Explosivity Conditions of Aqueous Solutions

This paper focuses on the conditions for explosive boiling and gas exsolution of aqueous solutions from a thermodynamic point of view. Indeed, the kinetic nature of these processes, hence their explosivity, can be assessed by considering their relation with the spinodal curve of these liquids. First, the concepts of mechanical and diffusion spinodals are briefly described, which allows us to introduce the notions of superspinodal (explosive) transformations and subspinodal (non-explosive) ones. Then, a quantitative study of spinodal curves is attempted for the binary systems H₂O–CO₂ and H₂O–NaCl using equations of state having a strong physical basis. It is shown that dissolved gaseous components and electrolytes have an antagonist effect: dissolved volatiles (like CO₂) tend to shift the superspinodal region towards lower temperatures, whereas electrolytes (like NaCl) tend to extend the metastable field towards higher temperatures.