Oxidation state of 'S' in peroxodisulphuric acid and sodium tetrathionate:

Options

A. `+6, +5, 0`
B. `+6, +6, +6`
C. `+6, +4, +2`
D. `+6, +2, 0`

Answer

To determine the oxidation states of sulfur (S) in peroxodisulfuric acid and sodium tetrathionate, we will analyze the structures of both compounds step by step.

### Step 1: Determine the structure of peroxodisulfuric acid (H2S2O8)

1. **Identify the formula**: Peroxodisulfuric acid has the formula H2S2O8.
2. **Draw the structure**: The structure consists of two sulfur atoms connected by an oxygen atom (peroxide linkage) and each sulfur is bonded to additional oxygen atoms and hydroxyl (OH) groups.
3. **Count the oxidation states**:
- Each oxygen in the peroxide linkage contributes -1 to the oxidation state.
- The remaining oxygen atoms are in the form of -O- and =O (double bond), contributing -2 for each double bond and -1 for each single bond.
- The hydrogen atoms contribute +1 each.

### Step 2: Calculate the oxidation state of sulfur in peroxodisulfuric acid

1. **Assign oxidation states**:
- Let the oxidation state of sulfur be x.
- In H2S2O8, we have:
- 2 H: +2
- 2 S: 2x
- 8 O: -8
- The overall charge of the molecule is neutral (0):
\[ +2 + 2x - 8 = 0 \]
\[ 2x - 6 = 0 \implies 2x = 6 \implies x = +3 \]
- However, considering the structure and the bonds, we find that one sulfur is in a +6 oxidation state and the other in a +5 oxidation state.

### Step 3: Determine the structure of sodium tetrathionate (Na2S4O6)

1. **Identify the formula**: Sodium tetrathionate has the formula Na2S4O6.
2. **Draw the structure**: The structure consists of four sulfur atoms connected in a chain with oxygen atoms.
3. **Count the oxidation states**:
- The sulfur atoms are connected by single bonds, and we need to consider the oxidation states based on their connectivity and the presence of oxygen.

### Step 4: Calculate the oxidation state of sulfur in sodium tetrathionate

1. **Assign oxidation states**:
- Let the oxidation state of sulfur be y.
- In Na2S4O6, we have:
- 2 Na: +2
- 4 S: 4y
- 6 O: -12
- The overall charge of the molecule is neutral (0):
\[ +2 + 4y - 12 = 0 \]
\[ 4y - 10 = 0 \implies 4y = 10 \implies y = +2.5 \]
- However, due to the structure, we find that two sulfur atoms are in a +5 oxidation state and two are in a 0 oxidation state.

### Final Answer

- In peroxodisulfuric acid, the oxidation states of sulfur are +6 and +5.
- In sodium tetrathionate, the oxidation states of sulfur are +5 and 0.