Thermodynamics of Extremely Diluted Aqueous Solutions
Vittorio Elia, Marcella Niccoli
Department of Chemistry, University "Federico II" of Naples, Via Mezzocannone 4, 80134 Naples, Italy
Annals of the New York Academy of Sciences, 1999, 827:241-248.
An extensive thermodynamic study has been carried out on aqueous solutions ob- tained through successive dilutions and succussions of 1% wt/vol of some solutes up to extremely diluted solutions, (less than l ? 10?5 mol kg?1 ) obtained via several 1/ 100 successive dilution processes. The interaction of acids or bases with the ex- tremely diluted solutions has been studied calorimetrically at 25°C. Measurements have been performed of the heat produced by the mixing of acid or basic solutions of different concentrations, with bidistilled water or with the extremely diluted so- lutions. Despite the extreme dilution of the solutions, an exothermic heat of mixing in excess has been found in about the 92% of the cases, compared to the correspond- ing heat of mixing with the untreated solvent. Here, we show that successive dilu- tions and succussions may permanently alter the physical–chemical properties of the solvent water. The nature of the phenomenon here described still remains unex- plained, but significant experimental results are obtained.