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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



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, VSiO2 = 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 K3FMoO4, 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)

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