Laws of Thermodynamics

Underlying principles that govern all energy changes.

First Law Statements:
Second Law Statements:
All chemical and physical changes occur such that:
   The total organization of the universe decreases ,
   The total disorganization of the universe increases .

The internal energy of the universe is constant.
 The entropy of the universe is always increasing.

The change in the internal energy of the universe is zero.
      ΔUuniverse = 0

The change in the entropy of the universe is positive.       
        ΔSuniverse > 0         (= 0 for reversible change)
The sum of energy changes in the system and surroundings is zero
    ΔUuniverse = ΔUsystem + ΔUsurroundings = 0
 The sum of entropy changes in the system and surroundings is > zero.
   ΔSuniverse = ΔSsystem + ΔSsurroundings > 0   (= 0 for reversible change)
The internal energy of the an isolated system is constant .
        ΔUsystem = 0
Order never spontaneously increases in an isolated system.         
                 ΔSsystem > or = 0