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The DHCP (double hexagonal close-packed) form β-cerium is the equilibrium structure approximately from room temperature to −150 °C. The fcc form α-cerium is stable below about −150 °C; it has a density of 8.16 g/cm 3. Other solid phases occurring only at high pressures are shown on the phase diagram.
A stirred BZ reaction mixture showing changes in color over time. The discovery of the phenomenon is credited to Boris Belousov.In 1951, while trying to find the non-organic analog to the Krebs cycle, he noted that in a mix of potassium bromate, cerium(IV) sulfate, malonic acid, and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions ...
The main disadvantage of the stoichiometric ceria cycle lies in the fact that the reduction reaction temperature of cerium(IV) oxide is at the same range of the melting temperature (1,687–2,230 °C) of cerium(IV) oxide (), [5] which in the end results in some melting and sublimation of the material, which can produce reactor failures such as ...
In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve. One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist.
Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H –pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system.
Cerium nitrates also form 4:3 and 1:1 complexes with 18-crown-6 (the ratio referring to that between cerium and the crown ether). Classically CAN is a primary standard for quantitative analysis. [6] [7] Cerium(IV) salts, especially cerium(IV) sulfate, are often used as standard reagents for volumetric analysis in cerimetric titrations. [8]
Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO 2. It is an important commercial product and an intermediate in the purification of the element from the ores.
Chemical systems cannot oscillate about a position of final equilibrium because such an oscillation would violate the second law of thermodynamics.For a thermodynamic system which is not at equilibrium, this law requires that the system approach equilibrium and not recede from it.