The temperature of maximum in density of aqueous solutions of nitrate and ammonium salts: Testing the Madrid-2019 force field.

ABSTRACT

The shift in the temperature of maximum in density (TMD) at room pressure of aqueous solutions of a set of five salts containing NO3- and/or NH4+ groups is studied both through experiments and through molecular dynamics simulations using the Madrid-2019 force field for ions and the TIP4P/2005 model for water. The experiments demonstrate the potential transferability and limitations of the Madrid-2019 force field for nitrate and ammonium ions recently developed by our group at different temperatures and add updated information to the reported datasets of TMDs for strong electrolytes. By using the Despretz law, individual ion contributions are extracted for predictive purposes from the experimental values of the shift in the TMD. Interesting findings for the behavior of the shift in the TMD in nitrate salts expose that this property might be particularly challenging for modelization approaches when dealing with polyatomic species.