However, when judging the direction of equilibrium movement, the effect of concentration should stil

In a reversible chemical reaction with the participation of gases, the increase in pressure does represent an increase in concentration, and the root cause of the equilibrium shift due to the change in pressure must also be the change in concentration. Because gas-related problems are very common, widely used, and have great research value, we take them out for separate research. When we study the chemical equilibrium of gases, we do not use concentration, we must use pressure to calculate and explain the problem.

Only in this way can it be adapted to the relevant formula.

Here we would like to emphasize the question "What is the pressure of a gas?" ”

For example, if you give the reaction: 2NO2 = (reversible) = N2O4 We mean the partial pressure of NO2 or N2O4 pressure, not the total pressure of the gas in the container. The partial pressure of NO2 is the pressure contribution of NO2 to the total pressure of all gases in the container, which is equal to the pressure of the same amount of NO2 that exists alone and fills the container.

Therefore, when using Le Chatelier's principle to determine the direction, it is necessary to pay attention to analyzing whether the pressure of each substance has really changed.

In the problem, if NO2 is introduced, the pressure of NO2 increases, and the pressure of N2O4 does not change, so it is easy to understand that the balance is moving in a positive direction. Vice versa.

The question in the link you gave. The answer to the question is wrong. The reaction should move in reverse.

Because the addition of SO3 will only cause a change in SO3 pressure instantly. The answer is even more tricky, and he reverses the equation in the original question to explain a problem that is inherently wrong.

Finally, the H2 question you gave should be relatively simple.

This is Le Chattle's principle, where the reaction proceeds in a direction that reduces the change, and with the addition of NO2 or N2O4, the reaction proceeds in the direction of reducing this change, i.e., reducing NO2 or N2O4.

Constant volume and constant temperature H2+I2=2HI is balanced and then charged with H2, and the reaction naturally moves forward.

First of all, all changes (including pressure) must be translated to concentration before they can be discussed.

First of all, the solids must be excluded! )

2no2==n2o4

At constant volume, both the additive and the reactant are equivalent!

It is all the balance shift to the right, although it is said that if N2O4 is added in the equilibrium, it may be a little bit left shift, but it is an instantaneous change in the reaction rate, and in the end it is still shifted to the right, because when the capacity is constant, the more substances, the reaction moves in the direction of n decrease.

So the other question you asked is the same as the one I asked above. I don't need to explain it.

If the temperature is constant and the volume is constant, H2+I2=2HI is balanced and then charged into H2 and the balance moves to the right.

Because it is filled with a single reactant, it is a little different.

In that question, when SO3 is first added, the reaction does proceed in the direction of the reverse reaction, but the addition of SO3 can be equivalent to adding SO2 and O2 (because the result is the same), and the reaction will move in the direction of the positive reaction after adding SO2 and O2. If H2 is charged after the constant volume and constant temperature H2+I2=2HI are balanced, it cannot be regarded as adding I2 and H2 equally, so the balance will still move.

After the constant temperature H2+I2=2HI is equilibrated, H2 is charged, and the reaction naturally moves forward!!

In middle school, I did not learn the law of partial pressure of gases, so I emphasized "changing the volume of the reactor" for changing the pressure, because changing the volume of the reactor will cause the concentration of each gas component to change to the same extent, (the partial pressure of each gas component changes to the same extent, which is the real sense of changing the pressure.) Therefore, changing the amount of only one gas component, or filling it with inert gas, will not cause the concentration of each gas component to change to the same extent, and it cannot be regarded as "changing pressure", on the contrary, if the amount of each gas component is changed to the same extent, it can be regarded as "changing pressure". Therefore, it is absolutely correct that H2+I2=2HI is balanced and charged into H2 and the balance moves to the right, regardless of constant capacity or constant pressure.

But when solving certain problems, virtual thinking is required, when the direction of movement is not real, but virtual.

If the state of all substances participating in the reaction is gaseous, under the condition of constant temperature and constant capacity, the concentration of reactants is increased, and the equilibrium is moved in the positive direction of the coarse vertical servant.

Your confusion should be in, it's a volume-expanding reaction. If this is a volumetric reaction, or if the volume remains the same before and after the reaction, then you may not hesitate to feel that the equilibrium is moving in a positive direction.

