Notebook Theme

Analysis of Iron(II) Bromide (FeBr₂)

Qualitative analysis

Aim

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

Preliminary Test

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

Test of Anion (Br⁻)

ExperimentObservationInference
Take 0.1 g of salt in a test tube and add conc. H₂SO₄ (or add MnO₂ if needed) and warmReddish brown fumes of bromine are evolvedBr⁻ may be present
Confirmatory Tests
Layer Test
Take 1 mL of neutralized extract, add CCl₄/CHCl₃ (or other suitable organic solvent), then add chlorine water dropwise and shake vigorously
Orange-brown colouration appears in the organic layerBr⁻ is confirmed
Silver Nitrate Test
Acidify sodium carbonate extract with dilute HNO₃ (or use water extract) and add AgNO₃
Pale yellow precipitateBr⁻ is confirmed

Test of Cation (Fe²⁺)

ExperimentObservationInference
Salt solution + NaOH solutionDirty green precipitateFe²⁺ may be present
Confirmatory Test
Potassium Ferricyanide Test
Add potassium ferricyanide solution
Dark blue precipitate (Turnbull's blue)Presence of Fe²⁺ is confirmed

Result

The given salt contains Fe²⁺ as the cation (basic radical) and Br⁻ as the anion (acidic radical). The salt is Iron(II) Bromide (FeBr₂).

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.