This document provides a procedure for preparing Prussian Blue (Fe4[Fe(CN)6]3) in 3 steps: 1) Iron filings are oxidized with sulfuric acid to form ferrous sulfate. 2) Ferrous sulfate is further oxidized with nitric acid to form ferric sulfate. 3) Ferric sulfate is reacted with potassium ferrocyanide to form Prussian Blue precipitate. The yield of Prussian Blue obtained following this procedure was 5.05 g.

1. Preparation of Prussian Blue,
Fe4[Fe(CN)6]3
By
Dr Bhavana P Khobragade
RDIK and NKD College Badnera

2. Prussian Blue

3. Theory
The complex iron hexacyano ferrate is known as
prussian blue
It is obtained by oxidation of iron, Fe to Fe3+, followed
by reaction with potassium ferrocyanide.
Fe + H2SO4 → FeSO4 + H2
2FeSO4 + H2SO4 +[0]→ Fe2 (SO4)3 +H20
Fe2 (SO4)3 + 2K2[Fe(CN)6]3 → Fe4[Fe(CN)6]3 + 5K2SO4
Fe → Fe4[Fe(CN)6)3
MW = 55.85 g MW = 859.25 g

4. Apparatus : 100 ml beaker, measuring
cylinders, etc.

5. Chemicals
Iron filings, potassium ferrocyanide, dil.Sulfuric Acid,
Conc. HNO3, ethanol, etc.

6. Procedure
 Take 0.5 g of iron filings in a beaker.
 Add 10 ml of dil. sulfuric acid.
 Heat it on a wire guaze.
 The reaction becomes vigorous
 Remove the burner and cool the solution.
 When the reaction subsides, decant the supernatant liquid in
another beaker.
 Add 10 ml of dil. sulfuric acid
 Repeat the procedure till whole iron filings are dissolved.
 Combine the solution of ferrous sulfate and heat it.
 Add 0.5 ml conc. HNO3 and boil to oxidize iron to ferric state.
 The solution becomes yellow. Continue boiling for 5 minutes to
expel fumes of NO2 gas and nitric acid.
 Add the saturated solution of 4.5 g of potassium ferrocyanide.
 Heat the solution until it acquires green color.
 Keep the green colored product in air for 2 hours
 It changes to blue.
 Filter the product, wash with a little alcohol, dry and weigh it.

7. Result : Yield of of Prussian Blue is 5.05 g.

8. Note
• Addition of 1-2 ml of K2Cr203 will increase the
oxidation öf green product.
• Prussian blue may also be obtained by the
reaction of potassium ferrocyanide with ferric
chloride.
• Prussian blue may be manufactured by
roasting mixture of iron filings, potassium
carbonate and organic proteinous matter. But
no satisfactory yields

9. Thanks