Why is water included in the acid dissociation equation if its a pure liquid? I thought pure liquids and solids were excluded from k equilibrium equations, Ka is the same as Keq right? Except Ka applies specifically to acids? Please help!
Acid dissociation constant
- Thread starter Regina90
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water isn't included. What is included is H3O+ which is different from H2O. Protons (H+) hardly ever exist in solution isolated, instead they typically get abstracted by any basic compound near them. Typically this is water because we use it as a solvent frequently and therefore it's in large supply.
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At any given time in water you have an equilibrium of H2O and H3O+ and by definition H3O+ is acidic. This is why.
The following is the reaction that takes place.
H2O + H2O --> H3O+ + OH-
pKa = -log(Ka)
Ka = ([H+][A-]) / [HA]
