whatever beyond the boundary is thought about the surroundings, which would consist of the container itself.


Types of Systems

There are three types of system:

Isolated System

An isolated system cannot exchange both energy and mass with its surroundings. The universe is thought about an isolated system.

Closed System

Throughout the limit of the closed system, the transfer of energy happens however the transfer of mass doesn’t take place. Fridge, compression of gas in the piston-cylinder assembly are examples of closed systems.

Further Reading:  Modulus of Elasticity and Types
Open System

In an open system, the mass and energy both may be transferred between the system and surroundings. A steam turbine is an example of an open system.

Laws of Thermodynamics

The laws of thermodynamics define the essential physical amounts like energy, temperature level and entropy that identify thermodynamic systems at thermal equilibrium. These thermodynamic laws represent how these quantities behave under various situations.

There are four laws of thermodynamics and are provided below:

  • Zeroth law of thermodynamics
  • The first law of thermodynamics
  • The second law of thermodynamics
  • Third law of thermodynamics
Zeroth law of thermodynamics

If two thermodynamic systems are each in thermal equilibrium with a third, then they remain in thermal equilibrium with each other.

The First Law of Thermodynamics

The first law of thermodynamics also referred to as the Law of Conservation of Energy, specifies that energy can neither be created nor be destroyed; energy can just be transferred or altered from one kind to another. For example, turning on a light would seem to produce energy; however, it is electrical energy that is transformed.

A method of expressing the first law of thermodynamics is that any change in the internal energy (∆ E) of a system is given by the sum of the heat (q) that streams across its boundaries and the work (w) done on the system by the surroundings:

∆ E = q + w

The Second Law of Thermodynamics

The second law of thermodynamics states that the entropy of any isolated system constantly increases. Isolated systems spontaneously develop towards thermal equilibrium– the state of optimum entropy of the system. More simply put: the entropy of the universe (the ultimate isolated system) just increases and never decreases.

Further Reading:  Fluid Flow and Equation of Continuity

An easy way to think of the second law of thermodynamics is that a room, if not spick-and-span, will usually end up being untidier and more disorderly with time– regardless of how cautious one is to keep it tidy. When space is cleaned, its entropy reduces, however, the effort to clean it has led to a boost in entropy outside the room that surpasses the entropy lost.

Third Law of Thermodynamics

The Third Law of Thermodynamics says that a perfect crystalline structure at absolute zero temperatures will have zero disorder or entropy. Nevertheless, if there is even the tiniest tip of the flaw in this crystalline structure, then there will likewise be a minimal quantity of entropy.

This law gets a little weird though, because even at absolutely zero Kelvin there is still some atomic motion happening, so it’s a bit theoretical. Regardless, this law permits us to comprehend that as the entropy of a system approaches a temperature of absolute zero, the entropy present within a system decreases.