We say that, according to Le Chatre's principle, there is a tendency to move in the direction of the reverse reaction for the expansion of the volume reflection by changing the above conditions, but because the reaction rock noise is very weak, it is not enough to change the overall situation of the positive reaction, and the possible effect is to reduce the speed of the forward reaction, and to reach the equilibrium of the rereaction more slowly.

To give a similar example in life, I don't know if you have ever had the experience of being burned by something hot. The doctor told us that after getting burned by something hot, we should rinse it with cold water to relieve the pain and prevent the injury from spreading. But after treatment, you still find that your hands are blistered, and it still hurts to the touch.

Rinsing with cold water, like Le Chatre's principle, may make the blistering area a little smaller, but it won't change the fact that you're getting burned. Here's an example that I came up with in mind, just for reference.

Hope you have questions.

There are only three factors that affect the equilibrium movement: concentration, pressure and temperature.

1.Effect of concentration on chemical equilibrium.

When other conditions remain unchanged, the concentration of reactants is increased or decreased, and the equilibrium moves to the direction of positive reaction. Decrease the concentration of reactants or increase the concentration of products, and the equilibrium moves in the direction of the reverse reaction.

2.Effect of pressure on chemical equilibrium.

In the reaction with gas participation, gas generation and the number of gas molecules changing before and after the reaction, when other conditions remain unchanged, the pressure is increased (referring to the pressure increased by the volume of compressed gas), and the equilibrium moves in the direction of decreasing the gas volume; Decrease the pressure (i.e., increase the volume of the gas to decrease the pressure), and move the equilibrium in the direction of the increase in the volume of the gas. For example, in the reaction N2O4 (G) - 2 No2 (G), it is assumed that the concentration of N2O4 at the beginning is 1mol L, and the concentration of No2 is 2mol L, K=2 2 1=4; After the volume is halved (the pressure becomes 2 times that of the original), the concentration of N2O4 becomes 2mol L, the concentration of NO2 becomes 4mol L, K becomes 4 2 2 = 8, K increases, so it is necessary to react in the direction of reducing the reaction product (NO2), that is, there are more NO2 reactions to N2O4, reducing the volume of gas, and the pressure is gradually close to the initial state.

Note: When the volume is constant, the increase in pressure caused by the filling of non-reactive gases such as noble gases cannot affect the equilibrium.

3.Effect of temperature on chemical equilibrium.

When other conditions remain constant, the elevated temperature equilibrium shifts to the direction of endothermic reaction.

The combination of the above three factors gives us the principle of Le Chatre, the principle of equilibrium movement

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

Note: The catalyst can only shorten the time required to reach equilibrium, but cannot change the equilibrium state (i.e., percentage composition).

The effect of concentration on chemical equilibrium can be qualitatively illustrated by Le Chatle's principle - increasing the concentration of reactants or decreasing the concentration of products, the equilibrium shifts in the direction of the products, increasing the concentration of products or decreasing the concentration of reactants, and the equilibrium moves in the direction of reactants.

Using the concept of chemical equilibrium, comparing the magnitude of k and j, it is possible to determine whether the reaction mixture in the system is in equilibrium, and in which direction the equilibrium will move. i.e.: j k, the balance shifts to the left; j k, the balance shifts to the right; j = k, equilibrium state is reached.

This relationship is known as the mass criterion of chemical equilibrium and corresponds to the energy criterion above. For memory purposes, it can be abbreviated as: j k

The main factors that affect the movement of chemical equilibrium are concentration. Temperature. pressure, etc.

1) The influence of concentration on the movement of chemical equilibrium When other conditions remain unchanged, increasing the concentration of reactants or decreasing the concentration of products is conducive to the progress of the positive reaction, and the equilibrium shifts to the right; Increasing the concentration of the product or decreasing the concentration of the reactant is conducive to the equilibrium shift of the reverse reaction to the left. A change in the concentration of a single substance simply changes the reaction rate of one of the reactions in the forward or reverse reaction, resulting in an unequal rate of the forward and reverse reactions, resulting in a disruption of the equilibrium.

