Limitations Of First Law Of Thermodynamics
The first law of thermodynamics tells us that energy can be changed from one form to another but can be neither created nor destroyed in any process. The mathematical expression which is used to represent the first law of thermodynamics is DE = q-w, where DE refers to the internal energy change of the system when 'w' amount of work is done by the system when it absorbs 'q' amount of heat and carries out 'w' amount of work. However, this law possesses many limitations such as given below.
1. The first law of thermodynamics merely indicates that in any process there is a transformation between the various forms of energy involved in the process but provides no information regarding the feasibility of such transformation.
2. First law does not provide any information regarding the direction a processes will take whether it is a spontaneous or a non spontaneous process.
SECOND LAW OF THERMODYNAMICS
"It is impossible to construct an engine which operated in a complete cycle will absorb heat from a single body and convert it completely to work without leaving some changes in the working system". This is called as the Kelvin - Planck statement of II law of thermodynamics.