Which Is More Acidic: H₂SO₄ or H₂SeO₄?

[Bipolarity]

Homework Statement

Which is more acidic, and why?
$$H_{2}SO_{4}$$
$$H_{2}SeO_{4}$$

Homework Equations

The Attempt at a Solution

Because Se is larger, it has a weaker Coulomb force with the H atoms. So it will more readily give up the protons of the H atoms. Hence it should be more acidic, but turns out sulphuric acid is more acidic?

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BiP

 

[chiddler]

The general trend for oxyacids is as follows:

1. The more oxygen that is present, the more acidic the compound is. This is because more oxygens allow more resonance stability.

2. The more electronegative the central atom is, the more acidic it is. This is due to inductive effect where the oxygens that donate a proton are stablized by the central atom that can absorb some of the electron density and stabilize the conjugate base.