How to make Ferrofluid

Liquid becomes the shape of a hedgehog when a magnet is held up to it.

Scientific name: Suspension of magnetite particles responds to applied magnetic field.


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Wear eye protection goggles and gloves. From step 3 to step 10 work outdoors or in fume hood.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

2FeCl3 + FeCl2 + 8NH3 + 4H2O → Fe3O4 + 8NH4Cl

Step-by-step instruction

  1. Prepare iron (II) chloride and iron (III) chloride solutions, ammonia solution, oleic acid and kerosene.
  2. Mix iron (II) chloride and iron (III) chloride solutions in 1:2 ratio.
  3. Pour the mixture in ammonia solution.
  4. The second step should be performed outside or in a fume hood.
  5. Heat the solution near boiling.
  6. Add some oleic acid to the solution.
  7. Stir the solution thoroughly.
  8. Continue heating until there will be no smell of ammonia.
  9. To avoid coagulation swirl the flask during heating.
  10. Leave the solution to cool down.
  11. Add kerosene and stir it carefully with a spatula.
  12. Coated particles will migrate into the organic phase.
  13. Stop stirring and let the mixture separate into two layers.
  14. The first top layer is a black suspension of magnetite particles and the second bottom layer is water. Divide the kerosene layer from the mixture. Pour out the water.
  15. The obtained black suspension is ferrofluide. Bring the magnet near it and observe what happens.

Scientific background

Ferrofluides combine properties of liquid and solid and are also magnetic. They could take different shape depending on the applied magnetic field. Ferrofluide represents a colloid suspension of solid magnetic particles of nm size in a liquid carrier. The surfactant is added in order to avoid clamping of particles together and to make the suspension stable. The simplest in preparation ferrofluid consists of magnetite Fe3O4 as a disperse phase and kerosene as a dispersion medium. Oleic acid is used as a surfactant. In order to obtain magnetic particles of required size two iron chlorides are mixed together with ammonia solution. Components react as follows:

2FeCl3 + FeCl2 +8NH3 + 4H2O → Fe3O4 + 8NH4Cl


Published on 15 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst