Which of the following reagents cannot be used for the preparation of hydrogen peroxide ?

Options

A. Sodium peroxide
B. 2 - Ethylanthraquinol
C. Sodium thiosulphate
D. Barium peroxide

Answer

To determine which reagent cannot be used for the preparation of hydrogen peroxide (H2O2), let's analyze the options one by one:

### Step 1: Analyze Sodium Peroxide
- **Reagent**: Sodium Peroxide (Na2O2)
- **Reaction**: When sodium peroxide reacts with hot water, it produces sodium hydroxide (NaOH) and hydrogen peroxide (H2O2).

\[ \text{Na}_2\text{O}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2\text{O}_2 \]

- **Conclusion**: Sodium peroxide can be used to prepare hydrogen peroxide.

### Step 2: Analyze 2-Ethyl Anthraquinol
- **Reagent**: 2-Ethyl Anthraquinol
- **Reaction**: This compound can be oxidized in the presence of oxygen (O2) and a palladium (Pd) catalyst to produce hydrogen peroxide along with an oxidized product.

\[ \text{C}_{14}\text{H}_{12}\text{O}_2 + \text{O}_2 \xrightarrow{\text{H}_2\text{Pd}} \text{H}_2\text{O}_2 + \text{Oxidized Product} \]

- **Conclusion**: 2-Ethyl anthraquinol can also be used to prepare hydrogen peroxide.

### Step 3: Analyze Sodium Thiosulphate
- **Reagent**: Sodium Thiosulphate (Na2S2O3)
- **Reaction**: Sodium thiosulphate is not typically used for the preparation of hydrogen peroxide. Instead, electrolysis of ammonium hydrogen sulfate can be utilized for this purpose.

- **Conclusion**: Sodium thiosulphate cannot be used to prepare hydrogen peroxide.

### Step 4: Analyze Barium Peroxide
- **Reagent**: Barium Peroxide (BaO2)
- **Reaction**: Barium peroxide can react with sulfuric acid (H2SO4) to produce barium sulfate (BaSO4) and hydrogen peroxide.

\[ \text{BaO}_2 \cdot 8\text{H}_2\text{O} + \text{H}_2\text{SO}_4 \rightarrow \text{BaSO}_4 + \text{H}_2\text{O}_2 + 8\text{H}_2\text{O} \]

- **Conclusion**: Barium peroxide can be used to prepare hydrogen peroxide.

### Final Conclusion
After analyzing all the reagents, we find that the reagent that **cannot** be used for the preparation of hydrogen peroxide is **Sodium Thiosulphate (Option C)**.

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