How do you rank Bronsted acids?

Question

Brooklyn Barber · Accepted Answer

Well, not by awarding them gold, silver, or bronze medals. We assess the extent of the following equilibrium:

#HA + H_2O rightleftharpoons H_3O^+ + HO^-# For strong acids, the given equilibrium lies strongly to the right. For #HX (X!=F)#, #H_2SO_4#, #HClO_4#, a given concentration of the acid will be stoichiometric in #H_3O^+# (almost double in the case of sulfuric diacid) as protonolysis proceeds almost quantitatively. For weaker acids, e.g. #H_3C-CO_2H, HF, H_3PO_4#, the protonolysis reaction does not lie completely to the right, and at equilibrium significant concentrations of the free acid are present in solution. Thus, the strength of the acid is determined by the degree of ionization in an aqueous solution.

Isabella Acosta · Answer

undefined Bronsted acids can be ranked based on their ability to donate a proton. This ability is determined by the strength of the acid, which is often measured by its acidity constant (Ka). Generally, a higher Ka value indicates a stronger acid. Additionally, the stability of the conjugate base formed after proton donation also influences the acidity of the Bronsted acid. Therefore, the ranking of Bronsted acids typically follows this order: strong acids have higher Ka values and weaker conjugate bases, while weak acids have lower Ka values and more stable conjugate bases.