Why does chemical equilibrium occur? What is Chemical Equilibrium?

In my opinion, the cause of chemical equilibrium is that neither reactants nor products can unilaterally cause the reaction to proceed in the forward or reverse direction, to use a visual analogy. The reactants and products are like the two sides of a tug-of-war, and neither side has enough strength to win, that is, neither the reactants nor the products can make the reaction forward and reverse thoroughly, so a certain degree of dynamic equilibrium is reached. The positive and negative reaction rates of the chemical reaction are equal, and the concentrations of the components of the reactants and products do not change.

On the other hand, the direction of the chemical reaction is related to the concentration, etc., when the reaction in the positive direction is carried out to a certain extent, the concentration of reactants decreases, and the concentration of products increases, according to the principle of Le Chatlet, the direction of the reaction may be opposite, but eventually equilibrium is reached.

P.S. Compared with the knowledge structure of high school, the explanation in the book is actually very in-depth.

"Deep Cause" means that you are asking for trouble.

The reason for the chemical equilibrium is simple, every change in the world has a process, the difference is only the length of time of this process. Chemical change is actually a process of chemical bond breaking and formation in the reactant molecule and the breaking and formation of the chemical bond of the product, and chemical equilibrium is the equilibrium phenomenon caused by the chemical bond breaking rate in the reactant molecule and the breaking rate of the chemical bond of the product.

Generally speaking, the reaction equilibrium is affected by pressure only when the reactants or gaseous substances are in the product.

In a reversible reaction, which end of the reaction proceeds is affected by the concentration of reactants and products. When there is a gaseous substance in the reactant, the pressure increases, the density of the gaseous substance in the unit volume increases, which is equivalent to an increase in concentration, correspondingly, the chance of this substance coming into contact with another reactant increases, the reaction rate increases, and the reaction equilibrium moves in the positive direction.

Conversely, if there is a gaseous substance in the product, a decrease in the pressure will decrease the density of the gaseous substance per unit volume, which is equivalent to a decrease in concentration, which will also cause the reaction equilibrium to move in a positive direction.

Carbonated beverages such as beer, champagne, and cola should not be shaken vigorously to uncork and produce foam. Formation of tooth decay and protection of teeth. Formation and destruction of stalactites.

Acidosis and alkalosis in the human blood. Electrolyte imbalances in the human body. After CO poisoning, put it in a hyperbaric oxygen chamber or move it to a ventilated place with fresh air (oxygen).

The pressure is not easy to observe, and the reaction can be observed more intuitively by using the concentration representative

Chemical equilibrium refers to the state in which the positive and negative reaction rates of chemical reactions are equal in reversible reactions under certain macroscopic conditions, and the concentrations of reactants and products do not change. It can be judged by δrgm = 0, A is the substance A in the reaction.

Five Balances In high school chemistry textbooks, there is a theoretical system of equilibrium, including dissolution equilibrium, chemical equilibrium, ionization equilibrium, hydrolysis equilibrium, complexation equilibrium, etc.

If you imagine the combustion of acetylene oxygen, if it is natural air combustion, the temperature is very low, but the combustion of acetylene and liquid oxygen (which becomes liquid after compression at high concentrations) is not very different. Combustion is actually a chemical reaction, and combustion with different concentrations is incomplete combustion and complete combustion.

The side quarrel state of chemical equilibrium has to do with many conditions, and whenever the rate of positive and negative reactions is affected and they are no longer equal, the equilibrium is broken by the state of fortune. Common influencing factors are the concentration, temperature, volume, pressure, etc. of reactants or products.

Chemical equilibrium refers to the state in which the positive and negative reaction rates of chemical reactions are equal and the concentrations of reactants and products no longer change in reversible reactions under certain macroscopic conditions.

This is an important theorem in the chemical kinetics of inorganic chemistry - Le Chatelier's principle'keystrokes principle).

This principle can be expressed as follows: "When a factor of the equilibrium state is changed, the equilibrium state will be shifted in a direction that counteracts the effect of the original change of the factor." In other words, if a system in equilibrium is placed in an environment of increased pressure, the system will try to minimize the volume of the body bench and regain equilibrium.

Because of this, the pressure does not increase as much as it should. For example, if the system is placed in an environment where the temperature increases normally, the system will undergo some kind of change and absorb an additional amount of heat.

If you change one of the conditions that affect the equilibrium (e.g., concentration, pressure, temperature, etc.), the equilibrium moves in a direction that can attenuate the change.

1.Concentration: Increasing the concentration of a reactant means that the reaction proceeds in the direction of decreasing the concentration of this reactant, that is, the reaction proceeds in the positive direction.

Decreasing the concentration of a product leads to an increase in the concentration of the product, i.e., the reaction proceeds in a positive direction. Vice versa.

2.Pressure: Increasing the pressure of a gaseous reactant means that the reaction proceeds in the direction of decreasing the pressure of the reactant, that is, the reaction proceeds in the positive direction.

If the pressure of a gaseous product is reduced, the reaction proceeds in the direction of increasing the pressure of the product, and the reaction proceeds in the positive direction. Vice versa.

