Keep the diazonium salt cold
"Keep the diazonium salt cold" is a free, interactive Class 12 Chemistry simulation for NEET and JEE, built on the NCERT section "Diazonium salts: making and handling" in Amines. Benzenediazonium chloride kept in an ice bath: a temperature slider shows it surviving at 273–278 K and hydrolysing to phenol with N₂ above ~283 K; reagent choices replace –N₂⁺ by Cl, Br, CN, I, F, H or NO₂. NEET has asked about this idea 5 times in 10 years of papers. JEE Main asked 57 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Diazonium salts: making and handling in Amines. Change the values and watch what happens.
What it shows
NCERT §9.7–9.9
Benzenediazonium chloride kept in an ice bath: a temperature slider shows it surviving at 273–278 K and hydrolysing to phenol with N₂ above ~283 K; reagent choices replace –N₂⁺ by Cl, Br, CN, I, F, H or NO₂.
Controls
3 to try
- Slidertemperature 268–300 K
- Selectreagent CuCl/HCl, CuBr/HBr, CuCN/KCN, KI, HBF₄ then heat, H₃PO₂, warm water
- Readoutssalt remaining %, N₂ released, product
Try this
Make iodobenzene with the salt still intact, then let the bath warm past 283 K and see phenol form.
Common mistake
Diazonium salts can be stored at room temperature / iodobenzene needs a copper salt.
In NEET
10 years of papers
Asked 5 times in 10 years of NEET.
See the past questions: Amines and Diazonium Salts, Amines (chapter)
In JEE Main
42 shifts analysed
57 questions from Amines across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §9.7–9.8
- Diazonium salts have the formula R–N₂⁺X⁻, where R is an aryl group and X⁻ may be Cl⁻, Br⁻, HSO₄⁻, BF₄⁻ and so on. The –N₂⁺ group is the diazonium group.
- Names add 'diazonium' to the parent hydrocarbon and then name the anion: C₆H₅N₂⁺Cl⁻ is benzenediazonium chloride and C₆H₅N₂⁺HSO₄⁻ is benzenediazonium hydrogensulphate.
- Primary aliphatic amines give very unstable alkyldiazonium salts. Arenediazonium salts last for a short time in cold solution (273–278 K); resonance with the ring explains their extra stability.
- Diazotisation is the conversion of a primary aromatic amine into its diazonium salt. Benzenediazonium chloride is made from aniline and nitrous acid (NaNO₂ + HCl) at 273–278 K: C₆H₅NH₂ + NaNO₂ + 2HCl → C₆H₅N₂⁺Cl⁻ + NaCl + 2H₂O.
- Being unstable, the salt is usually used as soon as it is made rather than stored.
- Benzenediazonium chloride is a colourless crystalline solid, readily soluble in water. It is stable in the cold, reacts with water on warming and decomposes easily when dry. Benzenediazonium fluoroborate is insoluble in water and stable at room temperature.
Questions
5 answers
- What does the "Keep the diazonium salt cold" simulation show?
- Benzenediazonium chloride kept in an ice bath: a temperature slider shows it surviving at 273–278 K and hydrolysing to phenol with N₂ above ~283 K; reagent choices replace –N₂⁺ by Cl, Br, CN, I, F, H or NO₂.
- What mistake does the "Keep the diazonium salt cold" simulation fix?
- A common mistake it clears up: diazonium salts can be stored at room temperature / iodobenzene needs a copper salt.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 5 times in 10 years of papers.
- Does JEE Main ask questions from Amines?
- Yes. JEE Main asked 57 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Diazonium salts: making and handling" in Amines (Class 12 Chemistry).
Embed this simulation
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