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How do you find the equilibrium constant of a salt?
3mpathogens:
I have to find the pH of a certain formal concentration of triethylammonium bromide, but the appendix of my book only gives me the pKa and Ka of triethylamine. How do I find pKa for the salt?
Borek:
You do know the Bronsted-Lowry theory of acids and bases?
3mpathogens:
--- Quote from: Borek on August 21, 2021, 06:08:57 PM ---You do know the Bronsted-Lowry theory of acids and bases?
--- End quote ---
Well, at least as far as how it defines acids and bases. Is there something I'm missing?
Borek:
There is no such thing as Ka/pKa of a "salt" that is dissociated in the solution. Ka is a property of a molecule or an ion. What does triethylammonium bromide dissociate into? Is one of the produced ions an acid or a base?
3mpathogens:
--- Quote from: Borek on August 22, 2021, 03:24:17 AM ---There is no such thing as Ka/pKa of a "salt" that is dissociated in the solution. Ka is a property of a molecule or an ion. What does triethylammonium bromide dissociate into? Is one of the produced ions an acid or a base?
--- End quote ---
It would dissociate into a triethylamine cation and chloride anion. So Ka is a property of triethylamine. But wouldn't salts of triethylamine dissociate differently depending on the ion paired with triethylamine? For instance, would I use the same Ka (that of triethylamine) for triethylammonium chloride and triethylammonium bromide? Or would they each have a different associated Ka? (And if so, how do you find that Ka?)
Maybe I don't have a clear understanding of how all of this works in general... what should I review to get a better grasp on this? You mentioned the Bronsted-Lowry theory, but is there anything else that would be helpful?
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