If the pressure of the reaction system increases, does the reaction rate necessarily increase?

Answer: Obviously this is wrong.

For example, in the case of constant volume, a gas that does not participate in the reaction is added to the chemical reaction, and the pressure increases, and the chemical reaction rate.

No change. Here's why: The rate of a chemical reaction is defined as the change in the concentration of reactants (or products) per unit of time. The amount of the individual reactants and the amount of the product under the above conditions.

There is no change, and the constant volume is constant, so their concentration does not change, so the rate of chemical reaction does not change.

PS: To consider the change in the rate of chemical reaction, we should start from its definition, and analyze the change in concentration per unit time, and then we can understand the change in the reaction rate.

As the pressure inside the container increases, there are two things to do: reduce the volume of the container, or fill it with gas.

Obviously, the former can increase the reaction rate.

However, the latter, if the filled gas does not participate in the reaction.

For example: n2+3h2=nh3

In this reaction system, helium is added and the rate of reaction is constant.

Speeding up the reaction rate is essentially increasing the probability of effective collision of particles.

When substances that do not participate in the reaction are added, the total number of particles increases, so the reaction rate is not affected even if the pressure increases.

The essence of increasing pressure is to increase the concentration of reactants, increase the number of activated molecules per unit volume, and increase the number of effective collisions to increase the reaction rate.

If it is a reaction between a solid and a liquid, the change in volume by increasing the pressure is negligible, so the concentration of the reactants remains unchanged and the reaction rate does not accelerate.

AgNO3+HCl=AGCL+HNO3, the pressure is increased in the solution, and the reaction rate is not accelerated.

Not necessarily, because the pressure only acts on the reaction of the gas. If there is no gas, the pressure will increase, and the reaction rate will not increase.

In the constant capacity container, adding non-reactive gas can also increase the pressure of the reaction system, and the reaction rate remains unchanged.

Other conditions remain the same, the pressure of the reaction with the participation of gas increases, and the reaction rate increases. In fact, what directly affects the reaction rate is the concentration of reactants, and when the pressure increases, the concentration of reactants increases, and the reaction rate can naturally increase. As for the principle, we can take a look at the theory of effective collisions, which mainly means that the reaction is an effective collision between molecules, and increasing the concentration (pressure) can increase the number of effective collisions per unit time, and therefore increase the reaction rate.

The factors that affect the rate of chemical reactions are divided into internal and external factors:

1. Internal causes: the properties of the reactants themselves.

2. External factors: temperature, concentration, pressure, catalyst, light, laser, reactant particle size, contact area between reactants and reactant state. In addition, X-rays, radiation, the contact area of the surface area of the solid substance with the reactants, and the concentration of the reactants also affect the chemical reaction rate.

1. Internal factors. The relationship between the strength of a chemical bond and the rate of chemical reaction. For example:

Under the same conditions, fluorine and hydrogen can occur in the dark** (the reaction rate is very large); Chlorine and hydrogen will occur under light conditions** (large reaction rate); Bromine and hydrogen can only react under heating conditions (the reaction rate is larger); Iodine vapor reacts with hydrogen at higher temperatures, and the resulting hydrogen iodide decomposes (with a smaller reaction rate). This is closely related to the relative strength of the reactant x—x bond and the product h—x bond.

2. External factors. 1.Pressure conditions.

2.Temperature conditions.

3.Catalyst.

5.Other factors.

The effect of pressure on the reaction rate can be explained relatively simply by molecular collision theory, at low pressure, assuming that there are only two molecules in a space of 1 cubic meter, so that it takes a long way for two molecules to collide, so that the probability of collision is very low. At high pressure, assuming that there are 1 mol molecules in a space of 1 cubic meter, this situation is like crowding people compared to the previous low pressure, so that collisions occur almost all the time. The reaction needs to be effectively collided, because the more collisions, the greater the probability of effective collision, so the reaction rate is increased.

Molecular collision model.

For gases, if other conditions remain constant, increasing the pressure is to increase the amount of reactants per unit volume, that is, to increase the concentration of reactants, so that the rate of chemical reactions can be increased. The pressure is reduced and the reaction rate is slowed down.

For chemical reactions with gas participation, when other conditions remain unchanged (except volume), the pressure is increased, that is, the volume decreases, the concentration of reactants increases, the number of activated molecules per unit volume increases, the number of effective collisions per unit time increases, and the reaction rate accelerates. Otherwise, it decreases.

If the volume is constant, the rate of the pressurized reaction (adding gases that do not participate in this chemical reaction) will not change. Because the concentration does not change, the number of activated molecules per unit volume does not change. However, when the volume remains the same, the reactants are added, which is also pressurized, and the concentration of reactants is increased, and the rate will also increase.

If the volume is variable, the constant pressure (adding gases that do not participate in this chemical reaction) reduces the reaction rate. Because the volume increases, the amount of reactant substances does not change, the concentration of reactants decreases, and the number of activated molecules per unit volume decreases.

The rate of a chemical reaction is an indication of how fast a chemical reaction proceeds. It is usually expressed as the change value (reduction value or added value) of the concentration of reactants or products per unit time, and the reaction speed is related to the nature and concentration of the reactants, temperature, pressure, catalyst, etc., and if the reaction is carried out in solution, it is also related to the properties and amount of solvents.

Increase the pressure of the reaction system, and the reaction rate is high.

Not necessarily enlarged.

There are three ways to increase the pressure of the reaction system:

The volume is compressed and the reactants are filled (the volume is constant).

Charge with non-reactive gases such as noble gases.

volume is certain).

The first two methods can increase the reaction rate, and the third method has no effect on the reaction rate.

Therefore, when the pressure of the reaction system increases, the reaction rate will increase if the reaction rate is different.

The essence of increasing the pressure is to increase the concentration of reactants, increase the number of activated molecules per unit volume, and increase the number of effective collisions to increase the reaction bending rate.

If it is a reaction between a solid and a liquid, the change in volume by increasing the pressure is negligible, so the concentration of the reactants does not change in stages, and the reaction rate does not accelerate.

AgNO3+HCl=AGCL+HNO3, the pressure is increased in solution, and the reaction rate is not accelerated.