Kinetic equilibrium of chemical reaction

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SUMMARY

The discussion centers on the kinetic equilibrium of chemical reactions, specifically the dissociation of a compound represented as AB ⇌ A⁺ + B⁻. It is established that the dissociated form is more soluble in a solvent, leading to a faster reaction rate in the forward direction compared to the reverse. The concept of kinetic equilibrium is emphasized, highlighting that the equilibrium does not necessarily indicate the stability of reactants or products. The solubility product (Ksp) is introduced, with examples of weakly soluble salts like PtS and AgI, illustrating the variance in equilibrium constants.

PREREQUISITES
  • Understanding of chemical equilibrium concepts
  • Knowledge of solubility product (Ksp) calculations
  • Familiarity with reaction kinetics and surface area effects
  • Basic principles of solubility and precipitation reactions
NEXT STEPS
  • Research the principles of chemical equilibrium in detail
  • Study the calculation and implications of solubility products (Ksp)
  • Explore reaction kinetics, focusing on surface area effects in solid-state reactions
  • Investigate examples of weakly soluble salts and their equilibrium behaviors
USEFUL FOR

Chemistry students, chemical engineers, and researchers interested in reaction kinetics and solubility dynamics will benefit from this discussion.

sludger13
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I was thinking about this:

Let's consider a dissociation of some chemical that can run in both directions:
AB\rightleftharpoons A^{+}+B^{-}
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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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).
 

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