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Experiment No. N

Analysis of Aluminum Sulfate (Al³⁺SO₄²⁻)

Aim

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

Preliminary Test

  • Odor: Odorless
  • Texture: Crystalline
  • Color: White
  • Solubility: Soluble in water

Test of Anion

ExperimentObservationInference
Salt + dilute H₂SO₄No reactionDilute H₂SO₄ group is absent
Salt + Conc H₂SO₄No reactionConc H₂SO₄ group is absent
Confirmatory Test
Barium Chloride Test
Salt solution + Dil HCl + BaCl₂ solution		White ppt insoluble in conc. HClPresence of SO₄²⁻ is confirmed

Test of Cation

ExperimentObservationInference
Salt solution + NaOHNo reactionZero group cation is absent
Salt solution + Dil HClNo reactionFirst group cation is absent
Salt solution + Dil HCl + H₂S gas (N₂S chips)No reactionSecond group cation is absent
Salt solution + Dil HCl + NH₄Cl solid + NH₄OH solutionWhite gelatinous pptAl³⁺ may be present
Confirmatory Test
Blue Lake Test
Dissolve the white ppt in HCl + 2-3 drops of blue litmus + 2-3 drops of NH₄OH solution		Blue ppt floating in colorless solutionPresence of Al³⁺ is confirmed

Result

The given salt contains Al³⁺ ions as cation and SO₄²⁻ ions as anion. The salt is Al³⁺SO₄²⁻.

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.