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The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
[4] [5] [6] The CALPHAD approach is based on the fact that a phase diagram is a manifestation of the equilibrium thermodynamic properties of the system, which are the sum of the properties of the individual phases. [7] It is thus possible to calculate a phase diagram by first assessing the thermodynamic properties of all the phases in a system.
The kinetic derivation applies to gas-phase adsorption. However, it has been mistakenly applied to solutions. The multiple-adsorbate case is covered in the competitive adsorption sub-section. The model assumes adsorption and desorption as being elementary processes, where the rate of adsorption r ad and the rate of desorption r d are given by
Though the gas adsorbed on these surfaces may consist of a layer only one or at most a few molecules thickness, surface areas of several hundred square meters per gram enable the adsorption of a large portion of the adsorbent's weight in gas. In addition to their affinity for different gases, zeolites and some types of activated carbon may ...
The phase diagram shows, in pressure–temperature space, the lines of equilibrium or phase boundaries between the three phases of solid, liquid, and gas. The curves on the phase diagram show the points where the free energy (and other derived properties) becomes non-analytic: their derivatives with respect to the coordinates (temperature and ...
For a condensed-phase (e.g., solution-phase) or unimolecular gas-phase reaction step, E a = ΔH ‡ + RT. For other gas-phase reactions, E a = ΔH ‡ + (1 − Δn ‡)RT, where Δn ‡ is the change in the number of molecules on forming the transition state. [15] (Thus, for a bimolecular gas-phase process, E a = ΔH ‡ + 2RT.)
Electron affinity can be defined in two equivalent ways. First, as the energy that is released by adding an electron to an isolated gaseous atom. The second (reverse) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion.
A three-component compatibility diagram will depict the stable phase of each pure component as the point at each corner of a ternary diagram. Additional points in the diagram represent other pure phases, and lines connecting pairs of these points represent compositions at which the two phases are the only phases present.