The evolution of the alchemical work associated to the intrusion of an electrolyte unit in zeosils filled with water at 200 MPa (chabazite and faujasite) and 400 MPa (silicalite-1) is presented in Figure while row values and error estimation can be found in Tables and. The alchemical work is the lowest in the silicalite-1, and increases for chabazite and faujasite which is consistent with silicalite-1 channel diameter and chabazite and faujasite cage diameter. We deduce that a lower pore size is associated to a mediocre solvation of the ions, because the lack of available space does not allow water molecules to properly form solvation shells around the ions. The alchemical work is lower for every electrolytes investigated compared with ∆µ CnAm (P ) for electrolyte bulk solution at different molalities but it is necessary to be more quantitative by calculating the associated probability for insertion of an electrolyte unit in the zeosils. We recall from our previous work that the probability for accepting an electrolyte unit is written as follows: