Citrus battery

How to make a battery using lemons and limes

An elec­tric cur­rent with a touch of cit­rus!

Safe­ty pre­cau­tions

Only un­der adult su­per­vi­sion.

Equip­ment

  • 4 lemons;
  • 2 limes;
  • 1 or­ange;
  • mag­ne­sium and cop­per plates;
  • croc­o­dile clip wires;
  • elec­tron­ic watch;
  • iron wool.

Step-by-step in­struc­tions

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!

Pro­cess­ de­scrip­tion

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!

Try it