Densities of liquid H+/NH4+/SO42-/NO3-/H2O solutions at tropospheric temperatures

Densities of liquid aqueous solutions of the system H+/NH4+/SO42-/NO3-/H2O have been determined experimentally at temperatures between 243 and 353 K for total solute mass fractions up to 0.6. The new density data, together with additional data from the literature, have been evaluated using a semi-empirical model that is based on a partial molar volume approach. With this model densities of multicomponent solutions can be predicted from parameters determined from binary solutions of the corresponding solutes. Model predictions for ternary or quaternary solutions agree with experimental data to about one percent. The advantages of our approach are that the model can be extended to include additional solutes without a re-parameterization of the existing binary parameters, and that it allows extrapolation to temperatures of the upper troposphere and lower stratosphere.