What is the First Law of Thermodynamics?

First Law of Thermodynamics states that the total energy of an isolated system is constant. Energy can be transformed from one form to another, but can neither be created nor destroyed.

Internal energy is a state variable in a thermodynamic system that is in equilibrium. The internal energy difference between the two systems is equal to heat transfer into the system minus work done by the system.

According to the First Law of Thermodynamics, the universe’s energy does not change. It can be transferred between the system and the surroundings, but it cannot be produced or destroyed. The law is primarily concerned with energy states as a result of work and heat transmission. 

We may use the popular example of a heat engine to help you grasp the meaning of the First Law. Thermal energy is transformed into mechanical energy in a Heat engine, and the process is also reversed. The majority of heat engines are classified as open systems. A heat engine’s primary working concept is to take advantage of the many interactions between heat, pressure, and volume of a working fluid, which is generally a gas. It’s not uncommon for gas to turn into a liquid and then back into a gas.

First Law of Thermodynamics adaptation of the Law of Conservation of Energy differentiates between three types of energy transfer: Heat, Thermodynamic Work, and Energy associated with matter transfer. It also relates each type of energy transfer to a property of a body’s Internal Energy.

The First Law of Thermodynamics states that energy cannot be created or destroyed however, it can be transferred from one form to another. Also, according to the first law of thermodynamics, Heat is a form of energy and the thermodynamic processes (like Isothermal, Isochoric, Adiabatic, Isothermal, and Quasi-Static Processes.) obey the Law of Conservation of Energy.