COMEDK2022ChemistryRedox Reactions
The colour of CrO ₄²⁻ changes to Cr ₂ O ₇²⁻ is
Options
- Ayellow to orange
- Borange to yellow
- Cyellow to blue
- Dorange to blue
Correct answer
A. yellow to orange
Step-by-step solution
The chromate ion CrO ₄²⁻ is yellow in aqueous solution. In an acidic medium, the chromate ion undergoes dimerization to form the dichromate ion Cr ₂ O ₇²⁻ , which is orange in color. The equilibrium reaction is given by: 2 CrO ₄²⁻ + 2 H ⁺ Cr ₂ O ₇²⁻ + H ₂ O . Thus, the color change observed is from yellow to orange. Answer: yellow to orange