Ludwig Boltzmann, 1877
S = k ln W
S = entropy, W = the number of ways of arranging the components of a system having equivalent energy, and k = the Boltzmann constant = R/NA (R = universal gas constant, NA = Avogadro’s number) = 1.38 x 10-23 J/K.
A system with relatively few equivalent ways to arrange its components (smaller W) has relatively less disorder and low entropy.
A system with many equivalent ways to arrange its components (larger W) has relatively more disorder and high entropy.
DSuniv = DSsys + DSsurr > 0
The Second Law of Thermodynamics
Entropy is a state function.
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