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Experiment No. N

Analysis of Strontium Nitrite (Sr(NO₂)₂)

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
Warm the solid salt with dilute H₂SO₄Brown fumes of NO₂ are evolvedNO₂⁻ may be present
Confirmatory Tests
Potassium Iodide Starch Test
Take evolved gas and add KI + starch solution acidified with acetic acid		Blue colour appearsNO₂⁻ is confirmed
Sulphanilic Acid / 1-Naphthylamine Test
Acidify 1 mL of water extract with acetic acid and add sulphanilic acid solution followed by 1-naphthylamine reagent		Red colour is formedNO₂⁻ is confirmed

Test of Cation

ExperimentObservationInference
Original solution + Dilute HClNo reactionGroup I cation is absent
Original solution + Dilute HCl + H₂S gas (with NH₄Cl)No reactionGroup II cation is absent
Original solution + Dilute HCl + NH₄Cl solid + NH₄OHNo reactionGroup III cation is absent
Original solution + NH₄Cl + NH₄OH + (NH₄)₂CO₃White precipitate is formedGroup V cation may be present
Confirmatory Test
Ammonium Sulphate Test
Dissolve white precipitate in dilute acetic acid and add ammonium sulphate solution		White precipitateSr²⁺ is confirmed

Result

The given salt contains Sr²⁺ ions as cation and NO₂⁻ ions as anion. The salt is Sr(NO₂)₂.

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.