Refractometry determination of the hydration number of ions in diluted aqueous solutions of magnesium sulfate

Refraction properties of diluted aqueous solutions of magnesium sulfate are studied. In order to explain experimental results, we use the Lorentz-Lorentz equation, where the contributions of both free water molecules and hydrated ions to net polarization are taken into account. The hydration numbers of ions are determined according to both refractometry and an ion-dipole model that we propose.