Gas Combustion Reaction Mechanism
A: Classical chemical kinetics starts from the molecular point of view and uses chemical reaction equations to study chemical reactions
B: However, experiments have shown that the mechanism of most chemical reactions is very complicated. They do not obtain products from reactants in one step according to the reaction equation, but go through complex intermediate processes to produce various intermediate active products ( or activation center), step by step.
C: The distribution of matter energy between molecules is always uneven, and there are always some unstable molecules. These unstable molecules in the substances participating in the reaction constantly become chemically very active particles-activation centers during the collision process. Most of these active centers are unstable free atoms and free radicals.
D: The activation energy of the interaction between the activation center and the stable molecule is small, so that the chemical reaction avoids high-energy obstacles. Therefore, it is much easier to react through the activation center than to react directly with the original reactants.
E: Through the reaction between the activation center and the stable molecule, new intermediate active products will continue to be formed, just like a chain, which develops successively one after another to keep the reaction going until the reactants are exhausted or through external factor that breaks the chain link
F: During the combustion reaction, each chain has two or more activation centers that can lead to new chains, chain branches, and a sharp increase in the reaction rate. This chain reaction is called a branched chain reaction
G: Once caught fire, the combustion reaction has the characteristics of continuous branching and automatic acceleration.
H: The process of combustion reaction is very complicated, people only understand the simplest reaction mechanism of hydrogen and oxygen 2H, +O, = 2H,0
I: According to the molecular thermal activation theory, the possibility of three stable molecules colliding and reacting at the same time is very small
J: Experiments have shown that in the mixed gas of hydrogen and oxygen, there are some unstable molecules, which constantly become chemically active free atoms and free radicals-activation centers (H, O, OH groups) during the collision process . It is much easier to react through the activation of the chemical courseware resource center than the original reactant.