At room temperature, the addition of alkali chlorides to water causes a decrease in the benzene solubility. This salting out effect is studied by calculating the reversible work of cavity creation in hard sphere mixtures with the scaled particle theory formula and the reversible work of turning on benzene-solvent attractive interactions. This approach, notwithstanding its simplicity, is able to provide a rationalization of experimental data, showing that two geometric features of aqueous salt solutions, the volume packing density and the average value of the effective hard sphere diameter, are the main determinants of benzene solubility.