“Potato clock” experiment

How to make a potato battery for a clock

If you wind up on a desert is­land or in the midst of a nat­u­ral dis­as­ter, know­ing what time it is just might help you keep your bear­ings! Have a look at this cool ex­per­i­ment you can do at home!

Safe­ty pre­cau­tions

Don’t eat any food­stuffs in­volved in the ex­per­i­ment.

Reagents and equip­ment:

  • 2 pota­toes;
  • cop­per wire;
  • zinc wire (you can use a zinc-coat­ed nail);
  • croc­o­dile clip wires;
  • elec­tron­ic clock.

Step-by-step in­struc­tions

In­sert one cop­per and one zinc wire into each pota­to. Use one set of croc­o­dile clip wires to con­nect the zinc wire of one pota­to to the cop­per wire of the oth­er pota­to. Use the re­main­ing croc­o­dile clip wires to con­nect the zinc wire to the “–“ ter­mi­nal and the cop­per wire to the “+” ter­mi­nal. The clock should work!

Pro­cess­es de­scrip­tion

Fruit and veg­eta­bles can fuel not only liv­ing be­ings, but elec­tron­ic de­vices too! To ob­tain elec­tric­i­ty from them, we need a few pieces of cop­per and zinc wire (a zinc-plat­ed nail can sub­sti­tute for the lat­ter). If we place these wires in an elec­trolyt­ic medi­um (a sub­stance that, once dis­solved, can con­duct elec­tric cur­rent), by clos­ing the cir­cuit, such as in a house­hold mul­ti­me­ter, we re­ceive the val­ue of the volt­age of this “bat­tery.”

Be­sides starch, pota­toes con­tain a large amount of var­i­ous sol­u­ble salts and acids, which serve as elec­trolyte. The zinc wire in our “bat­tery” serves as a neg­a­tive elec­trode (an­ode), and the cop­per wire serves as a pos­i­tive elec­trode (cath­ode). In this im­pro­vised bat­tery, an ox­i­da­tion re­ac­tion takes place on the an­ode, and a re­duc­tion re­ac­tion takes place on the cath­ode. And if we close this cir­cuit, an elec­tric cur­rent will pass through it, pow­er­ing the clock!

Zn – 2е⁻ = Zn²⁺

Cu²⁺ + 2е⁻ = Cu

Sum­ma­ry re­ac­tion:

Zn + Cu²⁺ = Zn²⁺ + Cu

You can use ba­nanas, ap­ples, or­anges, lemons and many oth­er kinds of food as the “bat­tery.” Try and ex­per­i­ment – sci­ence is a won­der­ful thing!