Ukrainian flag appears from narrow black line

A narrow black line on the filter paper is divided into two broad lines (blue and yellow)

Scientific name: Investigation of ion migration on filter paper


Ions in electric field

by ChemToddler

Experiment 7.2 Investigating the migration of ions

by temp qm

Migration of ions in Copper (II) Chromate (VI) Time Lapse (3.30pm to 10:10 am)

by Ewan Drysdale

Migration of Ions in an Electric FIeld

by Downe House Chem


Wear eye protection goggles.

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

Reaction formula

(Cu(NH3)4)CrO4 → (Cu(NH3)4)(2+) + CrO4(2-)

Step-by-step instruction

  1. There are two approaches for performing this experiment - on a filter paper and in a U-tube. Consider only the option on a paper.
  2. Prepare the solution of [Cu(NH3)4]CrO4. Pour half a spatula of copper sulfate pentahydrate into a test tube. Then, add 2 ml of aqueous ammonia. Stir the mixture to complete dissolution of the copper sulfate. Add about a quarter of a spatula of potassium chromate and stir the resulting mixture.
  3. Carefully apply the resulting solution to form a line across the filter paper.
  4. Dry the filter paper. You can repeat steps 3 and 4 several times, applying the solution to the same line. Thus, the experiment will be more spectacular.
  5. Moisten the filter paper with the solution of sodium sulfate.
  6. Fill two Petri dishes with sodium sulfate and drop the ends of the filter paper into them.
  7. Lower electrodes into the Petri dishes. Pass electricity for at least 15 minutes.
  8. Observe the migration of ions.

Scientific background

This experiment demonstrates the migration of ions in an electric field. Cations of ammine copper which are colored blue, move toward the negatively charged electrode (cathode), and chromate-anions which are colored in yellow, move towards the positively charged electrode (anode).


Published on 30 June 2015

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