Question

Place the following species in order of increasing Brønsted acidity and briefly explain your reasoning: H₃AsO₃, H₂AsO₂^-, H₃AsO₄, H₂SO₄, H₂SeO₄.

Answer 1

Given acids H₂ AS O₂, H₂ As O2 , H ₂ As Oy , H₂SO4, H₂ Seou are oxy acids. The strength of oxy acids are determine by following factors 1. n-factor :- First write the oxg acid in general formula as. Xon(OH)m I gf whas greater value the acid is stronger acid 2- Effective negative charge (-ves per oratom in the conjugate base. Negative charge - live charge Charge per o-aton Toted no d oratom Smaller the negative charge per oraton stronger the acids. 3- Electronegativity of the central atom. greater the elecponegativity of central atorn Stronger is the acido

Acids HQ ASO3 H₂ ASOł HASO (OH)₂ HASO (OHJ General H₂ AsOy ASOLOH, H₂SO4 Hosen SO2(OH)2 Sed (4) formula Conjugate HASO2 - HASO2 Asoǧ base sou seo -ve charge per o- atom -2% -2/2 -3/4 -2/4 - 2 -0.66 -0.75 -0.5 -0.5 Appling first condition H₂SO44 H₂ Selu wie stronger than rest of acids. Appling Sencond condition Acidic Streagth order H, AsO <H₂ AsOy <H3 ASO, Appling third condition strength order. I elee the negative of s is H₂ Sely <h2sou I greater than sel Thes, finally increasing order of acid shrougth. H₂ AsO <H₃ AsOy LH₂ ASO3 <H₂ Se Ou <H₂ SO4 And