Copper clip

Cover an iron clip with a layer of copper!

40 minutes
Experiment's video preview
Chemical formula


  • Put on protective gloves and eyewear.
  • Conduct the experiment on the plastic tray.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

The solution runs off the glass slide. How to fix that?

Perhaps, the elastic bands are positioned too close to each other. Wash and dry the slide thoroughly. Slip the bands back onto the slide. Position the elastic bands as close to the edges of the slide as possible (i.e. further away from each other) — then the “puddle” should easily fit within the “borders” and won’t spill.

I can’t get the camera to focus on the paper clip.

A camera with a macro lens on it would only focus on an object at a close distance. Bring your smartphone as close as possible to the paper clip and try your best not to shake the camera when you shoot.

Step-by-step instructions

Prepare a glass slide on which to conduct and observe the reaction.


Prepare the copper salt solution.


Place an iron clip into the solution. Iron is a more active metal than copper.


As a result of a substitution reaction, the iron clip is covered by copper.


Expected result

In 2-4 hours an odd shape copper crystal that looks like coral will grow on the iron paperclip.


Add absorbent, allow it to soak until all liquid has been absorbed. Dispose of the experiment residues along with regular household trash.

Scientific description

Why is the iron clip covered with copper?

Iron is a more active metal than copper, and when it dissolves, it displaces copper from the solution:

CuSO4 + Fe → FeSO4 + Cu↓

Extruded copper covers the clip with a thin layer.

Learn more

It works like this:

  1. Copper in salt is in the form of an ion (Cu2+) - a copper atom, which has two electrons taken away from it.

  2. Copper gets the missing electrons from iron and settles in the form of a metal.

  3. Electrons can be transmitted not only by direct contact of copper ions with iron but also through the resulting copper because metallic copper is a conductor.

  4. Copper settles because it is a less active metal than iron.

Why should we add sodium hydrogen sulfate to the solution?

In order for a copper crystal to form on iron, it is necessary that iron ions dissolve in water. In real life, iron may be coated with a layer of iron oxide or grease, which interferes with the contact with water. To activate the surface of iron we add sodium hydrogen sulfate solution, which acts as an acid.

Learn more

In a solution, sodium hydrogen sulfate dissociates:

NaHSO4 → Na+ + SO42- + H+

As a result, more protons H+ get into the solution. Protons create the acidic medium of the solution.

Basically, if the surface of the clip is well cleaned, the experiment may be performed without adding acid. Try it.

What else, other than iron, may be used in this experiment?

For the deposition of copper, it is important that the metal used is more active than copper. That means it should be harder to take away an electron from copper than from the metal in use. But if the metal is too active, it will react with water releasing hydrogen.

If we look at the series of activity of the main metals, those metals that are left copper, but right of magnesium will suit us:

  • Beryllium (Be)
  • Aluminum (Al)
  • Titanium (Ti)
  • Manganese (Mn)
  • Zinc (Zn)
  • Chromium (Cr)
  • Iron (Fe)
  • Cadmium (Cd)
  • Cobalt (Co)
  • Nickel (Ni)
  • Tin (Sn)
  • Lead (Pb)
  • Antimony (Sb)
  • Bismuth (Bi)

Follow up

Paper clips made of different materials

Try to carry out the experiment using different paper clips: they may be made of iron or steel, plated with zinc (galvanized) or nickel. Which paper clips demonstrated the best results? Compere them!