ON THE SPECIFIC HEATS OF TUNGSTEN, MOLYBDENUM, AND COPPER

Abstract

This paper contains the results of a long series of determinations of the specific heats of tungsten, molybdenum, and copper from − 20° to 500 °C.A new type of all-copper adiabatic calorimeter has been designed and used. The complete elimination of water from the calorimeter removed several sources of error and resulted in increased reliability and accuracy.Two entirely different methods were used in determining the specific heats. The usual "method of mixtures" was used to determine the mean specific heat for a large temperature change and was applied to all three metals over the entire range of temperature. The specific heat of copper was also determined for 5- or 10-degree intervals from − 5° to 110 °C. by heating the calorimeter electrically.It has been quite definitely shown that the specific heats of these metals over a temperature range as large as 0° to 500 °C. cannot be expressed as a linear function of the temperature. An equation of the form Cp = A + BT − C/T2 was arrived at from theoretical considerations and the constants determined empirically with the following results:—[Formula: see text]where the unit of heat is the 20-degree calorie and T is absolute temperature. The average deviation of the individual determinations from the values calculated by these equations was only about 0.1%.As a matter of convenience and for purposes of comparison, linear equations applicable over smaller ranges of temperature have also been given.