First Law of Thermodynamics: A Detailed Introduction

As stated in the first law of thermodynamics, energy can neither be created nor destroyed; it can only be transformed in form. Whenever mass crosses the control boundary, external work is performed, or heat transfers across the boundary, energy transfer is associated with that system. These have an effect on the amount of energy that has been stored within the control volume.

First and foremost, because it is an extension of the law of conservation of energy, which states that energy can neither be created nor destroyed, the first law of thermodynamics is widely regarded as the most straightforward to understand. The amount of energy present at the beginning and end of the universe will be the same as it was at the beginning of the universe. Furthermore, in a manner similar to the zeroth law, which served as a catalyst for the introduction and clarification of the property “temperature,” the first law serves as a catalyst for the introduction and clarification of the elusive concept of “energy,” as well as its clarification.

A process’s energy balance is developed in accordance with the first law of thermodynamics in order to better understand it, to assist in design and control, to identify areas for process improvement, and to allow for eventual optimization of the process. Comparing the degree of perfection in the process’s energy utilization, or in specific parts of the process, allows comparison with the degree of perfection, as well as the related process parameters, in other comparable processes. Specifically, it is critical to compare current achievable values in the most energy-efficient systems. Priorities can be established for the optimization attempts that are required for a system or its constituent parts. Excessive energy consumption or a particularly low degree of perfection are both acceptable justifications for implementing such priorities.

In contrast, there are some shortcomings to the energy approach. As a rule, the assumed direction of a process has no effect on the energy exchange; for example, energy analysis allows heat to be transferred spontaneously in the direction of increasing temperature. The quantity of energy does not differ according to its quality; for example, 1 watt of heat is equal to 1 watt of work or electricity.

A system’s total energy does not change when it is converted from one form to another, according to the first law of thermodynamics. A car’s kinetic energy (the energy that an object has when it moves) is converted into heat energy when a driver applies the brakes to slow it down. The first law of thermodynamics establishes a relationship between the various forms of kinetic and potential energy present in a system and the amount of work and heat transfer that the system is capable of performing. A variation of this law is used to define internal energy in some cases, and it also introduces the concept of enthalpy as a new state variable. In accordance with the first law of thermodynamics, there are an infinite number of possible states for a system. Past experience, on the other hand, has shown that only specific states can occur. This eventually leads to the second law of thermodynamics and the definition of entropy, which is yet another state variable in the equation.

Moving against an opposing force is what is meant by the term “work.” Exerting effort to lift a heavy object against the opposing force of gravity is necessary. The mass of the object, the strength of the gravitational pull on it, and the height attained all contribute to determining the magnitude of the work involved. Work is a fundamental building block of thermodynamics, and in particular the first law of thermodynamics, it is the most important. Each and every system possesses the ability to perform work. Work can be performed by a spring that has been compressed or extended, for example, when lifting a weight. As a result of the fact that it can be connected to an electric motor, which can then be used to lift a weight, an electric battery has the ability to perform work. The fact that an electric current passes through a heater and causes it to heat up does not immediately stand out, but it does because the same current could be used to lift a weight by passing it through an electric motor rather than through the heater.

The first law of thermodynamics is also known as the law of conservation of energy because it conserves the amount of energy available. Elementary physics courses emphasize the conservation of mechanical kinetic and potential energy, as well as the relationship between mechanical kinetic and potential energy and the production of work. The effects of heat transfer and internal energy changes are included in a more comprehensive definition of energy conservation. The first law of thermodynamics is referred to in its more general form as the first law of thermodynamics. Electrostatic energy, magnetism, strain energy, and surface energy are examples of types of energy that can be included.

From the standpoint of thermodynamics, a term to denote a system’s capability of performing work is required in order to comprehend and have a better understanding of the term “work.” This is referred to as “energy.” Unstretched springs are more capable of performing work than springs with only a slight amount of stretch. Water with a higher energy content than cold water has a lower energy content per litre of water. The concept of energy is thus reduced to being simply a measure of the capacity for work performed by a system.

There Are Three Different Kinds of Systems

1. A system that is isolated- When a system is isolated, no matter nor energy can enter or leave the system at any point. 
2. A system that is closed- A closed system, on the other hand, can only interchange energy with its surroundings and cannot exchange matter with its surroundings.
3. A system that is open – An open system is capable of exchanging both energy and matter with its environment. The stovetop, for example, would be considered an open system due to the possibility of heat and water vapor being lost to the atmosphere.

The open system, which is the most general of the three, allows mass, heat, and external work to cross the control boundary without being controlled. Due to the fact that all energies entering the system equal the same amount of energies leaving the system, as well as a change in the storage of energies within the system, work expresses balance.

Conclusion

According to the first law of thermodynamics, energy cannot be created or destroyed; it can only be changed in form. When applying the first law of thermodynamics to an open system, the amount of energy entering the system equals the amount of energy leaving the system, according to the law.