Copper dendrite

Can metal grow like a tree? Let's find out!

Difficulty:
Danger:
Duration:
2 hours

Reagents

Safety

  • Put on protective gloves and eyewear.
  • Conduct the experiment on the safety underlay.
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

Why is the copper dendrite black and not copper-colored?

Why does this copper dendrite look completely different from other copper items, including the rings in the Alchemy experiment from this set?

When exposed to atmospheric oxygen O2, copper Cu is oxidized – it reacts with oxygen to form black copper(II) oxide CuO. As a result, the surface of any copper object is covered with a thin black film that protects it from further oxygen attacks. But why do we only see this film on the dendrite? In fact, the copper rings are also covered with black copper oxide CuO, but this layer is too thin to see with the naked eye. Additionally, the thickness of the copper dendrite is comparable to that of the copper oxide layer covering it, rendering the copper oxide more easily visible.

Can I grow dendrites from other metals?

You can grow other metal trees, too – you just need to choose a suitable pair of metals. One of them has to be eager to transition from an ionic form in a solution to its metallic form, while the other has to be willing to do just the opposite. But how can you determine which metals would want to switch places?

Chemists have a special list called the "metal reactivity series." The farther to the right a metal in this series is, the more it prefers to be in metallic form. Conversely, the farther to the left a metal is, the more it likes to exist in the form of ions. Thus, if you introduce to each other two metals that are both existing in their less-preferred form, they are happy to make a mutually beneficial switch.

Step-by-step instructions

To give your dendrite some support to grow on, place a piece of filter paper in the large part of your Petri dish.

copper-mining_copper-dendrite_en_iks-s-01

CuSO4 solution will serve as a source of copper Cu for the dendrite.

copper-mining_copper-dendrite_en_iks-s-02

To get actual metallic copper Cu out of CuSO4, you can force Zn into the solution in its stead.

copper-mining_copper-dendrite_en_iks-s-03

Slowly but surely, the dendrite grows on the surface of the zinc wire. But why?

copper-mining_copper-dendrite_en_iks-s-04

Disposal

Please refer to local regulations when disposing of chemicals. Dispose of other solid waste with household garbage. Pour leftover solutions down the sink. Wash with an excess of water.

Scientific description

Both zinc Zn and copper Cu are metals. But copper Cu entered the experiment as Cu2+ ions  in the CuSO4 solution, whereas zinc Zn did so as a proper piece of metal . Copper, however, enjoys being in its metallic form far more than zinc does, and zinc doesn't mind venturing into the solution . So when they meet each other, they naturally prefer to switch places. As this happens, the metallic copper  dendrite slowly grows, while the zinc wire gradually dissolves .

That’s interesting!