Question

Which of the following oxoacids of sulphur contains \(S\) in two different oxidation states?

• A. \(H_2S_2O_3\)
• B. \(H_2S_2O_6\)
• C. \(H_2S_2O_7\)
• D. \(H_2S_2O_8\)

Answer 1

The Correct Option is A

 To determine which oxoacid of sulphur contains sulphur (\(S\)) in two different oxidation states, we need to analyze the structures and oxidation states of sulphur in the given compounds:

1. Let's consider the compound \(H_2S_2O_3\) (thiosulfuric acid).
   • The structure of \(H_2S_2O_3\) involves one sulphur atom bonded to three oxygen atoms and another sulphur atom bonded to one sulphur atom.
   • The oxidation states of the sulphur atoms can be calculated as follows:
   • Let the oxidation state of the first sulphur be \(x\) and that of the second sulphur be \(y\).
   • The equation can be set up as: \(2H (+1) + 2S (x, y) + 3O (-2) = 0\), which simplifies to \(2 + 2x + 2y - 6 = 0\), giving us \(2x + 2y = 4\).
   • Additionally, structural analysis gives: for the first sulphur \(x = +2\) (bonded with two oxygen) and for the second sulphur \(y = +6\) (bonded via sulphonate linkage).
   • Thus, the oxidation states are \(+2\) and \(+6\), indicating different oxidation states.
2. For \(H_2S_2O_6\) and \(H_2S_2O_7\) and \(H_2S_2O_8\) compounds:
   • In these compounds, both sulphur atoms have the same oxidation state, typically formed by sulphur being fully oxidized.
   • Example: \(H_2S_2O_7\) (pyrosulfuric acid), both sulphur atoms are in the +6 oxidation state.

Hence, the oxoacid of sulphur which contains sulphur in two different oxidation states is \(H_2S_2O_3\).