Solvation of Na+ with water.
We discussed earlier how the general idea of capacitance was a useful conceptual tool for interpreting the energy of charge distributions at the molecular level. In fact, dielectrics behave during chemical processes in the same way that they behave between capacitor plates.
Similarly to how the dielectric between the plates of a capacitor reduces the voltage between the plates, the dielectric effect of water decreases the work required to separate the anions and cations of an electrolyte solute as it dissolves.
Because the field between them is weaker with the interposition of a dielectric solvent, such as water, the separation of anions and cations of a dissolving electrolyte now occur at lower energy. The aqueous solvent weakens the electric field between the separating charges.