Are all strong acids the same strength?

Since the six strong acids dissociate completely into their ions, and the reaction goes to completion, does this mean that acids such as $\ce{HI}$ and $\ce{HCl}$ have the same acidic strength?


I know that 0.10 M $\ce{HI\_{(aq)}}$ and 0.10 M $\ce{HCl\_{(aq)}}$ both contain 0.10 M $\ce{H3O+\_{(aq)}}$, which leads me to believe they are equally strong acids. Is this correct?




There's something called the ["solvent leveling effect"](http://en.wikipedia.org/wiki/Leveling_effect). In short, there's a lowest pKa in a particular solvent, based on the basicity of the conjugate base.


In water, you're limited by $\ce{OH-}$. So given the same concentration of $\ce{HI}$ and $\ce{HCl}$ in water, they will indeed have the same pH.


In other solvents, you may have a difference between acids, depending on the pKa.


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No, not all strong acids are the same strength


There are more than just 6 strong acid. 


The acid dissociation constant ($K\_a$) quantifies the [strength of an acid](http://depts.washington.edu/eooptic/links/acidstrength.html). pK is negative log base 10 of $K\_a$. 


Trifluoromethanesulfonic acid pk <-13


Perchloric acid pK = <-9 


HI pK = -9.3


HBr pK = -9


HCl pK = -6


sulfuric acid pK = -3


chloric acid pK = -1


nitric acid pK = -1


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