Thermodynamics

Thermodynamics is the science  dealing with energy conversion like conversion of mechanical work to heat and heat to mechanical   energy. Temperature, pressure and volume are also involved in thermodynamics. It has got many practical applications in branches of science and engineering. It deals with energy processes that convert heat energy from available sources to mechanical energy. Many analytical and theoretical methods are used in the field of thermodynamics to covert energy from one form to another. Many scientists like Carnot, Robert Hooke, Robert Boyle, and Thomas Savrey have contributed a lot to the field of thermodynamics. Instruments like Thermometer, Carnot engine are the outputs of thermodynamics.   The major four laws of thermodynamics define physical quantities such as temperature, energy and entropy. Using these laws thermodynamic systems can be described and the energy conversion occurring in thermodynamic processes are explained.

Zeroth Law

Zeroth law states that when two systems A & B are in equilibrium with C, then the system A is also in thermal equilibrium with B. According to Zeroth law thermal equilibrium is a binary relation or Euclidean relation. It can be also equivalence relation and the binary relationship between systems in chemical equilibrium can be reflexive. Zeroth law is a statement about measurability. This law makes empirical parameter, the temperature, as a property of system, such that systems in equilibrium have same temperature.

First Law of Thermodynamics

According to the first law of thermodynamics matter can be neither created nor destroyed. It can be converted from one form to another. In all processes in an isolated system, the total energy remains same. For any thermodynamic circle the net heat supplied to the system equals the net work done by the system. The nature of energy is defined in the first law of thermodynamics. First law can be expressed as:

Increase in internal energy of a system  =  work done on the system +  heat supplied for the functioning of system

Second Law of Thermodynamics

When two isolated systems, which are not in equilibrium with each other, but in equilibrium in itself, are allowed to interact, breaking the isolation that separates the two systems .They exchange matter and energy to reach mutual thermodynamic equilibrium. In short second law states that entropy (quantitative measure of disorder in a system) of a closed system will increase with time and it can never be decreased.

Third Law of Thermodynamics

Third law states that the entropy of a perfect crystal is exactly equal to zero when it is at absolute zero. This law is well explained by statistical mechanics using the fact that a perfect crystal has only one microscopic state. Entropy is related to the number of possible microstates.

Questions:

• Define thermodynamics?
• Explain Zeroth law of thermodynamics?