12.16 Deviations from Dulong and Petit′s Laws
Extensive researches by Magnus, Nernst and Lindemann, and Lewis conclusively prove that specific heats of substances actually vary with temperature. The curves in Fig. 12.12 show the nature of variation of Cv with temperature.
Fig. 12.12 Variation of specific heat of some substances with temperature
The atomic heat of diamond rises from a low value of 0.03 at 86.5 K to 5.077 at 1100 K. All light substances such as boron, beryllium and silicon behave in a similar manner.
At room temperature, atomic heat of lead approximates the value required by Dulong and Petit.
But below 100 K, it drops rapidly ...
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