For a solution labeled "0.10 M H₂SO₃(aq)," pK_a1 = 1.81 and pK_a2 = 6.91, which of the following is true? A) [H⁺] = 0.2 M. B) The pH is 1.0. C) The pH ~1.5. D) The pH is 0.70. E) The pH ~ 4.4.

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Quizplus · Accepted Answer

The given solution is a diprotic acid (HSO4-) with two dissociation constants (pKa1 = 1.81 and pKa2 = 6.91). The pH of such a solution is not as straightforward to calculate as for a monoprotic acid, but it can be approximated. Given the pKa values, the pH of the solution will be somewhere between the two pKa values but closer to the first pKa because the concentration is relatively low (0.10 M) and the first dissociation is stronger. The pH of ~1.5 is a reasonable approximation, considering it's closer to the first pKa value but not exactly at it, reflecting partial dissociation of the first hydrogen ion.

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