Problems are listed in approximate order of difficulty. A single dot (•) indicates straigh...

Problems are listed in approximate order of difficulty. A single dot (•) indicates straightforward problems involving just one main concept and sometimes requiring no more than substitution of numbers in the appropriate formula. Two dots (••) identify problems that are slightly more challenging and usually involve more than one concept. Three dots (•••) indicate problems that are distinctly more challenging, either because they are intrinsically difficult or involve lengthy calculations. Needless to say, these distinctions are hard to draw and are only approximate.

•• The Dulong–Petit law predicts that the molar specific heats (that is, the heat capacity per mole) of elemental solids should all have the same value, C = 3R. On the other hand, the ordinary specific heats c, defined as the energy per degree per mass, can be quite different. (a) Prove that the specific heats, c, of elemental solids obeying the Dulong–Petit law are inversely proportional to the atomic masses. (b) Given the following data, check the accuracy of this prediction.