The specific interaction model has been used to determine the partial molal volume of electrolytes in 0.725 m NaCl and 35‰ salinity seawater solutions at 25°C. The partial molal volumes of electrolytes (MX) were estimated at a given ionic strength (I) from V(MX) = V0(MX) + SvI 1 2 (1 + I 1 2) + vM ∑ XBMX[X] + vX ∑ MBMX[X], where SV is the Debye-Hückel limiting law slope, vi is the number of ions i formed when MX dissociated, [i] is the total molality of ion i and BMX is a specific interaction parameter that varies slowly with ionic strength. The values of V(MX) estimated by using this equation were found to agree very well with experimental values in NaCl and seawater providing there are not strong interactions between M and X. For electrolytes that form ion pairs (i.e. MX°) corrections must be made. Methods are discussed for making these corrections.
ASJC Scopus subject areas
- Geochemistry and Petrology