The sign of the reaction volume for the water/silica reaction

In the present report, we deal with the question whether the equilibrium of the silica/water reaction shifts under tensile stresses to an increased or reduced hydroxyl concentration or equivalently, which sign the reaction volume shows. From our analysis on the basis of the Le Chatelier-Braun Theorem, it can be concluded that the equilibrium constant of the watersilica
reaction is enhanced due to tensile stresses and that the reaction volume change is positive. In additon it will be shown that the apparently found enlarged water solubility under compressive stresses by Nogami and Tomozawa [2] is an artifact of the stress-dependent diffusivity.