Specific Heat of Sodium from 300 to 475°K

Abstract

The specific heat of 99.99% pure sodium has been measured from 300 to 475°K using an adiabatic calorimeter. The melting point of pure sodium is estimated as 371.01±0.005°K and the latent heat as 620.95±0.30 cal/g-at. The specific-heat and melting results are in good agreement with earlier drop-calorimetry results of Ginnings, Douglas, and Ball. If the rapid increase of specific heat in the solid is ascribed to the thermal generation of lattice vacancies, a formation energy of 8.2±1.2 kcal/mole is obtained. A new and simple derivation is given of the basic equation used in Mastrangelo and Dornte's method for analyzing the melting of substances with solid soluble impurities.