Topic 12: Ionization Equilibrium of Weak Electrolytes 168 Sets of Optimized Recombinant Chemistry 10

I'll talk about this problem, let's take acetic acid as an example.

ch3cooh ch3coo- +h+ we increase the concentration of ch3cooh, according to the principle of equilibrium movement, the equilibrium shifts to the right, which is of course no problem and correct, and we add water to dilute it is also moved to the right, which is also correct, these two seem to be contradictory, but in fact they are not.

Increasing the concentration of the reactants and shifting the equilibrium to the right is understandable, and now it's a matter of adding water.

Adding water seems to be the opposite of the above, the concentration of proacetate decreases, but it should be noted that the concentration of the product also decreases at the same time when adding water, and the multiple of the reduction is that the reactant is the same, and there are two kinds of products at this time, that is to say, the degree of reduction in the concentration of the product should be more powerful, which we can also see from the concentration quotient q. In other words, the decrease in the concentration of the product after adding water is the main factor, so it also shifts to the right (from another point of view, the effect of adding water is the same as the increase in volume in a gas reaction that reduces the pressure and the equilibrium shifts in the direction of increased gas production).

Having said all this, I don't know if I can understand, but I've worked hard.

The equilibrium shifts in a positive direction, but its own conversion rate decreases, i.e., the degree of ionization decreases.

In the ionization process of a weak electrolyte, after the equilibrium has been reached, the weak electrolyte is added, and the equilibrium moves in the direction of ionization. But at this point, the degree of ionization is reduced. When we say that the more diluted the more ionized, the more ionized it is, but in fact, the ions produced after ionization have a reduced chance of colliding with each other, resulting in an increase in the degree of ionization.

The ionization equilibrium of a weak electrolyte belongs to a type of chemical equilibrium and has some of the following characteristics: "Inverse" – The ionization of the weak electrolyte is reversible "Dynamic" – The ionization equilibrium is a dynamic equilibrium "Equal" – v (ionization) = v (molecularization) ≠0 "Fixed" – The concentration of molecules and ions in the solution remains unchanged in the ionization equilibrium state. "Change" - The ionization equilibrium is relative and temporary, and when the external conditions change, the equilibrium will shift.

For the ionization of electrolytes, remember that the thinner the more ionized.

For example: CH3COOH===CH3COO- +H+

Increasing the concentration is to increase the concentration of acetic acid molecules, according to the principle of equilibrium movement, to move in the direction of decreasing its concentration, so it is moving forward;

To reduce the concentration, a solvent is added to the solution, most commonly water, so that the concentration of acetic acid molecules, acetic acid ions, and hydrogen ions are decreasing. However, to the right of the unequal sign is that the concentration of the two ions decreases, so the degree of decrease is greater, relatively speaking, it can be seen that only the ion concentration is decreasing, so the equilibrium is shifting forward.

The degree of ionization is the amount of the substance that has ionized the acetic acid molecule divided by the amount of the total substance of the acetic acid molecule.

Increasing the concentration, although the equilibrium is moving forward, the amount of ionized molecules increases, but the total amount of molecules also increases, and the degree of molecular problems increases more than ionization, so the degree of ionization becomes smaller, remember that the balance shift will only weaken the effect, not change the result. Increasing the concentration of acetic acid molecules already reduces the degree of ionization, and no matter how the equilibrium moves, it only weakens the degree of ionization reduction, but does not change the result of its reduction.

The addition of water to dilute and reduce the concentration does not change the total amount of acetic acid molecules, but the equilibrium is shifted positively, so that the ionized molecules become more, that is, the amount of the ionized acetic acid molecules becomes larger, so the ionization degree increases.

1 Definition of ionization equilibrium: a weak electrolyte in an aqueous solution under certain conditions (temperature, solution, concentration).

, the state at which the rate at which the molecules of the weak electrolyte ionize into ions and the rate at which the ions combine into molecules of the weak electrolyte are equal. 2 Characteristics of ionization equilibrium: Ionization equilibrium is a relative, temporary, conditional dynamic equilibrium.

When the weak electrolyte reaches ionization equilibrium under certain conditions, the rate at which the weak electrolyte molecule is ionized is equal to the rate at which the ions recombine into molecules, and the concentration of various ions and molecules in the solution remains unchanged. When the external conditions change, the ionization equilibrium shifts, and the ionization equilibrium is established under the new conditions.