Partial molar volume of water in phonolitic glasses and liquids

Abstract

The volumes and expansivities of four hydrous phonolite glasses and liquids have been measured by dilatometry from 300 K up to the glass transition and over a 50 K interval just above the glass transition. The partial molar volume of water is independent of the water content for the glass and liquid phases, with values of about 11.0±0.5 and 17.1±0.9 cm3/mol at 300 and 800 K, respectively. The partial molar thermal expansivity of water in phonolite glasses is about 8×10–5 K–1, a result similar to recently published values for different silicate compositions, and about 36.5×10–5 K–1 in phonolite liquids. The implications for melt density and water dissolution are discussed.