The study of relations between work, heat and temperature and their relations with energy, entropy, and physical properties of matter. Thermodynamics explain how matter is affected by the process when thermal energy is converted to or from the other forms of energy, and the process itself.
The energy that is released from heat is known as thermal energy. This generated heat allows the movement of particles within an object and as the speed of these particles increase, more heat is generated.
There are four laws of thermodynamics which are as follows-
Zeroth Law of Thermodynamics
First Law of Thermodynamics
Second Law of Thermodynamics
Third Law of Thermodynamics
Let us study the first law of thermodynamics in detail.
First Law of Thermodynamics- Explanation
The first law of thermodynamics states that the quantity of the heat absorbed, when some amount of heat is given to a system that is capable of doing external work, is equal to the sum of the increase in internal energy of the system due to a rise in temperature and external work done during expansion.
The first law of thermodynamics is generally represented by the equation-
\[\Delta U = Q -W\]
Where \[\Delta U\] = change in internal energy of the thermodynamic system
\[\Delta Q\] = heat given to the system
\[\Delta W\] = work done on the system
Differential form of the first law of thermodynamics equation-
dU - dQ - dW
The first law of Thermodynamics is also called ‘Law of Conservation of Energy’. The law of conservation of energy states that “Energy can neither be destroyed nor be created, it can only be transferred from one form to another”.
Significance of First Law of Thermodynamics
Significances that the first law of thermodynamics has are as follows-
The relation between heat and work is established by the first law of thermodynamics.
Both Work and Heat are equivalent to each other.
The exact equivalent amount of energy of the surrounding will be lost or gained, if any system gains or loses energy.
Applied heat is always equal to the sum of work done and change in internal energy.
The energy is constant for an isolated system.
Applications of First Law of Thermodynamics
The first law of thermodynamics is commonly used in heat engines.
Refrigerators is another example where the first law of thermodynamics is used.
Sweating is a great example of the first law of thermodynamics since the heat of the body is transferred to sweat.
When an ice cube is put in a drink, the ice cubes absorb the heat of the drink which makes it cool.
Limitations of First Law of Thermodynamics
The first law of thermodynamics does not state anything about the heat flow direction.
The process is not reversible.
It is difficult to distinguish whether the process is spontaneous or not.