Notebook Theme

Analysis of Manganese(II) Nitrate (Mn(NO₃)₂)

Qualitative analysis

Aim

To analyse the given inorganic salt for one acidic and one basic radical.

Preliminary Test

  • Colour: Pale pink
  • Odour: Odourless
  • State: Crystalline solid
  • Solubility: Soluble in water

Test of Anion (NO₃⁻)

ExperimentObservationInference
Add conc. H₂SO₄ to the solution and boil with a few copper turnings/chipsOn heating, brown fumes (NO₂) are evolved in excess and the solution becomes blueNO₃⁻ may be present
Confirmatory Test
Brown Ring Test
Take 1 mL of salt solution, add 2 mL conc. H₂SO₄, cool, then add freshly prepared ferrous sulphate solution along the sides
Brown ring is formed at the junction of the two solutionsNO₃⁻ is confirmed

Test of Cation (Mn²⁺)

ExperimentObservationInference
Original solution + H₂S gas in presence of NH₄OHBlack or flesh-coloured precipitate is formedGroup IV cation may be present
Confirmatory Test
Sodium Hydroxide Test
Dissolve the precipitate in dilute HCl by boiling and add NaOH in excess
White precipitate forms first, then turns brown on standingPresence of Mn²⁺ is confirmed

Result

The given salt contains Mn²⁺ as the cation (basic radical) and NO₃⁻ as the anion (acidic radical). The salt is Manganese(II) Nitrate (Mn(NO₃)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.