The Third Law of Thermodynamics
Entropy versus temperature
Let's state the third law of thermodynamics. The law states that pure and perfect crystalline substances have an entropy of zero at 0 Kelvin. What does that mean? It means that a pure crystalline substance will have perfect order at absolute zero temperature. An increase in temperature will destroy this zero entropy. By looking at the graph (Figure 10-1), it is clear that an increase in temperature increases the entropy.