Doklady Physical Chemistry

The formation and propagation of cellular combustion of porous media under near-critical combustion existence conditions were investigated. The sizes and structure of cells in which the condensed component reacted with the gas depended nonlinearly on the heat loss to the environment. With increasing heat loss, the oscillation frequency of the cellular front, its average propagation velocity, and the intensity of the exothermic transformation of the condensed phase increased, and the cell sizes decreased. Cellular combustion was extinguished only when the transformation of the condensed component within a cell was completed.

As structural descriptors in chemistry, indices based of information entropy are widely used. The change in information entropy in a chemical reaction is calculated as the difference of the values for the ensemble of products and the ensemble of reactants. In this work, for a generalized scheme of a catalytic reaction, analytical expressions were derived that relate the information entropy change in it with the parameters of individual steps and the corresponding overall equation. It was found that the sum of the parameters of individual steps is proportional to the information entropy change in the formal noncatalytic reaction, and the coefficient of proportionality is the fraction of atoms contained in reacting (forming) molecules of the ensemble of reactants (or products).

The negative pressure (tension) was measured by Raman spectroscopy in an aqueous 2m Na2WO4–CsCl solution during a metastable-to-stable state transition. Phase transitions were observed optically in synthetic fluid inclusions in a single quartz crystal. In the metastable liquid phase, the vapor phase nucleation pressure at 48°C is −105 ± 5 MPa. Water equation of state (IAPWS-95) predicts the nucleation pressure for this density to be approximately −160 MPa.