Statement of various law's

1. First law of thermodynamics 

Statement -: For a closed system undergoing a cycle net heat transfer (∑Q) is always equal to the net work transfer (∑w).

[ ∑Q = ∑w ] ( valid for cycle)

First law of thermodynamics is nothing but conservation of energy .

dQ = dE + dW     dQ = heat suply

dE = internal energy  dW = Work done

 This is the first law of thermodynamics for closed system undergoing a process .

( reversible and irreversible)

dW = P . dV 

For reversible process - dQ = dE + P.dV

Statement- when kinatic energy and poten tial energy are neglected. 

Second law of thermodynamics-:First law of thermodynamics says that energy is constant. It does not give any direction for a perticular process .

Second law of thermodynamics given diection of process, the concept of entropy  , hence this also known as directional law .

Calcius statement -: It is impossible to transfer heat from lower temperature to higher temperature without any external input .