2) Effect of pressure on chemical equilibrium movement For reversible reactions with unequal molecular numbers of gas reactants and gas products, when other conditions remain unchanged, the total pressure increases, and the equilibrium moves in the direction of decreasing the number of gas molecules, that is, reducing the volume of gas; The total pressure is reduced, and the equilibrium moves in the direction of an increase in the number of gas molecules, i.e., an increase in the volume of the gas. If the total number of molecules (total volume) of the gas does not change before and after the reaction, the change in pressure will not cause the equilibrium to move. For example, if the gas involved in the positive reaction is 3 volumes, and the gas involved in the reverse reaction is 2 volumes, the positive reaction rate increases more when the pressure is increased, so that the positive reaction rate is v positive and v inverse, that is, the equilibrium moves to the direction of the positive reaction; When the pressure is reduced, the positive reaction rate decreases more, and the equilibrium moves in the direction of the reverse reaction.

3) The influence of temperature on the movement of chemical equilibrium When other conditions remain unchanged, increasing the reaction temperature is conducive to endothermic reaction, and the equilibrium moves in the direction of endothermic reaction; Reducing the reaction temperature is conducive to the exothermic reaction, and the equilibrium moves in the direction of the exothermic reaction. Similar to pressure, the change of temperature also changes the rate of forward and reverse reactions at the same time, and the increase in temperature always increases the rate of forward and reverse reactions, and the cooling always decreases the rate of forward and reverse reactions at the same time. For endothermic reactions, the positive reaction rate increases more when the temperature rises, resulting in the result of v positive > v inverse. The rate of reaction in the endothermic direction decreases more when cooling.

Unlike pressure changes, every chemical reaction has a certain thermal effect, so changing the temperature will definitely cause the equilibrium to shift, and there will be no non-movement.

There are three factors that affect the equilibrium movement: concentration, pressure, and temperature.

1.Effect of concentration on chemical equilibrium When other conditions remain unchanged, the concentration of reactants is increased or the concentration of products is decreased, and the equilibrium moves to the direction of positive reaction. Decrease the concentration of reactants or increase the concentration of products, and the equilibrium moves in the direction of the reverse reaction.

2.Effect of pressure on chemical equilibrium In a reaction with gas participation, gas generation and the change of the number of gas molecules before and after the reaction, when other conditions remain unchanged, the pressure is increased (referring to the pressure increased by the volume of compressed gas), and the equilibrium moves in the direction of decreasing the gas volume. Decrease the pressure (i.e., increase the volume of the gas to decrease the pressure), and move the equilibrium in the direction of the increase in the volume of the gas.

3.Effect of Temperature on Chemical Equilibrium When other conditions remain constant, the elevated temperature equilibrium shifts in the direction of endothermic reaction. The temperature equilibrium is lowered and shifted in the direction of exothermy.

The influence of these three factors on the equilibrium shift can be attributed to the magnitude of the q (concentration quotient) and k (equilibrium constant) of the reaction.

q k, the balance is moving in the positive direction.

q=k, the balance does not move.

q k, the balance moves in the opposite direction.

For example, the concentration, the addition of reactants, causes q (the concentration quotient of the product to the concentration quotient of the reactant) to decrease, while k does not change, so q k, the equilibrium moves positively; The effect of pressure can also be attributed to the effect of concentration, while temperature affects the equilibrium constant k itself, unlike the first two.

I hope it helps you, if there is anything you don't understand, you can ask

There are three factors that affect the balance movement.

1.Concentration When other conditions remain unchanged, the concentration of reactants is increased or decreased, and the equilibrium moves to the direction of positive reaction. Decrease the concentration of reactants or increase the concentration of products, and the equilibrium moves in the direction of the reverse reaction.

2.Pressure In a reaction with gas participation, gas generation and the number of gas molecules changing before and after the reaction, when other conditions remain unchanged, the pressure is increased (referring to the pressure increased by the volume of compressed gas), and the equilibrium moves in the direction of decreasing the gas volume; Decrease the pressure (i.e., increase the volume of the gas to decrease the pressure), and move the equilibrium in the direction of the increase in the volume of the gas.

3.Temperature When other conditions remain constant, the elevated temperature equilibrium shifts in the direction of endothermic reaction. The temperature equilibrium is lowered and shifted in the direction of exothermy.

Ion concentration, temperature, acidity.

In a closed container with constant temperature and volume (constant volume), the pressure is changed, and if the amount of gas before and after the reactant is high, it is equivalent equilibrium; If the amount of gas before and after the reaction is not equal, the equilibrium will move in the direction where the pressure can be reduced.

aa(g) +bb(g) -cc(g) +dd(g)

If a+b=c+d: the volume is reduced, the pressure is increased, and the concentration increases, but the equilibrium does not move