ENTHALPY OF FUSION AND TEMPERATURE OF FUSION OF INDIUM, AND REDETERMINATION OF THE ENTHALPY OF FUSION OF TIN

The molar enthalpy and temperature of fusion of a very pure sample of indium have been determined by adiabatic-shield calorimetry for the Laboratory of the Government Chemist, U.K. with the result: ΔfusHm = (3296±9) J·mol-1. Fractional-enthalpy-of-fusion determinations over the region (13.4 to 88.0) per cent molten indium are consistent with a mole fraction of (solid-insoluble but liquid-soluble) impurity of about 2·10-7 and Tu = (429.753±0.02) K. The present value for the molar enthalpy of fusion is 13 J·mol-1 higher than obtained earlier. A redetermination of the enthalpy of fusion of tin was therefore made. The resulting molar enthalpy of fusion is ΔfusHm = (7179±15)J·mol-1. This value is 16 J·mol-1 lower than obtained for a similar sample 18 a ago. The differences thus seem to indicate that the systematic errors are somewhat larger than expected at the time. © 1993 Academic Press. All rights reserved.