Thermodynamics is a branch of physics which deals with the relationships between heat, energy and work within a system. It deals with energy transformation, constraints on doing work, and the consequences of changes to the physical state of a system in relation to changes in its environment. So, in other words thermodynamics help us describe how heat and energy work. It helps us understand which processes will happen by themselves and which are essentially impossible.

You might think that thermodynamics is something highly theoretical, but it has a practical application in many facets of our day-to-day life. Thermodynamics is the science of energy transfer, and it applies to everything from boiling water to running an engine.

Systems and Surroundings

System: In thermodynamics, a system is the specific part of the universe that is being investigated or examined. This is the part of an energy transfer, heat exchange, matter interaction analysis. The rest of the universe makes up this boundary, which can be real or imaginary and fixed or movable.

Surrounding: The surroundings are anything outside the system with which the system can exchange energy in a thermodynamics process. It is, essentially — that part of the universe beyond the wall to the system you are studying.

Open systems, by contrast, can receive heat and work form the surroundings as well as matter. If one thinks of a pot of boiling water as the system, its surroundings would be the stove and air that is floating off-boil from this pot.

There are three types of Thermodynamic systems, Open, Closed and Isolated systems.

Open System

An open system can exchange both energy (heat or work) and matter with its surroundings. Example: A boiling pot of water where both steam (matter) and heat can leave the system.

Closed System

A closed system can exchange energy (heat or work) but not matter with its surroundings. Example: A sealed container of gas that can be heated or cooled, changing its energy but not losing or gaining gas particles.

Isolated system

An isolated system does not exchange either energy or matter with its surroundings. It is completely insulated from any external influence. Example: A perfectly insulated thermos bottle (in an ideal case) where neither heat nor matter can enter or leave.

Laws of Thermodynamics

The four laws of thermodynamics form the foundation of understanding how energy behaves in physical systems. These laws outline the principles governing heat, energy transfer, and the relationship between energy and matter. Here is a breakdown of each of the four laws:

Zeroth Law of Thermodynamics

Statement: If any two systems A and B are in thermal equilibrium with a third system C, then the third system is also in thermal equilibrium with the first one.

Explanation: The Zeroth Law introduces the concept of temperature and thermal equilibrium. This law holds essentially that if two objects are in thermal equilibrium with the third object, they are also in mutual thermal equilibrium. This law is fundamental because it let us use thermometers as a means to measure temperature.

Significance: It is the basic law for temperature measurement. Otherwise, without this law, temperature could not be defined in consistent terms. This law ensures temperature as a transitive property and offers the base for other laws of thermodynamics.

1st Law of Thermodynamics

Statement: The First law of Thermodynamics is basically the Law of Conservation of Energy. It states that the energy can neither be created nor destroyed, it can only be transferred from one form to other form.

Mathematically: ΔU=Q−W

Where ΔU = Change in internal energy of the system

Q = Heat added to the system

W = Work done by the system

Explanation: The first law essentially is the law of conservation of energy. This law states that the total energy of an isolated system remains constant. Thus, any change in the internal energy of a system is due to energy entering through heat or being taken away as work. For example, when gas in a cylinder undergoes compression, its internal energy increases due to the work done on the gas, thereby increasing the temperature.

Significance: This law is to be important in quite a number of processes such as power generation, engine workings, and heating systems as such energy accounts balance out.

2nd Law of Thermodynamics

Statement: The Second Law of Thermodynamics states that in any energy transfer, the total entropy (disorderness) of any isolated system can never decrease. It either increases or remains the same. Entropy always tends to increase with time, making the natural direction of spontaneous processes one from order to disorder.

Explanation: Entropy is a measurement of the amount of randomness or disorder in a given system. The Second Law shows that natural phenomena always tend toward maximum entropy. Natural processes, for instance, transfer heat from a hotter object to a cooler one, making the entropy of the whole system increase. Simply put, energy tends to disperse or spread out unless work is being done to keep things orderly.

