sulfuric acid pH

[Elaine Xu 1A]

Why is it that only sulfuric acid does not take the first deprotonation into account when calculating the pH of a polyprotic acid?

[Calvin Chen 1L]

This is because sulfuric acid disassociates as a strong acid in its first deprotonation, and during its second, it acts as a weak acid. You do need to take the first deprotonation into account, however, because the first disassociation contributes H3O+ ions and is relevant to the second calculation.

For example, if in the first deprotonation, the sulfuric acid contributes 0.10 M H3O+ to the solution, the initial concentration of H3O+ during your weak acid calculation would start at 0.10. You also need to add the 0.10 M back to the equilibrium concentration for the final concentration.

[Mark Tadros 3L]

We call this Diprotic, because of the H2 in H2SO4, So it still has an extra H to give off, so you would have to do an ICE chart twice for this because after it gives off one H, it still has another, so it would be HSO4 after the first H is given. So, do another ICE chart solve for it and you will be good.