Apparent Molar Volumes of Aqueous Solutions of Magnesium Tetraborate from 283.15 to 363.15 K and 0.1 MPa

Densities for aqueous solutions of magnesium tetraborate MgB4O7(aq) at the molalities of (0.00556-0.03341) mol center dot kg(-1) were measured with an Anton Paar Digital vibrating-tube densimeter at temperature intervals of 5 K from 283.15 to 363.15 K and 0.1 MPa. Apparent molar volumes were obtained based on the experimental density data, and the 3D diagrams of the apparent molar volume (V (I center dot) ) of MgB4O7(aq) against temperature (T) and molality (m) were plotted. On the basis of the Vogel-Tamman-Fulcher equation, the coefficients of the correlation equation for densities of MgB4O7(aq) against temperature and molality were parameterized. According to the Pitzer ion-interaction model of the apparent molar volume, the temperature correlation equations of Pitzer single-salt parameters F(i,p,T) = a (0) + a (1) x T + a (2) x T (2) + a (3)/T + a (4) x ln(T) + a (5) x T (3) (where T is temperature in Kelvin, a (i) are model parameters) for MgB4O7 were obtained for the first time.