Same chapter3 marksDifficulty: Medium
Describe the brown ring test for a nitrate.
Study of Compounds: Nitric Acid
3 marksDifficulty: Medium
Why does concentrated nitric acid turn yellow on standing, and how can the colour be removed?
Original Khojo Papers practice question — not from a past board paper.
Answer
Concentrated nitric acid decomposes slowly in light to give nitrogen dioxide, which dissolves in the acid and colours it yellow or brown. The colour can be removed by bubbling air or carbon dioxide through the warm acid, which drives the dissolved gas out.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The acid is stored in dark bottles to slow the decomposition.
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