activation energy

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ac·ti·va·tion energy

The least amount of energy needed for a chemical reaction to occur. For example, striking a match on the side of a matchbox provides the activation energy, in the form of heat, necessary for the chemicals in the match to catch fire.
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Noun1.activation energy - the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur; "catalysts are said to reduce the energy of activation during the transition phase of a reaction"
energy, free energy - (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs; "energy can take a wide variety of forms"
aktivacijska energija
References in periodicals archive ?
Hayward said that the mechanics that explain the ability of corrugated tubes to be extended and contracted in length are "pretty well established," as is the idea that moving materials between mechanically stable states require overcoming an energy barrier. Playing with a variety of colorful bendable tubes on his desk, he demonstrates that the tube holds its shape in either state and that an energy barrier is crossed when it pops in and out of each.
In another study, Fancey [18] proposed a stress relaxation function based on an Eyring potential energy barrier model [19].
The [Nb.sub.2][O.sub.5] has the capacity to minimizing effects of charge recombination by the formation of an energy barrier due your band gap is larger when compared the other semiconductors [10].
As it is seen in Figure 1, the reaction along the low-multiplicity channel can evolve to the sulfide oxide SV[O.sub.2] after surmounting a relatively small energy barrier of 23.3 kcal/mol.
Channel (5) has the lowest energy barrier (32.8 kcal/mol) and the lowest energy of [P.sub.2]HNCO + [C.sub.2][H.sub.4] (-72.9 kcal/mol).
From Equation (1), the [beta] to [alpha] phase transformation can only proceed when the driving force (V[DELTA][G.sub.V] + [DELTA][G.sub.d]) is large than the activation energy barrier (A[gamma] + V[DELTA][G.sub.s]).
The coming union of the Disney and Fox media empires is set to create a new nirvana for fanboys and -girls, one that reunites superheroes and sci-fi characters long separated by an energy barrier of corporate legalism.
This class has the ability to deploy an energy barrier that can be used as cover.
It has been found that the energy barrier for the direct cracking of these pyridinic rings is about 600 kJ/mol and that the conversion starts at a temperature of 700 [degrees]C and becomes more intensive at 1200 [degrees]C.
In the paper, lead author Won-Hee Ryu, a former postdoctoral researcher in Taylor's lab, noted that the molecule would dissolve into the battery's electrolytes and act as a redox mediator, which lowers the energy barrier required for the electrochemical reaction to take place.
The rate of change of the depletion width and energy barrier height with temperature in accordance with the linear fitting of the data (shown by solid lines in Figure 3) are [w.sub.o] = 0.037T - 10.20 ([micro]m) and [[phi].sub.o] (T) = 7.08 x [10.sup.-4] T + 0.68 (eV).
Q is the diffusion activation energy, that is, the highest energy barrier for the impurity atoms to diffuse from one most stable vacancy to another [5].