3.Temperature: If the reaction temperature increases, the reaction proceeds in the direction of reducing heat, that is, the exothermic reaction is carried out in the opposite direction, and the endothermic reaction is carried out in the forward direction; When the temperature is lowered, the reaction proceeds in the direction of heat generation, that is, the exothermic reaction proceeds in the forward direction and the endothermic reaction proceeds in the reverse direction.

4.Catalyst: only changes the speed at which the reaction is carried out, and does not affect the change of equilibrium, that is, the degree of influence on the forward and reverse reactions is the same.

Under certain conditions, when the positive reaction rate of a reversible reaction is equal to the reverse reaction rate of the silver chain, the concentration of the reactants and the concentration of the products no longer change, reaching a state of surface quiescence, i.e"Chemical equilibrium state".Among them, the equality of the positive reaction rate and the reverse reaction rate is the essence of the chemical equilibrium state, and the concentration of reactants and the concentration of the product no longer change is the manifestation of the chemical equilibrium state. The rate of forward reaction and the rate of reverse reaction are for the same reversible reaction, and the positive and negative reactions are only relative and not absolute.

The chemical equilibrium state has six characteristics: inverse, equal, dynamic, fixed, variable and homogeneous. Inverse: The object of Sun Heng's research is reversible reactions.

Equal: At equilibrium, the positive and reverse reaction rates are equal, i.e., v positive = v inverse. Moving:

At equilibrium, the reaction is still ongoing, it is a dynamic equilibrium, and the reaction is carried out to the maximum. Constant: When the equilibrium state is reached, the concentration of each component in the reaction mixture remains unchanged, the reaction rate remains unchanged, the conversion rate of reactants remains unchanged, and the content of each component remains unchanged.

Change: Chemical equilibrium, like all dynamic equilibrium, is conditional, temporary, relative, when the conditions change, the equilibrium state will be destroyed, from equilibrium to disequilibrium, and then establish a new equilibrium under new conditions, that is, the chemical equilibrium has moved. [1] Ibid

The establishment of a state of chemical equilibrium under certain conditions has nothing to do with the pathway of the reaction. That is, whether it starts from the positive and false reactions, or from the reverse reactions, or from any intermediate state, as long as the external conditions are the same, the effect is the same when equilibrium is reached.

The state of chemical equilibrium refers to the state in which the positive reaction rate is equal to the reverse reaction rate in a reversible reaction under certain conditions, and the concentration of each component in the reaction mixture remains unchanged.

Characteristics of chemical equilibrium.

chemical equilibrium is dynamic equilibrium, that is, when in a state of chemical equilibrium, the chemical reaction does not stop, but the forward and reverse reaction rates are equal.

Since the positive and reverse reaction rates are equal when the chemical equilibrium state is reached, the mass fraction of each component in the reaction mixture in this state remains constant and does not change.

The chemical equilibrium is conditional, that is, "fixed" is relative and temporary, while "moving" is absolute. When a condition that affects the chemical equilibrium is changed (e.g., temperature, pressure, concentration), the original chemical equilibrium state is destroyed until a new equilibrium state is established under the new condition.

Theoretically, a reaction involving chemical equilibrium is a reversible reaction, and equilibrium is reached when the speed of the positive reaction is comparable to the rate of the reverse reaction (in other words, the same amount of product is produced per second as it is consumed). The state of chemical equilibrium is related to many conditions, in short, the equilibrium is broken whenever the speed of the positive and negative reactions is affected and they are no longer equal (it is understood that the generation and consumption per second are much different, and naturally the equilibrium is not equal).

Common influencing factors in middle school are the concentration, temperature, volume, pressure, etc. of reactants or products, and how they change needs to be analyzed in detail.

The second question has nothing to do with equilibrium, it is a matter of conservation of materials. Suppose the volume is one liter, then there is H2

This hydrogen must be ** in.

The decomposition of Hi, after decomposition, H2 and I2 are the same, so there is also I2, so there is 1mol of Hi decomposed into H2 and I2. The 1mol decomposed HI plus the remaining 4mol of undecomposed HI must come from the decomposition of NH4i, and NH4I produces as much HI as NH3 when it is decomposed, so NH3 has 1+4=5mol, so the concentration of NH3 is 5mol L.

Chemical equilibrium requires the same concentration of reactants and products to achieve equilibrium?

This is certainly not true.

When the rate of the positive reaction and the rate of the reverse reaction are equal, the chemical equilibrium is reached, and the state of chemical equilibrium is related to the concentration of reactants, products, temperature, pressure, etc., and any of them may break the chemical equilibrium and make the reaction more biased towards the positive reaction or the reverse reaction.

The concentration of reactants and products is not the same, and the key is that the concentration of each component does not change during equilibrium. Or the positive reaction rate and the reverse reaction rate are equal.

There are two reactions in the second question, where the ratio of H2 to Hi in the second is 1:2, so in equilibrium, the Hi concentration is 1mol L, plus 4mol L in the first reaction, and the ratio of NH3 to Hi is 1:1, so.

The NH3 concentration is 5mol l.