Definition of chemical reaction limit, can chemical reaction limit be changed

Chemical reaction. Limit 1, Concept: The limit of a chemical reaction is the maximum amount that can be achieved by studying a reversible reaction.

2. Reversible reaction: under the same reaction conditions, it can be carried out in both the positive and reverse reaction directions. 3. Description:

1) The vast majority of reactions have some degree of reversibility. A reaction is necessary for a reversible reaction: it takes place under the same reaction conditions.

2) When the reversible reaction is carried out to a certain extent under certain conditions, the positive reaction rate.

and the rate of the reverse reaction is equal, the concentration of reactants and products does not change, and the amount of the substance produced per unit time.

Equal to the amount of this substance consumed, the reaction reaches chemical equilibrium.

State. (3) Chemical equilibrium is a dynamic equilibrium. In the state of chemical equilibrium, the chemical reaction is still carried out, but the composition of the reaction mixture is consistent, and when the reaction conditions change, the original chemical equilibrium state is destroyed, and a new equilibrium is reached after some time.

OK. The limit is to reach a state of equilibrium, and when external conditions change, the equilibrium can be moved. The limit of a chemical reaction is affected by factors such as temperature, concentration, pressure (with the participation of gas), and the limit of a reversible reaction that has reached the limit will be changed if the above conditions are changed.

Reversible reaction characteristics

1.The reaction cannot be carried out to the end. No matter how long a reversible reaction is underway, it is impossible to convert all reactants to products 100%;

2.Reversible reactions must be reactions that can be converted into each other under the same conditions, such as sulfur dioxide and oxygen under the condition of catalyst and heating to generate sulfur trioxide; The sulfur trioxamine can be decomposed into sulfur dioxide and oxygen under the same conditions;

3.In an ideal reversible process, there is no friction, resistance, hysteresis and other resistances, so there is no loss of active work;

4.reactions that occur at the same time;

5.increase and decrease at the same time;

6.When writing the chemical equation of a reversible reaction, it is represented by a double arrow, and the mutual loss of the substances on both sides of the arrow is the reactant and the product. The left-to-right reaction is usually referred to as a positive reaction, and the right-to-left reaction is called an inverse reaction;

7.Two chemical reactions in a reversible reaction are carried out in opposite directions at the same time under the same conditions, and the two chemical reactions constitute an opposing unity. Two chemical reactions that can be carried out in opposite directions under different conditions cannot be called reversible reactions.

There are two main problems in the use of chemical reactions in the practice of cavity withering, one is to understand the direction and maximum extent of the reaction and the influence of external conditions on the equilibrium, and the other is to know the rate of the reaction and the process and mechanism of the reaction. The former is related to the study of chemical thermodynamics, and the latter is to the study of chemical kinetics. Thermodynamics can only predict the likelihood of a reaction occurring under a given condition, whether the reaction can occur under a given condition, and to what degree of dispersion it will occur.

As for how to turn the possibility into reality. And what is the rate of the process, what is the course, thermodynamics cannot give. This is due to the fact that in the classical thermodynamic research method, neither the time factor nor the influence of various factors on the rate of reaction, as well as other details of the reaction proceeding, are taken into account.

In actual production, both thermodynamic and kinetic issues should be considered. If a reaction is thermodynamically judged to be a possible punch judgment, then how to make the possibility a reality and make the reaction possible at a certain rate becomes the main contradiction. If a reaction is thermodynamically impossible, of course there is no need to consider the rate problem.

Many properties and external conditions in a chemical reaction system can affect equilibrium and reaction rate. The balance problem and the velocity problem are interrelated. However, at the current level of understanding, there is no unified quantitative treatment method to link them, and to a large extent, it is necessary to study the equilibrium and chemical reaction rate of chemical reactions separately.

Pressure has a great influence on the volume of gas, and the effect of pressure is considered only when there is a reaction in which gas participates. The volume decreases with increasing pressure, the gas concentration increases, and the reaction accelerates.

There is gas in the forward reaction, there is no gas in the reverse reaction, and when pressurized, the positive reaction accelerates, the reverse reaction remains unchanged, and the equilibrium moves in the positive direction.

There are gases in both the forward and negative reactions, but there are more positive reaction gases, and when pressurized, the positive reaction is accelerated, the reverse reaction is accelerated less, and the equilibrium moves in the positive direction.

When there is the same amount of gas on both sides, the pressure does not move.

Changing the pressure can change the reaction limit, which is for a reaction with gas participation or formation, and the volume change before and after the reaction, that is, the sum of the stoichiometric numbers of the gas in the reaction equation reactant and the product is not equal.

If equal, even changing the pressure will not change the reaction progress.

The forward and reverse reactions are accelerated at the same time, but the different folds of change lead to a shift in equilibrium and a change in the limits of chemical reactions.

Chemical reaction limits and chemical reaction dynamic equilibrium are two different concepts, and the standards for measurement are different, so how can they be confused?