Explain this acidic strength order $\ce{H2SO4} > \ce{HCl} > \ce{HNO3}$ in acetic acid.

My Attempt

Stability of conjugate base is proportional to the acidic strength of acids in acetic acid.

  1. $\ce{SO4^2-}$ has two resonance structures.
  2. $\ce{NO3-}$ has three resonance structures.
  3. $\ce{Cl-}$ is stable due to octet formation.

As for electronegativity order, Cl is on par with N (almost equal).

According to stability, $\ce{HNO3}$ must me more acidic than $\ce{HCl}.$ Also, electronegativity of N & Cl is almost the same.

So, according to me, the order must be $\ce{HNO3} > \ce{H2SO4} > \ce{HCl}.$

Where am I wrong? Please explain.

  • 3
    $\begingroup$ The anions are so different that "comparing" them for a trend is meaningless. $\endgroup$ – MaxW Sep 21 '19 at 16:28
  • 1
    $\begingroup$ The strength of the acid is not only dependent on the stability of the conjugate base but also on the proton-accepting ability of the solvent (For protic acids). HCl for example, is a strong acid in water and weak acid in pure acetic acid for this reason. $\endgroup$ – Shoubhik R Maiti Sep 21 '19 at 20:51
  • $\begingroup$ @MaxW but such questions are asked in exams.if there is no way to compare them then how should i approach such question in exams. $\endgroup$ – Math Geek Sep 22 '19 at 7:07
  • $\begingroup$ @ShoubhikRajMaiti i want to know more about "Effects of different solution on acid strength ". Can you please add me in a separate chat so that i can ask little bit more. please. $\endgroup$ – Math Geek Sep 22 '19 at 7:16
  • 2
    $\begingroup$ Note that you should consider rather $\ce{HSO4- } $ instead of $\ce{SO4^2-}$ $\endgroup$ – Poutnik Sep 23 '19 at 4:31

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