Significance: The Second Law explains why certain processes are necessarily irreversible, like ice melting or two different gases mixing. It also puts an upper limit on the efficiency of energy conversion processes so that a perfect machine, such as a perpetual motion machine, cannot be built.

3rd Law of Thermodynamics

Statement: As the temperature of a system approaches absolute zero (0 Kelvin), the entropy of the system approaches a constant minimum value, usually zero for a perfectly ordered crystal.

Explanation: The Third Law of Thermodynamics says that when one cools a system to absolute zero, particles lose most of their kinetic energy and become absolutely ordered. Since entropy is a measure of disorder, it approaches its lowest possible value. However, from a practical point of view, absolute zero can’t be achieved because the last particle of thermal energy has to be removed from a system through an infinite amount of work.

Significance: It is significant in cryogenics and materials science, as it prescribes how matter must behave at extremely low temperatures. It also gives zero point for calculating absolute entropy, explaining why perfect order is not possible in the world.

Real life examples of Thermodynamics

We see Thermodynamics in so many daily activities. Some of the real-life examples of Thermodynamics are:

1. Boiling water on a stove

You, for example are experiencing the concept of thermodynamics when you put a pot on top of a stove and turn up the heat. That is because once the stove starts to warm, it conducts heat energy from itself to the water in the pot. With this energy transfer, the speed of the motion increases. This increases their kinetic energy and, hence, raises the temperature of the water.

The water then starts boiling, and through this process undergoes a phase change from a liquid to a gas in the form of steam. This also takes some extra energy, known as the latent heat of vaporization. In summary, the whole process exemplifies the First Law of Thermodynamics, which states that the system cannot create or destroy energy but can only transfer or transform it.

Key Concepts in Action: Heat transfer, energy conversion, phase change.

2. Refrigerator Cooling

Refrigerators really make the story of the Second Law of Thermodynamics perfect. Refrigerators transfer the heat absorbed from their interior to an exterior environment so that, in such a manner, it decreases inside refrigerators for keeping food.

Inside the fridge, the refrigerant takes heat from food and converts it into gas. In that gaseous state, the system compresses it to raise its temperature further, then cools it again and condenses it into the liquid state. The system releases the sucked-up heat into the surroundings, continuing this cycle to maintain a cool temperature inside the refrigerator.

This process shows that the system reduces the entropy inside the fridge at the expense of energy (electricity), but simultaneously increases the entropy in the surroundings as a result of heat release.

Key Concepts in Action: Heat transfer, work (compression of the refrigerant), entropy change.

3. Car Engine Operation

For instance, the car engine is a heat engine that illustrates one form of heat engine, working in accordance with First and Second Laws of Thermodynamics. Combustion in an internal combustion engine has to do with a hot gas produced by burning fuel in air. The gas expands and pushes pistons, transforming the thermal energy into mechanical work used to propel the vehicle.

However, the system does not convert all the energy from the fuel into useful work. It loses some of it as heat to the surroundings and exhaust gases. This shows the Second Law of Thermodynamics. An engine cannot be efficient at 100 percent because some energy is always dissipated into waste heat.

Key Concepts in Action: Energy conversion (chemical to thermal to mechanical), work, heat loss, engine efficiency, and entropy.

Why is Thermodynamics Important

Thermodynamics isn’t just theoretical—it has practical applications in various fields, including:

• Engineering: Designing engines, refrigerators, power plants, and HVAC systems.
• Chemistry: Understanding reactions, energy changes, and equilibrium.
• Environmental Science: Studying energy consumption, climate change, and natural processes.
• Biology: Exploring metabolism, energy flow in ecosystems, and physiological processes like sweating.

Conclusion

Thermodynamics is a fundamental aspect of science that explains how energy and heat move within different systems, from household appliances to natural processes in our bodies. By observing real-life examples, such as boiling water, engine operation, and even the way we sweat, we can see how the laws of thermodynamics govern everyday phenomena.

Understanding these principles not only deepens our knowledge of the world around us but also equips us to innovate and develop technologies that harness energy more efficiently and sustainably.