9.8 Physical Properties of Benzenediazonium Salts 🔬

  • Benzenediazonium chloride (ArN2+Cl–) is a colourless crystalline solid 💎 :contentReference[oaicite:5]{index=5}
  • It dissolves easily in water 💧 and stays steady when cold ❄️ :contentReference[oaicite:6]{index=6}
  • Warm it up and it reacts with water; in the dry state it breaks down quickly, pushing out \(N_2\) gas 🌬️ :contentReference[oaicite:7]{index=7}
  • Benzenediazonium fluoroborate (ArN2+BF4–) will not dissolve in water 🚫💧 and stays stable at normal room temperature 🌡️ :contentReference[oaicite:8]{index=8}

Why These Facts Matter for NEET 📚

  1. The shiny, colourless crystals of benzenediazonium chloride are an easy lab identifier.
  2. Solubility check: chloride is water-soluble, fluoroborate is water-insoluble — a quick distinction often asked in MCQs.
  3. Remember the temperature trick: keep chloride cold for safety; fluoroborate copes fine at room temp.
  4. Dry diazonium salts release \(N_2\) on decomposition — a favorite question when stability trends pop up.