Question

Which Brønsted-Lowry acid is not considered to be a strong acid in water? Which Brønsted-Lowry acid is not considered to be a strong acid in water? H2SO3 H NO3 HBr HI

Answer 1

A Bronsted-Lowry acid is defined as anything that releases H¹⁺ ions.

According to this, let's see the general equations of all of them in H₂O:

H₂SO₃ + 2H₂O ---------> HSO₃^- + H₃O⁺

HNO₃ + 2H₂O ---------> NO₃^- + H₃O⁺

HBr + 2H₂O ----------> Br^- + H₃O⁺

HI + H₂O -----------> I^- + H₃O⁺

If you see these reactions, all of them can actually release H⁺ (H₃O⁺). However, If you see the H₂SO₃, it's conjugate base, can still be dissociated and release H but it can also can still accepts H. A weak acid is an acid that dissociates incompletely, releasing only some of its hydrogen atoms into the solution. Thus, it is less capable than a strong acid at donating protons. These acids have higher pKa than strong acids, which release all of their hydrogen atoms when dissolved in water.

Therefore, the H₂SO₃ is not a strong base.