Abstract
Pure and well crystallised whitlockite Ca18Mg2H2(PO4)14 has been synthesized by precipitation from the magnesium and calcium nitrates and the diammonic phosphate. The product of the reaction has been characterized by X-ray diffraction, IR spectroscopy and chemical analysis. Using differential conduction calorimeters the enthalpies of solution of the whitlockite and of a mixture of the solid reactants - the tricalcium, the trimagnesium and the dicalcium phosphates - have been measured at 25°C for various concentrations of solid in a 46 wt% nitric acid solution. A combination of the enthalpies of solution with the enthalpies of formation of the reactants allows us to determine the standard enthalpy of formation of the whitlockite. The value deduced, -27,93·103kJ mol-1, is compared to the standard enthalpies of formation of the trimagnesium and the tricalcium phosphates.
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Références
S. Ben Abdelkader, I. Khattech, C. Rey and M. Jemal, Thermochim. Acta, 376 (2001) 25.
R. Z. Legeros, Tooth Enamel IV, Ed. par R. W. Fearnhead et S. Sugas, Elsevier, 1984, pp. 32–6.
E. R. Kreidler and F. A. Hummel, Am. Mineral., 55 (1970) 170, cité par J. C. Elliott, Studies in Inorganic Chemistry, Elsevier 1994.
M. H. Salimi, J. C. Heughebaert et G. H. Nancollas, Langmuir, 1 (1985) 119, cité par la réf. 13.
M. Hamad et J. C. Heughebaert, J. Chim. Phys., 84 (1987) 985.
E. Hayek et H. Newsely, Mn. Chem., 89 (1958) 88, cité par la réf. 5.
S. L. Rowles, Bull. Soc. Chim. Fr., (1968) 1797, cité par la réf. 5.
K. S. Gavritchev, G. A. Sharpataya, A. A. Smagin, E. N. Malyi and V. A. Matyukha, J. Therm. Anal. Cal., 73 (2003) 71.
C. Marhag, H. Saud, P. Satre, C. Favotto and J. Rogez, J. Therm. Anal. Cal., 74 (2003) 275.
L. Zhihong, H. Mancheng and G. Shiyang, J. Therm. Anal. Cal., 75 (2004) 73.
A. Ben Cherifa, B. Omezzine and M. Jemal, J. Soc. Chim. Tun., 11 (1984) 53.
A. Ben Cherifa and M. Jemal, Ann. Chim. Fr., 10 (1985) 543.
M. Hamad, Th_se de Doctorat, I. N. P., Toulouse 1987.
Fichier ASTM n°13-404: (Ca, Mg)3(PO4)2, whitlockite.
A. Gee et V. R. Deitz, Ann. Chim. Fr., 25 (1953) 1320.
M. Hamad and J. C. Heughebaert, J. Cryst. Growth, 79 (1986) 192.
R. Gopal and C. Calvo, Can. J. Chem., 52 (1974) 1155, cité par la réf. 5.
C. Calvoc and R. Gopal, Am. Miner., 60 (1975) 120, cité par la réf. 10.
S. Ben Abdelkader, A. Ben Cherifa, I. Khattech and M. Jemal, Thermochim. Acta., 334 (1999) 123.
M. Ganteaume, M. Coten and M. Decressac, Thermochim. Acta, 178 (1991) 81.
W. J. Guedens, J. Yperman, J. Mullens, L. C. Van Poucke and E. J. Pauwels, J. Chem. Educ., 70 (1993) 776.
V. B. Parker, D. D. Wagman and W. H. Evans, Selected values of chemical thermodynamic properties, Technical note 270–6, NBS circular 500, US Department of Commerce (1971).
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Ben Abdelkader, S., Ben Cherifa, A., Coulet, M.V. et al. Enthalpie de formation de la whitlockite Ca18Mg2H2(PO4)14 . Journal of Thermal Analysis and Calorimetry 77, 863–871 (2004). https://doi.org/10.1023/B:JTAN.0000041665.41225.c3
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DOI: https://doi.org/10.1023/B:JTAN.0000041665.41225.c3