Fundamentals of Thermodynamics

Thermodynamic word is derived from two words “Thermo”, which means heat, and “dynamics”, which means “change”. So, thermodynamics is a branch of science that deals with energy transfer and its effects on the physical and chemical properties of the substance. The amount of heat or work transfer taking place while arriving at one state from another is the main concern of thermodynamics. In simple words, we can say that the fundamental of thermodynamics is to study the relationship between energy, heat, temperature, and work. The four laws of thermodynamics govern the behaviour of these qualities. In 1749, William Thomson named this behaviour thermodynamics. Keep reading the notes for the fundamentals of thermodynamics definition, application, statements, and examples.

What are the Fundamentals of thermodynamics?

Thermodynamics is a branch of natural science concerned with heat and its relationship to work and energy. The chemical reaction is associated with energy change which means that energy is consumed to break chemical bonds, and energy is released when bonds are formed. The law of thermodynamics deals with the energy change of macroscopic systems involving several molecules. 

System and Surrounding

The system refers to the portion of the universe which is under observation. The surroundings refer to everything else in the universe except the system.
The Universe = The System + The Surroundings.

Types of Systems in thermodynamics

• Open system: It is the system in which matter and energy both can be exchanged with the surroundings.

• Closed system: It is the system in which only energy can be exchanged with the surroundings.

• Isolated system: The system in which neither energy nor matter can be exchanged with the surroundings.

Laws of thermodynamics

The first law of thermodynamics states that “energy can neither be created nor destroyed; it can only transfer from one form to another”. According to the First Law, a system’s internal energy must be equal to the work that is being done on it, plus or minus the heat that flows in and out of it and any other work that is done on it. This law is also known as the law of conservation. The mathematical equation for the first law of thermodynamics is:

ΔU = Q − W

The second law of thermodynamics states that the total entropy of an isolated system can never decrease. This law was proposed by different scientists.

• Kelvin Planck Statement: No process is possible whose sole result is the absorption of the heat from a reservoir and the complete conversion of the heat into work.

• Clausius Statement: No process is possible whose sole result is the transfer of heat from colder objects to hotter objects.

The mathematical equation for the second law of thermodynamics is:

dq/dξ = T(dS/dξ)

The third law of thermodynamics states that as the temperature of a system approaches absolute zero, its entropy becomes constant, or the change in entropy is zero. The third law of thermodynamics is known as the Nernst law. The mathematical equation for the third law of thermodynamics is:

S=klogW

Zeroth law of thermodynamics states that if two bodies, A and B, are in thermal equilibrium with another body C, bodies A and B will also be in thermal equilibrium with each other.

Limitations of Laws of thermodynamics

1. There are no restrictions on the passage of heat in either direction: the first law establishes a clear relationship between the heat absorbed and the work performed by a system. The first law does not state whether or not heat can travel from a cold to a hot end. For example, chilling ice to a low temperature will not extract heat from it. There is some outside work to be done.

2. Does not describe whether the reaction is viable: the first law does not specify whether a process is feasible or not. For example, equilibrium must be achieved when a rod is heated at one end, which is only attainable with some energy expenditure.

3. It is impossible to convert heat energy into an equivalent quantity of effort in practice. Another law, known as the second law of thermodynamics, is required to overcome these constraints.

Conclusion

Thermodynamics is one of the most crucial chapters of chemistry. This topic deals with energy transfer and its effects on the physical and chemical properties of the substance. Suppose you are looking for the fundamentals of thermodynamics study material. In that case, various types of thermodynamics are involved: Isothermal Process, Adiabatic Process, Isochoric Process, and Isobaric Process, to name a few.