What is the oxidation state of sulphur in Caro's acid ( H₂SO₅ )?

Step-by-step solution

By a conventional algebraic calculation, the oxidation state of S in H₂SO₅ would appear to be: 2(+1) + x + 5(-2) = 0 x = +8 However, sulphur belongs to Group 16 and has a maximum possible oxidation state of +6. The anomaly arises because the structure of Caro's acid (peroxomonosulfuric acid) contains one peroxide linkage ( -O-O- ). Thus, it has three oxygen atoms with a normal oxidation state of -2, and two oxygen atoms in the peroxide linkage with an oxidation state of -1. The correct calculation is: 2(+1) + x + 3