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Chemical Kinetics
Published in Achintya Mukhopadhyay, Swarnendu Sen, Fundamentals of Combustion Engineering, 2019
Achintya Mukhopadhyay, Swarnendu Sen
The collision theory of reaction rates states that the reaction rate is equal to the number of collisions per unit time between molecules having collision energy above a threshold value (activation energy). The major assumptions are as follows: Collision energy needed for molecular change is derived from the relative translation energy of colliding molecules.Gas is sufficiently dilute that only binary collisions are important.Equilibrium Maxwell velocity distribution can be used even though the chemical reaction is highly transient.
Chemical Reaction Optimization
Published in Nazmul Siddique, Hojjat Adeli, Nature-Inspired Computing, 2017
The most important part of the reaction mechanism is the energy requirements, where energy is consumed for a reaction to happen. The actual course that any reaction should follow is the one that requires least activation energy. The minimum amount of energy required for a chemical reaction to occur is known as the activation energy denoted as Ea, discussed in the earlier section. For a reaction to occur, molecules must collide. The collision frequency describes how many times a particular molecule collides with others per unit of time. Collision theory is an aspect of kinetic molecular theory and was proposed by Max Trautz (1916), which explains how chemical reactions occur and why reaction rates differ for different reactions. In order for molecules to react, a physical chemist named Svante Arrhenius explained in 1889 (Arrhenius, 1889) that colliding molecules must possess enough kinetic energy. Energetic collisions are collisions between molecules with enough kinetic energy to cause the reaction to occur. Not all collisions are energetic collisions because they do not provide the necessary amount of Ea, so not all collisions lead to reactions and product formation. The higher the Ea of a reaction, the smaller is the amount of energetic collisions present, and the slower is the reaction. In contrast, the lower the Ea of a reaction, the greater is the amount of energetic collisions present, and the faster is the reaction. The molecular orientation of the energetic collision has to be right to generate the activated complex in the transition state that leads to the product.
Principles of Chemistry
Published in Arthur T. Johnson, Biology for Engineers, 2019
Before two compounds can react chemically, they must contact each other. Collision theory has been formulated to explain various factors on chemical reaction rates. Part of this theory is the Law of Mass Action, which states that a chemical reaction will occur at a rate proportional to the concentration of its reactants. Thus, anything that can be done to concentrate reaction precursors in the presence of each other will favor the desired chemical combination to occur.
Experimental and statistical optimization of the hydrogen reduction process of nickel oxide
Published in Materials and Manufacturing Processes, 2018
Maryam Abdollahi, Mahmood Sameezadeh, Majid Vaseghi
Another conclusion from Fig. 4 is that simultaneous increase of hydrogen gas flow and holding time has enhanced the NiO conversion process from S1 to S2 and S3. When a reaction is performed at high temperatures, more energy is entered into the system, and this increases the collisions between particles, thus, according to collision theory, the reaction rate during the process will be increased. So, the basic reason for increasing the hydrogen reduction rate by increasing temperature is that the colliding particles will have needful activation energy after successful collisions[24]. Certainly mutual role of reaction parameters alongside each other was different from the individual role of each parameter.
Effectively remove printing ink from plastic surface over quaternary ammonium-modified waste cooking oil
Published in Environmental Technology, 2023
Xiaoxia Ye, Zhihao Wu, Min Wang, Yuancai Lv, Xiaodan Huang, Yifan Liu, Chunxiang Lin
According to the collision theory of chemical reaction rate [39], when the temperature is raised or the concentration of reactants is increased, the number of reactive activated molecules increases, and the number of effective collisions increases and the reaction rate accelerates. The longer the pre-soaked time, the lower the adhesive force between the ink molecules and the plastic, the more conducive to the removal of the ink, the pre-soaking is conducive to the subsequent stripping of the ink, which can effectively reduce the mechanical energy consumption.
Example of removing printing ink from plastic surface using quaternary ammonium-modified waste cooking oil
Published in Environmental Technology, 2023
Xiaoxia Ye, Zhihao Wu, Min Wang, Yuancai Lv, Xiaodan Huang, Yifan Liu, Chunxiang Lin
According to the collision theory of chemical reaction rate [39], when the temperature is raised or the concentration of reactants is increased, the number of reactive activated molecules increases, and the number of effective collisions increases and the reaction rate accelerates. The longer the pre-soaked time, the lower the adhesive force between the ink molecules and the plastic, the more conducive to the removal of the ink, the pre-soaking is conducive to the subsequent stripping of the ink, which can effectively reduce the mechanical energy consumption.