Kinetic equilibrium of chemical reaction

In summary, the conversation discusses the concept of dissociation of a chemical in a solvent and the influence of this process on the reaction equilibrium. The idea is that the dissociated form of the chemical is soluble in the solvent, while the undissociated form precipitates. This leads to the reaction proceeding much faster in the direction of the undissociated form, due to its larger surface area for reactions. However, the equilibrium can also be affected by the difference in reaction conditions on either side. It is also noted that for some weakly soluble salts, the equilibrium may shift to the left, but for highly soluble ones, it may not. The equilibrium for this type of reaction is known as the solubility product, with varying
  • #1
sludger13
83
0
I was thinking about this:

Let's consider a dissociation of some chemical that can run in both directions:
[itex]AB\rightleftharpoons A^{+}+B^{-}[/itex]
Dissociated form is soluble in a solvent and undissociated form is not - it precipitates.
Then the reaction proceeds to the left much faster than to the right, because dissociated form possesses much more reaction "surface" (it is dissolved) than a clot (clot reacts only on its surface).
Also a reaction equilibrium moves almost entirely to the left, because reaction conditions (matter phase) differ from one reaction's side to another. Also the reaction equilibrium does not reflect the stability of reactants resp. products, so it's kinda false (or kinetic) equilibrium.

Is this relevant idea in fact? Can some clot placed inside solvent dissociate but dissociated form does almost not exist in the solvent because of this?
Or is this true - if any chemical cannot be dissolved by a solvent, it can be neither dissociated by a solvent?
 
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  • #2
sludger13 said:
Then the reaction proceeds to the left much faster than to the right, because dissociated form possesses much more reaction "surface" (it is dissolved) than a clot (clot reacts only on its surface).

While you are right that solids react only on the surface, it doesn't follow that the precipitation reaction is much faster.

Also a reaction equilibrium moves almost entirely to the left

For a weakly soluble salts - yes. But of well soluble ones - no.

Equilibrium for such a reaction is called a solubility product. Sometimes it is pretty low (predicted Ksp for PtS is something like 10-76, measured Ksp for AgI is something like 10-18), sometimes it is much, much larger (something like 25 for NH4Cl).
 

FAQ: Kinetic equilibrium of chemical reaction

1. What is kinetic equilibrium of a chemical reaction?

Kinetic equilibrium of a chemical reaction refers to the state in which the rate of the forward reaction is equal to the rate of the reverse reaction. This means that the concentrations of products and reactants remain constant over time, although the reactions are still occurring.

2. How is kinetic equilibrium different from thermodynamic equilibrium?

Kinetic equilibrium is a dynamic state where the rates of the forward and reverse reactions are equal, while thermodynamic equilibrium is a static state where the free energy of the system is at its minimum. In kinetic equilibrium, the concentrations of reactants and products are constant, while in thermodynamic equilibrium, the concentrations can vary as long as the free energy remains at its minimum.

3. How can the equilibrium constant be used to determine the position of equilibrium?

The equilibrium constant, represented as K, is a ratio of the concentrations of products to reactants at equilibrium. The magnitude of K can indicate which direction the equilibrium lies towards - a larger K value means the reaction favors the products, while a smaller K value indicates the reaction favors the reactants. The equilibrium constant can also be used to calculate the concentrations of products and reactants at equilibrium.

4. What factors can affect the equilibrium position of a chemical reaction?

The equilibrium position of a chemical reaction can be affected by changes in temperature, pressure, and the initial concentrations of reactants and products. A change in any of these factors can shift the equilibrium towards the products or reactants, depending on the reaction's enthalpy and entropy.

5. Can the equilibrium position of a chemical reaction be altered?

Yes, the equilibrium position of a chemical reaction can be altered by changing the conditions of the reaction, such as temperature and pressure. A change in concentration can also shift the equilibrium position, but it will eventually readjust to reach a new equilibrium state. Additionally, a catalyst can increase the rate of both the forward and reverse reactions, leading to a new equilibrium position.

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