Preliminary and Confirmatory Tests for the Ammonium Radical.
1. Setup Experiment
Select Unknown Salt
0
1
2
2. Observation
Reaction StateClear Aqueous
Status: Standby.
Group 0 is tested first to avoid contamination from NH₄⁺ reagents used in later groups. Step 1 will evolve Ammonia gas if present.
3. Chemical Principles
Step 1 (NaOH Test): Heating with strong base displaces volatile Ammonia (NH₃) gas.
A glass rod dipped in conc. HCl is brought near the mouth. NH₃ reacts with HCl vapors to form dense white fumes of solid NH₄Cl.
NH₃(g) + HCl(g) → NH₄Cl(s) (White Fumes)
Step 2 (Nessler's Test): Nessler's reagent (K₂[HgI₄]) in alkaline medium forms a characteristic brown precipitate (Iodide of Millon's base).
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