Thermodynamics of the actinide elements. Part I. Heats of formation of crystalline neptunium tetrachloride, neptunium oxide dichloride, and neptunium trioxide monohydrate, and a new determination of the heat of formation of the Np III and Np IV ions in M-hydrochloric acid
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 2995-2998
- https://doi.org/10.1039/j19690002995
Abstract
The following heats of solution have been measured: neptunium metal in oxygen-free 1M-HCl, to yield NpIII, –126·2 ± 0·2 kcal. mole–1; neptunium metal in 1M-HCl–0·005M-Na2SiF6 to yield NpIV, –166·0 ± 0·2 kcal. mole–1; NpCl4(c) in 1M-HCl and 1M-HCl–0·005M-Na2SiF6, –53·87 ± 0·13 and –54·40 ± 0·10 kcal. mole–1, respectively; NpOCl2(c) in 1M-HCl, –33·64 ± 0·12 kcal. mole–1; NpO3,H2O(c) in 1M-HCl and 1M-HClO4, –12·70 ± 0·10 and –12·85 ± 0·10 kcal. mole–1, respectively. On combination with other thermodynamic data, these results yield the following heats of formation at 298°K. NpIII in 1M-HCl, –126·2 ± 0·2; NpIV in 1M-HCl, –132·3 ± 0·3; NpCl4(c), –236·0 ± 0·3; NpOCl2(c), –245·8 ± 0·3 and NpO3,H2O(c), –332·4, all in kcal. mole–1.Keywords
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