To Prepare Prussian Blue: A Practical | Experimental Step-by-Step Guide

4 Min Read


  1. Conical flask
  2. Test tube
  3. Beaker
  4. Glass rod


  1. Conc. HCL
  2. Ethyl alcohol
  3. Potassium perocyanide.
  4. Conc. H2SO4


 Prussian Blue is a deep blue color that’s made by mixing certain chemicals together. It’s used as a pigment in paints and dyes, and it’s known for its intense blue color. It’s been around for a long time and was one of the first synthetic pigments ever made.

Prussian Blue is historically significant as one of the first synthetic pigments. It was discovered in the early 18th century by the chemist Heinrich Diesbach, and it became widely used in art and industry due to its intense blue color and stability.

Iron filing on heating with dil. H2SO4 in air oxidizes to ferric sulphate Ferric sulphate when mixed with potassium Ferrocyanide gives blue colored Prussian blue complex in presence of H2SO4.

HCl + HNO3 → NACl + 2H2O + 2[Cl]

Fe + 3[Cl] →   FeCL3

4FeCL3 + 3K4 [Fe (CN) 6] →Fe4 [Fe (CN) 6] + 12 NACl

FeSO4 + K4 [Fe (CN) 6] →Fe2 [Fe (CN) 6] + K2SO4

FeSO4 + H2SO4 → FeSO4 + H2

2 Fe (SO4)3 + 3K4 [Fe (CN) 6] →Fe4 [Fe (CN) 6]3 + 6H2SO4 + 2H2O


0.5 gram of iron filing was taken in a beaker. Firstly all the required apparatus were cleaned and 2 drops of HCL and 6 drops of HNO3 was added in a test tube called aqua regia. Then, iron filing was dissolved in aqua regia. The reaction was carried out very slowly and stringed with a glass rod and after complete dissolution of iron filings, the solution was added and the solution was changed into deep blue color. Then ½ test tube of ethyl alcohol was added slowly without disturbing the solution. The solution was left for a day and ppt of Prussian was obtained.


Prussian blue Fe4 [Fe (CN) 6] is prepared in lab by using K4 [Fe (CN) 6] in the solution of iron filing and aqua regia.


Hence, Prussian blue can be prepared in lab by using K4 [Fe (CN) 6]. In summary, by dissolving iron filings in aqua regia and subsequently adding ethyl alcohol, a deep blue precipitate known as Prussian Blue was obtained.


  1. Apparatus should be handled with care.
  2. Apparatus should be cleaned before and after use.
  3. Ethyl alcohol should be added slowly from the wall of conical flask without disturbing the solution.
  4. Ensure proper ventilation when handling chemicals to avoid inhalation of fumes.
  5. Wear appropriate personal protective equipment such as gloves and safety goggles to protect against chemical splashes.
  6. Dispose of waste materials according to proper chemical disposal guidelines to avoid environmental contamination.

This highlights the chemical reaction between iron and the reagents involved, demonstrating the careful manipulation required for its synthesis.

Share This Article
Leave a comment

Leave a Reply

Your email address will not be published. Required fields are marked *