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Reactances of synchronous machines. The reactances of synchronous machines comprise a set of characteristic constants used in the theory of synchronous machines. [1] Technically, these constants are specified in units of the electrical reactance (ohms), although they are typically expressed in the per-unit system and thus dimensionless.
Energy profile (chemistry) In theoretical chemistry, an energy profile is a theoretical representation of a chemical reaction or process as a single energetic pathway as the reactants are transformed into products. This pathway runs along the reaction coordinate, which is a parametric curve that follows the pathway of the reaction and indicates ...
It offers a concrete interpretation of the pre-exponential factor A in the Arrhenius equation; for a unimolecular, single-step process, the rough equivalence A = (k B T/h) exp(1 + ΔS ‡ /R) (or A = (k B T/h) exp(2 + ΔS ‡ /R) for bimolecular gas-phase reactions) holds. For a unimolecular process, a negative value indicates a more ordered ...
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. [1] A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction. The detailed steps of a reaction are not observable in most cases ...
This has the same form as an equation for a straight line: = +, where x is the reciprocal of T. So, when a reaction has a rate constant obeying the Arrhenius equation, a plot of ln k versus T −1 gives a straight line, whose slope and intercept can be used to determine E a and A respectively. This procedure is common in experimental chemical ...
The standard model is a quantum field theory, meaning its fundamental objects are quantum fields, which are defined at all points in spacetime. QFT treats particles as excited states (also called quanta) of their underlying quantum fields, which are more fundamental than the particles. These fields are.
Energy diagrams showing how to interpret Hammond's Postulate. In case (a), which is an exothermic reaction, the energy of the transition state is closer in energy to that of the reactant than that of the intermediate or the product. Therefore, from the postulate, the structure of the transition state also more closely resembles that of the ...
For a catalyzed reaction, the activation energy is lower. In chemistry, a reaction coordinate[1] is an abstract one-dimensional coordinate chosen to represent progress along a reaction pathway. Where possible it is usually a geometric parameter that changes during the conversion of one or more molecular entities, such as bond length or bond angle.