Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions
Journal Article
·
· Soil Science Society of America Journal; (United States)
- Univ. of Tennessee, Knoxville, TN (United States)
In order to increase our understanding of the chemistry of Mo in soil, waste-affected soil, and waste-disposal environments, it is imperative to understand the processes controlling the aqueous and solid-phase distribution of Mo. Recent research shows the importance of alkaline earth metal ion pairs with molybdate in aqueous solutions. However, ion association constants for these species have not been rigorously determined. The objectives of this study were to measure conditional ion association constants (log[sup c]Q) for the formation of Ca and Mg molybdate ion pairs. Potentiometric titrations were performed at pH 7 and 25[degree]C in NaNO[sub 3] ionic media. The log[sup c]Q values were converted to the zero-ionic-strength molar reference state (log Q) using the Davies equation. The mean log Q and standard free energy of formation ([Delta]G[sub f][degrees]) values for the formation of CaMoO[sub 4][sup 0] are 2.57 [plus minus] 0.08 and -1405.19 [plus minus] 1.60 kJ mol[sup [minus]1], respectively. The mean log Q and [Delta]G[sub f][degrees] values for the formation of MgMoO[sub 4][sup 0] are 3.03 [plus minus] 0.13 and [minus]1309.08 [plus minus] 2.06 kJ mol[sup [minus]1], respectively. 14 refs., 2 figs., 1 tab.
- DOE Contract Number:
- FC21-86MC11076
- OSTI ID:
- 5521899
- Journal Information:
- Soil Science Society of America Journal; (United States), Journal Name: Soil Science Society of America Journal; (United States) Vol. 56:4; ISSN 0361-5995; ISSN SSSJD4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540200 -- Environment
Terrestrial-- (1990-)
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHEMISTRY
COMPLEXES
ENERGY
FORMATION FREE ENERGY
FREE ENERGY
LAND POLLUTION
MAGNESIUM COMPOUNDS
MOLYBDATES
MOLYBDENUM COMPOUNDS
MONITORING
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLLUTION
POTENTIOMETRY
REFRACTORY METAL COMPOUNDS
SOIL CHEMISTRY
THERMODYNAMIC PROPERTIES
TITRATION
TRANSITION ELEMENT COMPOUNDS
400201 -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540200 -- Environment
Terrestrial-- (1990-)
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHEMISTRY
COMPLEXES
ENERGY
FORMATION FREE ENERGY
FREE ENERGY
LAND POLLUTION
MAGNESIUM COMPOUNDS
MOLYBDATES
MOLYBDENUM COMPOUNDS
MONITORING
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLLUTION
POTENTIOMETRY
REFRACTORY METAL COMPOUNDS
SOIL CHEMISTRY
THERMODYNAMIC PROPERTIES
TITRATION
TRANSITION ELEMENT COMPOUNDS