Vibrational spectral studies of solutions at elevated temperatures and pressures. 8. A Raman spectral study of ammonium hydrogen sulfate solutions and the hydrogen sulfate-sulfate equilibrium
| Autor: | G. E. Toogood, B. S. W. Dawson, D. E. Irish |
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| Rok vydání: | 1986 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 90:334-341 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100274a027 |
| Popis: | Raman spectra of aqueous ammonium hydrogen sulfate solutions spanning a temperature range from 25 to 300 /sup 0/C, at a pressure of 10 MPa, have been measured. The conversion of sulfate to hydrogen sulfate ion is virtually complete at 300 /sup 0/C. The relative integrated intensities of the 980-cm/sup -1/ line of SO/sub 4//sup 2 -/ and the 1040-1050-cm/sup -1/ lines of HSO/sub 4//sup -/ have been measured. The relative integrated molal intensities are almost independent of temperature. From the intensities, the populations of the species SO/sub 4//sup 2 -/ and HSO/sub 4//sup -/ have been calculated and thus the change in the degree of dissociation of the acid with temperature has been measured. The equilibrium constant has been partitioned into two terms - the concentration quotient Q/sub m/ and the activity coefficient quotient Q/sub ..gamma../. The latter changes with temperature much less than the former. The contributions of each to the standard enthalpy change, ..delta..H/sup 0/, have been estimated. The marked shift of the (S-(OH)) vibration of HSO/sub 4//sup -/ to lower frequencies as the temperature rises is linked to the changes in hydrogen bonding resulting from changes in the structure of liquid water and the interaction between watermore » and HSO/sub 4//sup -/. 55 references, 8 figures, 7 tables.« less |
| Databáze: | OpenAIRE |
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