Is the reversible reaction equilibrium when the density is fixed 10

Density = mass m volume v

In chemical reactions, the mass is conserved, that is, the mass m does not change during the reaction, so in a container with a constant volume, the density does not change, and the reaction cannot be judged to be in a certain equilibrium; Conversely, in a vessel with variable volume, the density does not change if the volume does not change, and the reaction equilibrium can be judged.

n total = m total m total.

In the process of reaction, the sum of m and m always remain unchanged, so when the number of gases before and after the reaction is unchanged, the amount of matter remains unchanged, and the reaction cannot be judged to be in a certain equilibrium; On the contrary, when the number of gas molecules is variable before and after the reaction, and the amount of matter remains unchanged, the reaction can be judged to have reached equilibrium.

First of all, the density refers to the density of the gas in the equilibrium mixture, that is: m (gas) v (the volume of the gas), and for the case of a certain volume of the container, the volume of the container is the volume of the gas.

1) Before the first reaction reaches chemical equilibrium, the total mass of the gas is always changing (because A is a solid, if the mass of A from the positive reaction to equilibrium is decreasing and converted into gas C and D), the total volume is the volume of the closed container has been unchanged, so before the equilibrium, with the change of the gas mass, M (gas) V (the volume of the gas) has been changing, that is, the density has been changing, and when the density does not change at a certain time, it means that the total mass of the gas has not changed, Then the mass of each component gas is unchanged, that is, the mass of the gas produced by the forward reaction is equal to the amount of gas consumed by the reverse reaction, that is, the positive and reverse reaction rates are equal. Therefore, the density in the first reaction vessel must indicate that the reaction has reached equilibrium.

2) In the second reaction, each substance is a gas, and the reaction is carried out in a closed container, and no one runs out, so no matter whether it is unbalanced, the total mass of the gas remains unchanged, and if it is reacted in a closed container with a certain volume, V (the volume of the gas) is also a fixed value, so no matter when, M (gas) V (the volume of the gas) remains unchanged, that is, the density has always been unchanged, so the second reaction cannot be judged to reach equilibrium by the same density.

And the second question you asked, for a reversible reaction with an unequal number of gas molecules before and after the reaction, the total amount of matter is constant, and the chemical equilibrium state can be determined. Examples are as follows:

N2+3H2=2NH3 (the middle should be a reversible number) (the condition is high temperature and high pressure, catalyst), the sum of the coefficients on the left is 1+3=4, and the right side is 2, such a reaction is a reversible reaction with an unequal number of gas molecules before and after.

I don't know if the current high school chemistry has changed First, the equilibrium can be determined, because a is S (that is, solid), so the mass of the gas on the left and right sides of the reaction formula is unequal, and the volume of the airtight is constant, so the density does not change when the equilibrium. The second is not good, the principle is the same, the reaction formula is equal to the mass of the gas, and the density remains unchanged when the reaction is carried out.

Hey, I haven't done a chemistry example for a year, I can't think of it.

Example: 1: s+no2==no+so

2: 2NH3==N2H4(hydrazine)+H2

The two-style giant pit, reluctant to hand in homework, let's listen to the lecture in class

This question cannot be said in general, but it is necessary to divide the situation:

Assuming that the substances before and after the reaction are gases, and the reaction is carried out in a closed container with a fixed volume, then the density = gas mass and container volume, which is always the same, cannot be used as a basis for judging that the chemical reaction has reached equilibrium.

However, if there are non-gaseous substances before and after the reaction, then the mass of the gas will change when it is not equilibrium, so the density will also change, that is, the density can be used as the basis for judging that the chemical reaction reaches equilibrium.

Of course, if the container body is variable (constant pressure change), and the volume of gas before and after the reaction also changes, then even if it is a reaction in which the gas participates, the degree of the code can be used as the basis for judging the equilibrium of the chemical reaction.

It may be a characteristic of equilibrium when the volume is variable or when there are solids.

When reversible reactions.

When the equilibrium state is reached, the concentration of each substance does not change anymore, and the limit of chemical reaction is reached, so it is not bent;

When the reversible reverse burial should reach the equilibrium state, the forward and reverse reaction rate.

equal, but not zero, so correct;

Chemical equilibrium. For the sake of dynamic equilibrium, because the forward and reverse reaction rates are equal, the concentration of reactants and raw and noisy compounds does not change, so it is wrong;

The chemical equilibrium is a dynamic equilibrium, and when the external conditions change, the equilibrium shifts, so it is wrong;

So choose A

a. The concentration of each component no longer changes, and the reversible reaction reaches equilibrium, so a is correct;

b. The forward and reverse reaction rates are equal, but not 0, which is dynamic equilibrium, so B is wrong;

c. The concentration of reactants is less than the concentration of the products, which is not constant, so C is wrong;

d. It is a dynamic equilibrium, and the forward and reverse rates are greater than 0, so d is wrong; So choose A

1 Equilibrium constant.

k is only affected by temperature, and has nothing to do with the change in the concentration of any reactant or product, nor with the change of pressure and width; Since the catalyst changes the forward and reverse reaction rates to the same extent.

