Standard reference material proposed for enthalpy-of-sublimation measurements. A comparative study of the standard molar enthalpy of sublimation of Fe(c-C5H5)2(ferrocene) by calorimetry and knudsen-effusion techniques
✍ Scribed by Luis Alfonso Torres; Ramón Gudiño; Raphaël Sabbah; Juan Antonio Guardado
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 350 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0021-9614
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✦ Synopsis
The standard molar enthalpy of sublimation of Fe(c-C5H5)2,bis(h-cyclopentadienyl)iron(II), ferrocene, has been experimentally determined by the Knudsen-effusion method using a quartz-crystal microbalance. The results from two series of experiments were found to be DsubH°m(298.15 K)=(74.3420.41) kJ•mol -1 and DsubH°m(280.74 K)=(74.6020.79) kJ•mol -1 . This property has also been calorimetrically determined at the temperature T=298.15 K, and the mean value from 12 experiments were found to be DsubH°m=(73.1920.66) kJ•mol -1 . All the literature results for the standard molar enthalpy of sublimation reported to date which have been determined by indirect methods were critically evaluated, and the more reliable values retained. A global analysis including these selected values as well as our effusion and calorimetric results leads to a weighted average value of DsubH°m=(73.4220.59) kJ•mol -1 for the standard molar enthalpy of sublimation of Fe(c-C5H5)2 at T=298.15 K. From this study we propose the use of ferrocene as a standard reference material for measurements of enthalpy of sublimation.