Salt Analysis: Ammonium Chloride (NH4Cl)
1. Physical Examination of the Salt
| Experiment | Observation | Inference |
|---|---|---|
| Colour | White | Fe2+, Cu2+, Ni2+, Co2+, Mg2+ are absent |
| Smell | Ammoniacal smell | NH4+ may be present |
| Deliquescence | Does not absorb moisture | Non-deliquescent |
2. Dry Heating Test
| Experiment | Observation | Inference |
|---|---|---|
| A pinch of salt is taken in a dry test tube and heated. | Ammoniacal smell along with white sublimate on the inner wall of the test tube. | NH4Cl may be present |
3. Flame Test
| Experiment | Observation | Inference |
|---|---|---|
| Clean platinum wire dipped in conc. HCl, touched with the given salt, and held at the edge of the oxidizing flame of a Bunsen burner. | No characteristic flame observed | Inconclusive |
4. Reaction with Concentrated H2SO4
| Experiment | Observation | Inference |
|---|---|---|
| A pinch of salt is taken in a dry test tube and heated with 2 drops of conc. H2SO4. | Colourless gas evolves with a pungent, suffocating smell. | Chloride, Sulphate may be present |
5. Wet Test for Acid Radical (Chloride Ion, Cl–)
| Experiment | Observation | Inference |
|---|---|---|
| A small aqueous solution of the salt is taken in a test tube. Drops of HNO3 are added, followed by AgNO3 solution. | A highly curdy white precipitate is observed, which is highly soluble in NH4OH solution. | Presence of Cl– confirmed |
Reactions:
Cl– + AgNO3 → AgCl↓ (Curdy white ppt) + NO3–
AgCl + 2NH4OH → [Ag(NH3)2]Cl (Soluble complex) + 2H2O
Cl– + AgNO3 → AgCl↓ (Curdy white ppt) + NO3–
AgCl + 2NH4OH → [Ag(NH3)2]Cl (Soluble complex) + 2H2O
6. Test for Basic Radical (Ammonium Ion, NH4+)
| Experiment | Observation | Inference |
|---|---|---|
| To an aqueous solution of the salt, dilute NaOH solution is added and warmed. | A pungent smelling, colourless gas evolves which makes brown precipitate with Nessler’s reagent. | Presence of NH3 (and thus NH4+) is confirmed |
Reactions:
NH4Cl + NaOH → NaCl + H2O + NH3↑ (Pungent fumes)
K2[HgI4] + NH3 + NaOH → NH2·HgO·HgI↓ + NaI + H2O
NH4Cl + NaOH → NaCl + H2O + NH3↑ (Pungent fumes)
K2[HgI4] + NH3 + NaOH → NH2·HgO·HgI↓ + NaI + H2O
Conclusion for Zero Group Cation
Since a zero-group cation (NH4+) is predicted in the given salt, no further group analysis is done.
Result for Salt 1 (NH4Cl)
- Basic Radical: NH4+ (Ammonium ion)
- Acid Radical: Cl– (Chloride ion)