Chemical reaction equation - conditional record of a chemical reaction

2024 Author: Angel Austin | [email protected]. Last modified: 2024-01-02 17:39

To simplify the recording of chemical processes and their better perception, the reaction equation is used. It is a conditional record of the interaction of substances with each other and, as a result, the formation of new products. With such a schematic "image", in order to comply with the law of conservation of the mass of matter, numerical coefficients are used. Such a description of chemical reactions using numbers and symbols was proposed in 1615 by Jean Begun. Later, after the discovery of the laws of stoichiometry, quantitative values began to be used.

The chemical reaction equation is written as follows:

1. On the left side of the schematic "image" there are substances between which the interaction takes place, a "+" sign is placed between them. On the left side are the reaction products, i.e. new compounds that are formed. An arrow is placed between the left and right parts, indicating the direction of the reaction. For example, C+E → SE.
2. Then the coefficients are placed, the task of which is to “equalize”, i.e. make sure that the number of each type of atom before the reaction is equal to the number of atoms after it. This is how the law of conservation of mass works. For example, 2HCl – H₂+Cl_2.

There is a kinetic reaction equation that expresses the dependence of the rate of a chemical process on the concentration of substances that have entered into interaction. A simple such reaction going in one stage is schematically written as follows: V=k[A₁] n¹ [A₂]n^{2 where}

V – reaction rate;

[A₁], [A_{2] – substance concentrations;}

K – reaction rate constant, which depends on the nature of the interacting substances and temperature;

¹, n2 – reaction order.

If the reaction goes in several stages, then they make up a system of kinetic equations, each of which will be described separately.

Also, a separate type is the ionic equation of the reaction, which, when compiled, has features, because the substances recorded in it are in the form of ions. Such a schematic representation of a chemical interaction is typical only for substitution and exchange reactions, in aqueous solutions or alloys, during which a precipitate is formed, poorly dissociating substances (water) or gas is released. For example: hydrochloric acid and potassium hydroxide react chemically to form s alt and water.

HCl + KOH– KCl + H_2O

We write these substances in the form of ions, with the exception of water, because. it does not dissociate. Such an equationreactions will be called complete ionic.

H⁺ + Cl^- + C⁺+ OH ^- --K⁺+Cl^-+H_2O

Now in this scheme, according to the principle of similarity, we “reduce” the repeating ions on the right and left sides and get:

N⁺ + OH^- -- N_2O.

Also, redox reactions, characterized by a change in the oxidation states of atoms, will have features in the preparation of a schematic record. It is necessary to determine the atoms that have changed the oxidation state, and draw up an electronic balance, on the basis of which then arrange the coefficients.

Thus, the chemical reaction equation is a schematic record of the entire complex process of formation of new substances through decomposition, combination, substitution and exchange. It also provides qualitative and quantitative information about reactants and reaction products.