Thermodynamics:

Thermodynamics is scientific study of work, heat, and related properties of chemical and mechanical systems. A thermodynamic process can be defined as the energetic evolution of a thermodynamic system proceeding from an initial state to a final state. Thermodynamics is study of energy changes accompanying chemical and physical changes. The 7 most common thermodynamic processes can be given as: An isobaric process takes place at constant pressure, An isochoric process, takes place at constant volume, An isothermal process occurs at a constant temperature, An adiabatic process occurs without loss or gain of energy by heat, An isentropic process occurs at constant entropy, An isenthalpic process occurs at a constant enthalpy, A steady state process takes place without a change in the internal energy of a system.

Applications of thermodynamics are based on four fundamental laws that deal with energy and entropy changes. The laws of thermodynamics can't be derived.

In thermodynamics, there are 4 laws which do not depend on the details of the systems under study or how they interact. These 4 laws are given as follows:

Zeroth law of thermodynamics, about the thermal equilibrium:

If 2 thermodynamic systems are separately in thermal equilibrium with a third, they are in thermal equilibrium also with each other.

If we grant that all systems are in thermal equilibrium with themselves, the Zeroth law implies that thermal equilibrium is an equivalence relation on the set of thermodynamic systems. This law is tacitly supposed in every measurement of temperature. Therefore, if we want to know if 2 bodies are at the same temperature, it is not necessary to bring them into contact and to watch whether their observable properties change with time.

First law of thermodynamics, for the conservation of energy:

The change in the internal energy of a closed thermodynamic system is equal to the sum of the quantity of heat energy supplied to or removed from the system and the work done on or by the system.

Second law of thermodynamics, for entropy:                                                                                      

The total entropy of any isolated thermodynamic system always increases over time, approaching a maximum value or also stated as, "In an isolated system, the entropy never decreases".

Third law of thermodynamics, for the absolute zero of temperature:

As a system asymptotically approaches absolute zero of temperature all the processes virtually cease and the entropy of the system asymptotically approaches the minimum value; can be stated as: the entropy of all systems and of all states of a system is smallest at absolute zero or equivalently it is not possible to reach the absolute zero of temperature by any finite number of processes.