what is dulong-petit law?
The specific heat of copper is 0.093 cal/gm K (0.389 J/gm K) while that of lead is only 0.031 cal/gm K(0.13 J/gm K). The difference is primarily because it is expressed as energy per unit mass. If it is expressed as energy per mole, they are very similar.
It is in fact that similarity of the molar specific heats of metals which is the subject of the Law of Dulong and Petit.
The similarity can be accounted for by applying equipatition energy to the atoms of the solids.
This law isn't precisely true, and isn't always true, and is never true at low temperatures. But it captures some physics that is equipartition theorem.
Dulong-Petit's law as:
Energy per mole: 3kTNA
k = Boltzmann constant
T = Temperature in kelvin
NA = Avogadro's number
Dulong and Petit law:
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