How to make a chemical current source
How to power Christmas light using chemistry
How can you make a chemical current source? Find out with our experiment.
Warning! Conduct the experiment only under adult supervision.
Reagents and equipment
- copper(II) sulfate solution;
- zinc sulfate solution;
- copper and zinc electrodes;
- crocodile clips;
- plastic vials;
- vial holder;
- Christmas lights;
- rectangular pieces of fabric.
Insert copper and zinc electrodes into plastic vials and arrange them so that the metals alternate. Connect the electrodes with crocodile clips so that the electrodes on either side have a free clip. Connect the vials with copper and zinc electrodes with pieces of fabric. Pour copper(II) sulfate solution into the vials with the copper electrodes, and zinc sulfate solution into the vials with the zinc electrodes. We’ve created two connected Daniell cells. Connect the free ends of the clips to an LED — it glows! If you connect more Daniell cells, you can even power Christmas lights!
The principle behind the Daniell cell is based on the difference between the reactivity of copper and zinc. Its voltage is approximately 1.1 volts. Zinc is a more active metal. And each zinc atom easily gives up two electrons, forming zinc ions Zn²⁺, which are released into the solution:
Zn - 2e → Zn²⁺
These electrons migrate to the copper electrode, which develops a negative charge and begins attracting the positively-charged copper ions Cu²⁺ in the copper(II) sulfate solution. These ions accept the available electrons to form metallic copper, which precipitates on the surface of the copper electrode:
Cu²⁺ + 2e → Cu⁰
As they move through the wires from zinc to copper, the electrons create an electric current, which makes the LED glow.
A similar experiment is included in the “Chemistry & electricity” set from the MEL Chemistry subscription.