Basic Physics of THERMODYNAMICS

Thermodynamics is based on three postulates, known as the Law of Thermodynamics I, Thermodynamics Second Law of Thermodynamics and the Law III.
1. Law of Thermodynamics I

The first law of thermodynamics states the relationship between heat (q), work (w) and changes in energy (ΔU), who explains that the energy-insulated system is fixed. The first law of thermodynamics can be expressed by the following equation:
q = ΔU - W
q, ΔU, danW in units of joules or calories. The first law of thermodynamics indicates that the energy can not be measured but can be measured from the heat and work. Heat can be measured by experiment and work. Work is calculated through the volume and pressure against the change.
2. Second Law of Thermodynamics

The second law of thermodynamics suggests that all processes or reactions that occur in the universe, is always accompanied by an increase in entropy. Change in entropy (dS) is a state function which is a comparison of changes dipertukaran heat between system and environment in a reversible (δqrev) to a certain temperature T (° C). The equation that states the amount of entropy is expressed as follows:
dS = δqrev / T
3. Law of Thermodynamics III

The third law states that an element or pure compound in the form of a perfect crystal has zero entropy at a temperature of 0oC, mathematically expressed as follows:
Soo = 0
Based on the third law can be carried out measurements and calculation of the absorbed heat of a pure substance from 0oK until a certain temperature. Work that can be obtained from the amount of heat equal to the amount of heat reduced a portion of that amount.
The system is part of the world of special concern for our world. The system can be either a test tube, machinery, electrochemical cells, and so on. In the vicinity of existing systems environment, where we make observations. By setting a limit of the system and its environment we can get a thorough specification of the boundary between the two. If the matter can be transferred through the boundary between the system and its environment, then the system is said to be open. Conversely, if the material can not be moved to say as a closed system. Closed system that has no mechanical or thermal contact with its environment is called an isolated system.
A system may experience a variety of processes according to her circumstances. The situation is such that one system variables constant. Various processes are:
1. Isothermal process, which is a process which takes place at constant temperature (T1 = T2), resulting in a fixed energy.
2. Isovolum process, which is a process that does not change the volume (DV = 0), consequently the system does not do the job.
Adiabatic processes, ie processes that do not absorb or release heat, which means the energy in the system used to generate employment