The acidity of the oxoacids was described in Section 16.9, and a larger number of acids are listed in the table below.
(a) What general trends do you see in these data?
(b) What has a greater effect on acidity, the number of O atoms bonded directly to the central atom E or the number of OH groups?
(c) Look at the acids based on Cl, N, and S. Is there a correlation of acidity with the formal charge on the central atom, E?

(d) The acid H₃PO₃ has a pK_a of 1.8, and this led to some insight into its structure. If the structure of the acid were P(OH)₃, what would be its predicted pK_a value? Given that this is a diprotic acid, which H atoms are lost as H⁺ ions?

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E(OH)m PK₂ EO(OH)m pK EO₂(OH)m PK Very weak Weak Strong CI(OH) 7.5 Br(OH) 8.7 I(OH) 10.6 10(OH) Si(OH)4 9.7 SO(OH)₂ 1.8 SO₂(OH)₂ Sb(OH)3 11.0 SeO(OH)2 2.5 SeO₂(OH)2 As(OH)3 9.2 ASO(OH)3 2.3 CIO(OH) 2 CIO₂(OH) -3 NO(OH) 3.4 NO₂(OH) -1.4 1.6 10₂(OH) 0.8 PO(OH)3 2.1 HPO(OH)2 1.8 H₂PO(OH) 2.0 -3 -3 EO3(OH)m pK, Very strong CIO3(OH) -10