ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Density of Melts of the System KF—K₂MoO₄—SiO₂

M. Chrenková, M. Boča, M. Kuchárik, and V. Daněk

Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-842 36 Bratislava

E-mail: uachchr@savba.sk

Received: 10 April 2002

Abstract: The density of the melts of the system KF—K₂MoO₄—SiO₂ was measured using the Archimedean method. On the basis of the obtained density data the molar volume, partial molar volume, and excess molar volume of the melts were calculated in order to consider the possible chemical interactions of components. In the system KF—K₂MoO₄ the density increases monotonically with increasing content of K₂MoO₄. The formation of the additive compound K₃FMoO₄ causes only small positive deviations from the ideal behaviour. In the system KF—SiO₂ the density increases with increasing content of SiO₂. The partial molar volume of SiO₂ in the melt is a little higher than that of the pure SiO2, which may refer to some weak chemical interaction of both components leading to a small volume expansion. The density of the system K₂MoO₄—SiO₂ increases with increasing content of SiO₂. The partial molar volume of SiO₂ in the infinitely diluted solution, V_SiO2 = 3.65 cm³ mol⁻¹, may refer to a strong chemical interaction of both components accompanied by a substantial volume contraction. Two different regions are present in the investigated part of the system KF—K₂MoO₄—SiO₂. In the region of low content of SiO₂, near the figurative point of K₃FMoO_4, there is a region of volume expansion, while at higher SiO2 concentration a region of volume contraction is present. The volume expansion is caused by the formation of the additive compound K₃FMoO₄, while the volume contraction refers probably to the formation of the heteropolyanions [SiMo₁₂O₄₀]⁴⁻.

Full paper in Portable Document Format: 565a283.pdf

Chemical Papers 56 (5) 283–287 (2002)