Calculating pH of Polyprotic Acids

[Sujin Lim 1H]

Outline 2: Acids and Bases, and in the textbook section 6E.1 state that if the second Ka value is less that the first Ka value divided by 1000, we can consider only the first deprotonation of the polyprotic acid as significant, and find the pH of the acid using the ICE table. However, in the case that KA2 is NOT less than about KA1/1000, how should we go about finding the pH of the polyprotic acid?

[Alex Yeghikian 1C]

I believe in that case, you would have to do multiple calculations and add the concentrations of H⁺. Using H₂SO₄ as an example, you would find the concentrations of HSO₄^- and H⁺, and then from there find the concentrations of SO₄^2- and H⁺. You would sum up the total H⁺ concentration from both these to calculate pH.

[Alison King 3L]

Adding on, I believe the outline said that only H2SO4 should be treated this way, all other polyprotic acids should just be treated as a weak monoprotic acid since their subsequent dissociations are so weak that they don't contribute to the pH