What is Activation Energy?
Activation energy refers to the energy required for a molecule to change from a normal state to an active state prone to chemical reactions. (The activation energy in the Arrhenius formula is different from the activation energy derived from kinetics, also known as Arrhenius activation energy or empirical activation energy).
activation energy
- Chinese name
- activation energy
- Foreign name
- Activation energy
- Also known as
- Threshold energy
- Subject
- Chemistry
- Activation energy refers to the energy required for a molecule to change from a normal state to an active state prone to chemical reactions. (The activation energy in the Arrhenius formula is different from the activation energy derived from kinetics, also known as Arrhenius activation energy or empirical activation energy).
- Activation energy is a chemical term, also known as threshold energy. This term is made up of
- Activation energy is
- Activation energy of chemical reaction
- Experiments have shown that only the energy of the collision molecule is equal to or exceeds a certain energy Ec (can be called
- Arrhenius formula
- The energy absorbed by the non-activated molecules to be converted into activated molecules can be calculated using the Arrhenius equation. The Arrhenius equation reflects the relationship between the chemical reaction rate constant K and temperature. In most cases, its quantitative rule can be determined by
- A. Arrhenius found that there is a relationship d (lnk) / dt = E / RT2 between the constant k of the chemical reaction and the absolute temperature T. Here E is the activation energy. If the above formula is integrated to obtain lnk = lnA- (E / RT), it can be known from this formula that the k value is obtained at various temperatures and the lnk is plotted against 1 / T (this figure is called the Arrhenius diagram ) To obtain a straight line. Since the slope of the straight line is -E / R, the E value can be obtained.
- The physical meaning of activation energy is generally considered as follows: There is a transition state from the original reaction system to the product. The energy difference between this transition state and the original system is the activation energy E, and if the thermal energy RT is not greater than E, the reaction cannot proceed. . That is, there is an energy barrier between the original system and the product system, and its height is equivalent to the activation energy. H. Eyring then proceeded from the approximate equilibrium between the transition state (also called the active complex) and the original system, and derived the following relationship for the velocity constant k: k = k (KT / h) exp (-G * / RT) = k (KT / h) exp (S * / R) exp (-H * / RT) k is the permeability coefficient, K is the Boltzmann constant, and h is the Planck constant , G *, S *, H * are the activation free energy, activation entropy, and activation enthalpy, respectively. Moreover, the activation free energy is approximately equal to the activation enthalpy. The enzymatic reaction is mainly due to the reduction of the free energy of activation.