Monday, June 8, 2026

Oxidising Action of Potassium Dichromate (K₂Cr₂O₇)

Reaction with Alcohol  

- K₂Cr₂O₇ in acidic solution acts as a strong oxidising agent.  

- When alcohol is added to acidified K₂Cr₂O₇:  

  - The alcohol is oxidised to acetaldehyde.  

  - The dichromate ion is reduced to Cr³⁺.  

- Observation: A distinct colour change occurs from orange‑red to green.  

Reaction with Sulfur Dioxide  

- When sulfur dioxide gas is passed through acidified K₂Cr₂O₇:  

  - Sulfur dioxide acts as a reducing agent.  

  - The dichromate ion is again reduced to Cr³⁺.  

- Observation: The solution changes colour from orange to green.  

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