Therefore, the equilibrium constant is not affected by the catalyst.

2 Any reversible reaction, when the temperature remains unchanged and other conditions affecting the chemical equilibrium are changed, even if the equilibrium shifts, the k-value.

No change. 3. When other conditions remain constant, if the forward reaction is an endothermic reaction, K increases (or decreases) due to the equilibrium shifting to the direction of the positive (or reverse) reaction when the temperature is increased (or decreased); If the positive reaction is an exothermic reaction, k decreases (or increases) due to the shift of the deficit equilibrium to the reverse (or positive) reaction direction when the temperature is increased (or decreased); Therefore, the equilibrium constant may increase or decrease as the temperature increases, but it does not change.

Use the product of the ion concentration at any time to eliminate the balance and balance the precipitate dissolution equilibrium constant.

Relative Qing ratio, i.e., solubility product rule: oiksp

Generate precipitate. oi

KSP precipitate dissolves equilibrium. oiksp

The solution dissolves. That is, when the product of the concentration of any ion is less than the equilibrium constant ksp, the solution will dissolve. For example, to determine whether AGCL is soluble, you need to look at the silver ions in the solution.

concentration and chloride ions.

What is the concentration, if any.

c（ag+)*c(cl-)

ksp(agcl)

The precipitate dissolves.

No, because the total mass of the substance before and after the mass conservation reaction does not change, and because it is in the same container, the total volume does not change, and the density is equal to the ratio of the mass to the volume of the substance, so the density is unchanged before and after the reaction.

Sometimes you can, sometimes you can't

The equilibrium state is a state in which the macroscopic rest, and the microscopic forward and reverse reactions continue but at equal rates, so the physical quantities remain unchanged at the time of equilibrium. The way to judge whether equilibrium is reached when the density is certain is: assuming that the equilibrium shifts to the right, if the density changes, then the density must indicate that the equilibrium has been reached; Otherwise, assuming that the equilibrium shifts to the right and the density does not change, the density must not indicate that the equilibrium has been reached.

For the purposes of this question, the density is equal to the mass of the gas divided by the volume of the container, the first reaction, shifted to the right, the mass of the gas increases, and if the volume of the container does not change, the density increases, so the density must indicate that equilibrium is reached. The mass of the second reaction gas is always the same, and the density is always the same, so the density must not indicate that equilibrium is reached.

Whether the amount of total matter must indicate equilibrium is consistent with the above reasoning.

First understand the state of matter in chemical equilibrium. In equilibrium, the two most basic characteristics are: v positive = v inverse; The concentration of the components in the mixture is unchanged.

In other words, to judge whether a reversible reaction has reached an equilibrium state, it is enough to look at these two points. In this question, it is to see if the concentration of each component in the mixture has changed.

Density = total mass of gas Total volume of gas. Since it is in an airtight container, the volume does not change.

In the first reaction, because A is a solid, it is obvious that the total mass of the product gas is greater than the total mass of the reactant gas (if you don't understand it, think of the law of conservation of mass), so once the density does not change when this reaction is carried out to a certain extent, then it means that the degree of "A and B react to form C and D" and the degree of "C and D reaction to form A and B" are equal, that is, the reaction reaches equilibrium.

In the second reaction, because the substances involved in the reaction are all gases, the density does not change in this system. This means that a certain density does not necessarily reach an equilibrium state.

Your teacher may say in the course of the lecture that the special signs of judging balance, such as density and pressure, are actually based on the two most basic characteristics, and there will definitely be applicable conditions.

Therefore, the amount of total matter must be reacted to reach equilibrium, such as this reaction, AA+BB==QC+MD, which is said when A+B≠Q+M.

The equilibrium of a reversible reaction depends only on whether the concentration or partial pressure of the individual reactants and products satisfies the equilibrium constant under the current reaction conditions.

Do you want to ask if a constant gas density in a closed vessel indicates that the reaction has reached equilibrium? If this is the case, the first reaction you listed is in equilibrium when the gas density is constant, while reaction two is not necessarily in equilibrium.

The equilibrium of the reaction is similar to that of the above by the condition that the amount of total matter is certain, and it is only necessary to see whether the amounts of substances on both sides of the reaction equation are equal. If it is not equal, then it can be said that "the reaction reaches equilibrium when the amount of total matter is constant", for example, a + b == c is in line with this.

1 can be judged as balanced, 2 can not be judged. You have to know the formula for calculating density, the density of a gas is equal to the mass of the gas divided by the volume. As far as your question is concerned...

closed containers, so the volume is a constant value; The mass of the gas before and after the reaction in 1 will change, and the equilibrium is that the mass does not change, so the density does not change; 2. The mass of the gas does not change at any time, so its density does not change either. Therefore, it cannot be judged. The way to judge balance is to see that what has changed remains the same, that is, balance.

Why is the chemical reaction not necessarily reached when the gas density in a reversible reaction is constant, for example:

Gas 1 + Gas 2 - Gas 3 + Gas 4, when the reactants and products are gases, the density of the total gas in a container of fixed volume is always constant. There is no direct relationship between density and chemical reactions.