Partial molal volumes of some major ions in seawater1

A densimetric method is used for determining the partial molal volumes, V*(i), of NaCl, KCl, CaCl2, MgCl2, Na2SO4, and MgSO4 in seawater and thermal expansibilities of V*(i) of these salts are deduced. A semiempirical relation is proposed for the partial molal volumes of salts, in the range of temperatures and salinities of the world ocean. The partial molal volumes of these ions are estimated on the assumption that the partial molal volume at infinite dilution of proton, V* °(H*), is exact and that the volume of transfer of Cl− from pure water to seawater does not vary with temperature. A convenient equation of partial molal volume of ions as a function of temperature and salinity is given.