For the binary mixtures of [Hmim][NO3] with (C6 to C10) 1-alkanol, values of cohesive energy density (ced), free volume (vf ), and internal pressure (Pint) at 303.15 K and ambient pressure were calculated. To calculate the cohesive energy density and the internal pressure of the binary systems, the COSMO-RS model in combination with experimental densities, and Flory’s statistical theory was applied respectively. From the above results, the Pint/ced ratio was tested to study the ‘structuredness’ of fluids. Obtained values (0.2–0.8) are a feature of associated or ionic liquids and demonstrate the strong interactions in binary fluids. The variation of calculated parameters with the chain length of alcohols and the mole fraction of ionic liquid was considered from the standpoint of molecular interactions. It was found that increasing the alkyl chain of alcohol loosens the packing structure of binary liquids and reduces the strength of intermolecular forces
