My professor is really general... In one of her questions she wants us to look at the equilibrium equation for the dissociation of aicd HCl into ions.
Eq=[H][Cl]
& wants to know what an "appopriate value for Ka would be"...
She didn't give us any numbers so I know she is looking for an answer like negative, or really small, or positive & wants us to justify it. But I missed yesterday's lecture & don't understad... Help!!!
2007-09-20 06:36:14 · 3 answers · asked by Anna 4 in Science & Mathematics ➔ Chemistry
ADDED QUESTION:
Why is the value negative?
2007-09-20 06:46:57 · update #1
It is a really big number. In reality it does not matter in aqueous solution, since everything will be converted into hydronium and chloride ion-, that is why we write the reaction in one direction only.
HCl (aq) ==> H+ + Cl-
The acid is 100% dissociated, so every single last molecule of HCl will be converted into H+ and Cl-. For strong acids in the gas phase it does make a difference, but if you are dealing with aqueous solutions, talking about Ka values for strong acids is irrelevant.
That is why for any strong acid, the pH of the solution is -log([strong acid]), so solutions of 0.1 M HCl, HBr, HI, HNO3 and HClO4, all will give you the same pH, 1.0.
Any strong acid when dissolved in water is converted into H+, since H+ is the strongest acid that can exist in water. That is called the leveling effect.
In essence, using this approach, you can say that the Ka of any strong acid approaches infinity, any number divided by zero is in essence infinity.
Still, I do not see any pedagogical value in this type of question. The Ka of any strong acid is irrelevant in the calculations that you have to perform using that strong acid.
2007-09-20 06:50:25 · answer #1 · answered by William Q 5 · 19⤊ 0⤋
Ka Of Hcl
2016-10-06 12:52:09 · answer #2 · answered by ? 4 · 0⤊ 2⤋
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HCl is a "strong" acid, meaning it dissociates completely in water. As opposed to a "weak" acid, like acetic acid. That is true regardless of how concentrated or dilute it is, which is a different matter. "Strong" does NOT mean concentrated in chemistry.
2016-03-27 02:10:30 · answer #3 · answered by Anonymous · 0⤊ 0⤋
A strong acid is completely dissociated so there is no Ka since Ka is only used with weak electrolytes partially dissociated
2007-09-20 07:21:27 · answer #4 · answered by maussy 7 · 3⤊ 0⤋
Probably, but I am not convinced
2016-09-20 12:58:27 · answer #5 · answered by ? 4 · 0⤊ 0⤋
Finally, that's what I was exploring for! Thanks op of this question.
2016-08-24 16:46:12 · answer #6 · answered by Anonymous · 0⤊ 0⤋
pKa = -7, that is, the acid completely dissociates into ions; H+ and Cl-
2007-09-20 06:44:03 · answer #7 · answered by Peter B 3 · 1⤊ 20⤋