Re: what are the laws of Thermodynamics

You should be able to find descriptions of the laws of thermodynamics in your 
library.  If not, and the third law is one that is not described in just any 
textbook, I found the following descriptions.

Zeroth law of thermodynamics - "... If two systems are in thermal equilibrium, 
then they must have the same temperature.  If each is in equilibrium with a 
third, then all three have the same temperature, and hence any two or all three 
are in thermal equilibrium.  This notion is sometimes called the zeroth law of 
thermodynamics.  It is actually an implicit part of the concept of 
temperature." [p. 62, ref 1]

Zeroth law of thermodynamics - "There exists a useful thermodynamic quantity 
known as temperature." [p. 526, ref 2]

Zeroth law of thermodynamics - "... a postulate often called the zeroth law of 
thermodynamics: If A and B are in thermal equilibrium with a third body C 
(the "thermometer"), then A and B are in thermal equilibrium with each other." 
[p. 526, ref 2]

First law of thermodynamics - "The first basic principle of thermodynamics is 
that matter has energy, and energy is conserved; we call this idea the first 
law of thermodynamics." [p. 45, ref 1]

First law of thermodynamics - "There exists a useful thermodynamic quantity 
known as internal energy." [p.561, ref 2]

First law of thermodynamics - "...may express the first law in words by saying: 
Every thermodynamic system in an equilibrium state possesses a state variable 
called the internal energy U whose change dU in a differential process is given 
[by the equation

     dU  =  dQ  -  dW,

where dQ is an infinitesimal amount of heat added to the thermodynamic system,
and dW is an infinitesimal amount of work done by the system]". [p. 561, ref 2]

Second law of thermodynamics - "The second law of thermodynamics is the 
postulate that:  The entropy of an isolated system can never decrease." [p. 
157, ref 1]

Second law of thermodynamics - "There exists a useful thermodynamic quantity 
called entropy". [p. 638, ref 2]

Second law of thermodynamics - "A natural process that starts in one 
equilibrium state and ends in another will go in the direction that causes the 
entropy of the system plus environment to increase." [p. 638, ref 2]

Third law of thermodynamics - "...we make the following macroscopic postulate:  
The temperature of any pure substance in thermodynamic equilibrium approaches 
zero as the entropy approaches zero.  Conversely, since the temperature is a 
monotonic function of the entropy, the energy of any pure substance in 
thermodynamic equilibrium approaches zero as the temperature approaches zero." 
[p. 370, ref 1]

"[Or, for a pure substance in equilibrium, the limit of the entropy as the 
temperature approaches zero is equal to zero,] this particular form of the 
postulate is called the third law of thermodynamics." [p. 370, ref 1]

Reference 1:  Reynolds and Perkins, Engineering Thermodynamics, 1970.

Reference 2:  Halliday and Resnick, Physics, 1966.

Thanks for your question.

sid