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Analysis of Iron(II) Hydroxide (Fe(OH)₂)

Qualitative analysis

How to do salt analysis · Viva · Quiz

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: Insoluble in water

Test of Anion (OH⁻)

ExperimentObservationInference
Universal IndicatorSolution turns blue or purpleOH⁻ may be present
Confirmatory Test
Phenolphthalein Test
Add phenolphthalein indicator to salt solution		Solution turns pinkOH⁻ 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 OH⁻ as the anion (acidic radical). The salt is Iron(II) Hydroxide (Fe(OH)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.