Study of Ionic Interactions in Solution and Influence of Alkyl Chain Cation – Solvent on Water Structure in Ethanol – Water Mixture by Magnetic Float Densitometer

The densities of the binary solvent mixtures and its salt solutions have been measured by one of the recently modified techniques, namely Magnetic Float Densitometer. The partial molar volume or apparent molar volume ϕv and at infinite dilution are determined by ϕv0 values of solution mixtures for some tetra alkyl ammonium iodide salts from aqueous to non aqueous binary solvent mixture of Water – Ethanol system. The ϕv values showed positive and large for all the tetra alky ammonium salts in all the compositions of binary mixture solution. This is due to, the presence of weak ion- ion interactions between the components of the mixtures. The value of ϕv increases on decreasing the concentration of ethanol. The value of slope Sv also showed positive for Et4NI and Pr4NI salt solution whereas it is negative for Bu4NI and Pen4NI salts solution. This is due to the presence of specific molecular interactions that will lead to increase in electrostriction with the presence of water in the solution mixture.