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 state of sulfur (S) in peroxodisulfuric acid (H2S2O8) and sodium tetrathionate (Na2S4O6), we will follow these steps:

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

1. **Identify the components**: The formula H2S2O8 indicates that there are 2 sulfur (S) atoms and 8 oxygen (O) atoms.
2. **Understand the peroxo linkage**: In peroxodisulfuric acid, there are two -O-O- (peroxo) linkages between the sulfur atoms.

### Step 2: Assign oxidation states in peroxodisulfuric acid

1. **Assign oxidation states for oxygen**: Oxygen typically has an oxidation state of -2. However, in the peroxo linkage (-O-O-), each oxygen has an oxidation state of -1.
2. **Calculate total oxidation state for oxygen**:
- For the 6 oxygen atoms (4 in -O- and 2 in -O-O-):
- 4 O at -2 = 4 * (-2) = -8
- 2 O at -1 = 2 * (-1) = -2
- Total = -8 - 2 = -10
3. **Set up the equation**:
\[ 2(H) + 2(S) + (-10) = 0 \]
\[ 2 + 2S - 10 = 0 \implies 2S = 8 \implies S = +4 \]
Each sulfur atom in peroxodisulfuric acid has an oxidation state of +6.

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

1. **Identify the components**: The formula Na2S4O6 indicates that there are 4 sulfur (S) atoms and 6 oxygen (O) atoms.
2. **Assign oxidation states for sodium**: Sodium (Na) has an oxidation state of +1.

### Step 4: Assign oxidation states in sodium tetrathionate

1. **Assign oxidation states for oxygen**: Oxygen typically has an oxidation state of -2.
2. **Calculate total oxidation state for oxygen**:
- For 6 oxygen atoms:
\[ 6 \times (-2) = -12 \]
3. **Set up the equation**:
\[ 2(Na) + 4(S) + (-12) = 0 \]
\[ 2(1) + 4S - 12 = 0 \implies 2 + 4S - 12 = 0 \implies 4S = 10 \implies S = +2.5 \]
However, since sulfur can have whole number oxidation states, we can analyze the individual sulfur atoms:
- The oxidation states of the sulfur atoms can vary, but typically in tetrathionate, they are +2, +2, +5, and +5.

### Final Answer:
- The oxidation state of sulfur in peroxodisulfuric acid (H2S2O8) is +6.
- The oxidation states of sulfur in sodium tetrathionate (Na2S4O6) are +2, +2, +5, and +5.