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Experiment No. N

Analysis of Nickel(II) Sulphide (NiS)

Aim

To determine the presence of anion and cation in the given salt

Preliminary Test

  • Odor: Odor of rotten eggs
  • Texture: Crystalline
  • Color: White
  • Solubility: Soluble in water

Test of Anion

ExperimentObservationInference
Warm the salt with dilute H₂SO₄Colourless gas with smell of rotten eggs is evolvedS²⁻ may be present
Confirmatory Tests
Lead Acetate Test
Pass gas through filter paper dipped in lead acetate solution		Paper turns blackS²⁻ is confirmed
Sodium Nitroprusside Test
Make solution alkaline with NH₄OH (or sodium carbonate extract) and add sodium nitroprusside solution		Purple/violet colouration is producedS²⁻ is confirmed

Test of Cation

ExperimentObservationInference
Original solution + H₂S gas in presence of NH₄OHBlack precipitate is formedGroup IV cation may be present
Dissolve black precipitate in aqua regiaNickel chloride solution is obtainedNi²⁺ may be present
Confirmatory Test
Dimethylglyoxime Test
Make the solution alkaline with NH₄OH and add dimethylglyoxime		Brilliant red precipitatePresence of Ni²⁺ is confirmed

Result

The given salt contains Ni²⁺ ions as cation and S²⁻ ions as anion. The salt is NiS.

Precautions

  1. Handle the chemicals with care.
  2. Don't use excess of chemicals.
  3. Keep the mouth of the test tube away from the face.