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U.S. Department of Energy
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Solution microcalorimeter for measuring heats of solution of radioactive elements and compounds

Technical Report ·
OSTI ID:6446137
The microcalorimeter vessel is constructed of tantalum metal, with a nominal volume of 5 cm/sup 3/. Its energy equivalent is 24 J K/sup -1/ when containing 5 cm/sup 3/ H/sub 2/O. The thermal leakage modulus is 0.010 min/sup -1/. A thermistor is employed as the temperature sensor. The operating sensitivity is about 1 x 10/sup -5/ K (300 ..mu..J). The performance of the calorimetry system was tested using tris(hydroxymethyl)aminomethane (TRIS) and magnesium metal. The results of the TRIS experiments, at a concentration of 1 g dm/sup -3/ in 0.1 N HCl at 298 K, yielded a heat of solution of -29.606 +- 0.063 kJ mol/sup -1/. The magnesium experiments, in 1 N HCl at 298 K, gave a heat of solution of -465.965 +- 1.136 kJ mol/sup -1/. The heat of solution of curium-248 metal in 1 N HCl at 298 K was measured. The experiments, which should not be considered definitive, yielded a heat of solution of -606.4 +- 1.8 kJ mol/sup -1/. A single measurement in 6 N HCl gave a heat of solution of -602.3 kJ mol/sup -1/. From these results the heat of formation of Cm/sup 3 +/ /sub (aq)/ is calculated to be -607.2 +- 2.5 kJ mol/sup -1/.
Research Organization:
Tennessee Univ., Knoxville (USA)
OSTI ID:
6446137
Report Number(s):
ORO-4447-081
Country of Publication:
United States
Language:
English