Un modello semplificato della struttura dell'acqua

Ageno, Mario

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 46 (1969) no. 4, pp. 427-435

Résumé

A Simplified Model for the Structure of Water. The collective model of the hydrogen bond proposed by the Author two years ago is used as a starting point for developing a model for the structure of water in which only linear chains of molecules are considered. Other types of aggregates, even if in agreement withthe collective model, are disregarded. Only one equilibrium constant K is introduced to take into account all the different reactions between polymers in the liquid, and the concentration of each type of polymer is calculated. The mean number L of molecules per polymer is deduced and from the values of L derived from experiments presented in a previous paper, the dependence on temperature of K is obtained. The graph of log K plotted against 1/T is strictly linear while the energy of the hydrogen bond in the liquid is 0.11 ev. The variation in the chemical shift of water protons is examined. According to the model, three different types of protons exist in the liquid, the molar fraction of which can be calculated in terms of L. The observable chemical shift of water protons is then calculated at various temperatures in the case of rapid exchange, and the result agrees very well with the measurements of Hindman.