Acidified `K_(2)Cr_(2)O_(7)` on reaction with hydrogen peroxide give deep blue solution due to formation of

Options

A. `Cr_(2) (SO_(4))_(3)`
B. `CrO_(5)`
C. `CrO_(4)^(2)`
D. `Cr_(2)O_(3)`

Answer

To solve the question regarding the reaction of acidified potassium dichromate (K₂Cr₂O₇) with hydrogen peroxide (H₂O₂) that results in a deep blue solution, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are acidified potassium dichromate (K₂Cr₂O₇) and hydrogen peroxide (H₂O₂). The potassium dichromate is typically acidified using sulfuric acid (H₂SO₄).

2. **Write the Chemical Reaction**:
- The reaction can be represented as:
\[ K_2Cr_2O_7 + H_2O_2 + H_2SO_4 \rightarrow CrO_5 + K_2SO_4 + H_2O \]
- Here, CrO₅ (chromium pentoxide) is formed, which is responsible for the deep blue color.

3. **Understand the Color Change**:
- Potassium dichromate (K₂Cr₂O₇) is orange in color due to the presence of Cr⁶⁺ ions. Upon reaction with hydrogen peroxide, it gets reduced to Cr⁵⁺ ions in CrO₅, which gives a deep blue color.

4. **Balancing the Reaction**:
- To balance the reaction, we need to ensure that the number of atoms for each element is equal on both sides. The balanced equation is:
\[ K_2Cr_2O_7 + 4 H_2O_2 + 2 H_2SO_4 \rightarrow 2 CrO_5 + K_2SO_4 + 4 H_2O \]
- This shows that 1 mole of potassium dichromate reacts with 4 moles of hydrogen peroxide and 2 moles of sulfuric acid.

5. **Conclusion**:
- The formation of chromium pentoxide (CrO₅) is the reason for the deep blue solution observed after the reaction.

### Final Answer:
The deep blue solution is due to the formation of chromium pentoxide (CrO₅).

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