WHAT IS THERMODYNAMICS?
Thermodynamics is the large scale study of the effect of heat and energy on matter.
THE EVOLUTION OF THERMODYNAMICS
It all started with need. France was in the middle of a war, and Carnot believed that engines were the key to a French victory. Steam engines were prevalent at that time, and everyone believed that they were key to innovation and development. Carnot provided the model for the ideal steam engine, and gave the idea that the efficiency of his engine depended only on temperature, and not other factors.
However, the next major contributions to thermodynamics (which made “thermodynamics”) were undertaken by Rudolf Clausius (who introduced entropy), Lord Kelvin (formulated the 2nd law of thermodynamics) and William Rankine (who did work on the efficiency of heat engines and introduced a scale for temperature).
LAWS OF THERMODYNAMICS
The “Zeroeth” law of Thermodynamics states that if 2 systems are in thermal equilibrium with a separate third system, they are in equilibrium (thermal) with each other.
The First Law of Thermodynamics states that the energy of an isolated system remains constant. If the system is not isolated, it’s change in energy (internal energy), that is, ΔU= Q-W, where Q is the energy supplied to a system (heat which may be transferred into the system or be taken out of it) and W is the work done on it, or by it (It’s negative if work is done on it, and vice versa). Also, if 2 systems merge together (as in a chemical reaction), the new internal energy will be the sum of the initial internal energies of the 2 systems.
The Second Law of Thermodynamics states that the entropy of a system can never decrease. That is, things keep on getting more disordered as time progresses. Heat flows from high temperature to lower temperature (leading to a positive change in entropy), much like a ball falls down from a state of higher gravitational potential energy to a lower one. For the vice versa to happen, energy has to be supplied (leading to a negative change in entropy).
The Third Law of Thermodynamics tells us what would happen if the temperature kept on decreasing. Absolute zero temperature would cause for minimum entropy and all processes would cease.
IMPLICATIONS OF THESE LAWS
Thermodynamics discusses energies internal to a system, while traditional energies (like potential and kinetic energies) are more about outside-the-system energies.
It has allowed us to use energy to our advantage in a much more systematic way, since it tells us how to minimize energy losses due to friction and heat generation.
The steam engine was revolutionized eternally with the help of thermodynamics, and the ACs we use today are based upon the principle of heat and cold. Home heating systems and Solar energy systems are too reliant on thermodynamics. We can calculate the heat released during a chemical reaction with the help of its principles, and it has been applied in food preservation techniques (refrigerators).
Effectively, thermodynamics answers the following question:-
“How do environmental changes affect a system?”.
This question’s answer is of great importance, as a system can be considered an isolated application of Thermodynamics. So, wherever you see heat (that’s pretty much everywhere), Thermodynamics is involved.
