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In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical or physical state, with the defining characteristic being that this resultant state exhibits an increased propensity to undergo a specified chemical reaction.
The activation energy is the minimum amount of energy to initiate a chemical reaction and form the activated complex. [6] The energy serves as a threshold that reactant molecules must surpass to overcome the energy barrier and transition into the activated complex.
In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. [1] The activation energy ( E a ) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). [ 2 ]
These so-called activation parameters give insight into the nature of a transition state, including energy content and degree of order, compared to the starting materials and has become a standard tool for elucidation of reaction mechanisms in physical organic chemistry. The free energy of activation, ΔG ‡, is defined in transition state ...
In organic chemistry and organometallic chemistry, carbon–hydrogen bond activation (C−H activation) is a type of organic reaction in which a carbon–hydrogen bond is cleaved and replaced with a C−X bond (X ≠ H is typically a main group element, like carbon, oxygen, or nitrogen).
Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents.
Activated carbon. Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that greatly increase the surface area [1] [2] available for adsorption or chemical reactions. [3]
The activation overpotential is the potential difference above the equilibrium value required to produce a current that depends on the activation energy of the redox event. While ambiguous, "activation overpotential" often refers exclusively to the activation energy necessary to transfer an electron from an electrode to an anolyte.