How to make a battery using lemons and limes
An electric current with a touch of citrus!
Only under adult supervision.
- 4 lemons;
- 2 limes;
- 1 orange;
- magnesium and copper plates;
- crocodile clip wires;
- electronic watch;
- iron wool.
Cut an orange in half and insert a magnesium plate and a copper plate into one half. Use crocodile clip wires to connect the plates – and your battery is ready! You can even use it to successfully power an electronic watch! And what if we increase the number of fruits in the circuit? A multimeter indicates that the voltage in the circuit has increased to 12 V. This voltage is high enough to set iron wool on fire!
This battery’s working principle is based on the difference in the standard electrode potentials between copper and magnesium. Magnesium is quite an active metal; its atoms readily give electrons away from their outer electron shells, turning into magnesium ions
Mg²⁺. Mg⁰ - 2e → Mg²⁺
Due to the lack of electrons, a positive charge arises on the magnesium plate. The magnesium plate dissolves gradually when the battery is active. The battery will work until the magnesium plate dissolves completely.
Copper is less active than magnesium. If these 2 metals are connected in one circuit, electrons will migrate from magnesium to copper. The copper plate thus accumulates a negative charge. Lemon juice contains fruit acids, which tend to dissociate into anions and hydrogen ions Н+ (or protons) in solutions. As it turns out, lemon juice acts as an electrolyte – a solution capable of conducting electric current. These protons accept excess electrons from the copper plate, forming hydrogen, which flies away:
2H⁺ + 2e → H₂↑
As a result of these redox processes, electric current will flow through the system when it is closed. A similar experiment is included in the “Chemistry & electricity” set from the MEL Chemistry subscription!