Look for chemists who have questions about the limits of chemical reactions

If all the sulfur trioxide is converted into reactants, then NSO2=

no2 = equivalent equilibrium, you know).

Because the reaction is not complete, it is impossible for NSO2 to be.

The same goes for NSO3.

If NSO2=, and the initial concentration is.

Then SO2 reacts, then SO3 is generated, which does not match the data.

Pick B (Equivalence Balance, you know).

Equivalence balance, you know).

The textbook for the second year of high school will explain it very clearly.

It is by the limit method.

If SO2 and O2 react completely, then the SO3 that will be generated plus the original Mo will have Mo, but this is a reversible reaction and cannot be carried out to the end, so A and C will not work.

The amount fraction of SO2 and SO3 in option D is larger than the original, which is not possible.

So the answer is b

The case where SO3 is completely reacted is chosen, and because it is a reversible reaction, it is impossible to react completely, so A is wrong.

C is the case where SO2 and O2 react completely, and because it is a reversible reaction, it is impossible to react completely, so A is false.

According to the principle of conservation of matter, the total concentration of SO2 and SO3 should be, so D is false.

The limit of a chemical reaction is the study of the maximum degree that a reversible reaction can achieve under certain conditions, that is, the dynamic equilibrium of a chemical reaction.

The limit of the chemical reaction is for the reversible reaction, and when the reversible reaction reaches a certain period of time, the speed of the forward reaction of the chemical reaction is equal to the speed of the reverse reaction, and the reaction appears to "stop", which reaches the limit of the chemical reaction.

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 moves 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.

The change in the concentration of a single substance only changes the reaction rate of one reaction in the forward reaction or the reverse reaction, resulting in the unequal rate of the forward and reverse reactions, resulting in the equilibrium being broken.

When other conditions remain unchanged, the temperature of the reaction is increased, which is conducive to the endothermic reaction, and the equilibrium moves to the direction of the endothermic reaction. Reducing the reaction temperature is conducive to the noisy exothermic reaction, and the equilibrium moves in the direction of the exothermic reaction.

Similar to pressure, the change of temperature also changes the positive and reverse reaction rates at the same time, the heating always increases the positive and reverse reaction rates at the same time, and the cooling always causes the positive and reverse reaction rates to decrease at the same time. 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.

1. Concept: The limit of chemical reaction is the maximum degree that can be achieved by studying reversible reactions.

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

3. Description: (1) Most reactions have a certain 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 forward reaction rate and the reverse reaction rate are equal, the concentration of reactants and products does not change, and the reaction reaches a state of chemical equilibrium.

3) A kind of dynamic equilibrium when chemical 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.

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?

1. It can be used as a sign in any case

1) v positive = v inverse (same substance).

2) The content of each component (percentage content, quantity and mass of substance) does not change with time.

3) The consumption (generation) rate of a reactant: the consumption (generation) rate of a certain product = the ratio of stoichiometric numbers.

2. It can be used as a sign under certain conditions

1) For the reversible reaction system in which the colored substance participates or is generated, the color does not change.

2) For the reversible reaction system with the participation or generation of gaseous substances, if the change in the amount of gas substances before and after the reaction is not 0, the average relative molecular weight m of the mixed gas and the total reaction pressure p remain unchanged (constant temperature and constant volume).

3) For the constant capacitance insulation system, the temperature of the system does not change.

3. It cannot be used as a judgment mark:

1) The ratio of the change in the amount or concentration of the substance or the reaction rate of each substance = the ratio of the stoichiometric number (applicable in any case).

2) For the reaction of the whole gas, if the volume of the gas before and after the reaction does not change, the average relative molecular mass m of the mixed gas and the total reaction pressure p remain unchanged (constant temperature and constant volume).

It is affected by the amount of reaction, the speed of the reaction, etc.

a. Only reversible reactions can establish a state of chemical equilibrium, so a is wrong; b. When the limit of chemical reaction is reached, the concentration of reactants and the concentration of products do not change, and the forward and reverse reaction rates are equal, so B is correct; c. The chemical equilibrium is dynamic equilibrium, in the equilibrium state, the forward and reverse reaction rates are equal, but not 0, and it is not a static state, so c is wrong; d. When the external conditions change, the balance moves, and the limit of the chemical reaction changes, so D is wrong Therefore, B

x, y are reduced, reactants. z is an increase, a product.

The amount of matter varies as follows:

x：y：z：x：y：z=1：3：2

The quantity change of the substance of 2min is.

c=n/v=

v=c/t=

The quantity change of the substance of 5 min is.

c=n/v=

v=c/t=

3.The same, because the amount of the substance does not change after 5 min, and the chemical equilibrium state is reached.

---3h2 (g) +n2(g) = 2nh3(g)

Initial (L); 3 1 0

Balance (l): 3-3x 2 1- x 2 x

v total = 3-3x 2 + 1- x 2 + x = 4- x

1. The volume of NH3 in equilibrium:

x / (4-x) = 12%

x = 2, the conversion rate of n2 at equilibrium:

a, it is obvious that the slope of point a is greater than b, that is, (n-n0) t is greater than b because the volume is a fixed value, so the velocity of this point is greater than b

The amount of each substance changes after point b and c.

After the CD,D point, the equilibrium state has been reached, and the amount of each substance does not change.

Therefore, AD is chosen

Select the ad term a than the slope b point c is just the same amount of the two substances, from the diagram we know that the reaction is still moving, t1 and t2 have reached equilibrium, so n(n2) is unchanged.