Home science: soda battery

Safe­ty pre­cau­tions

Warn­ing: only un­der adult su­per­vi­sion.

Equip­ment

• two small glass­es;
• soda;
• two gal­va­nized screws;
• two cop­per coins;
• croc­o­dile clips;
• dig­i­tal alarm clock.

Step-by-step in­struc­tions

Con­nect a cop­per coin to a gal­va­nized screw us­ing a croc­o­dile clip. Put the coin in one glass, and fix the screw to the wall of a sec­ond glass. Us­ing croc­o­dile clips, con­nect an­oth­er screw to the “–” ter­mi­nal of a dig­i­tal clock, and an­oth­er coin to the “+” ter­mi­nal. Put the sec­ond coin in the glass with the first screw, and fix the sec­ond screw on the wall of the glass with the first coin. When the glass­es are filled with soda, the clock starts work­ing!

Process de­scrip­tion

Met­al screws are of­ten coat­ed with zinc to pre­vent them from re­act­ing with sub­stances from their en­vi­ron­ment (for ex­am­ple, oxy­gen and wa­ter) via a phe­nom­e­non known as cor­ro­sion. Such screws are said to be “gal­va­nized.” Mean­while, soda con­tains what is known as acid­i­ty reg­u­la­tors, of­ten ei­ther cit­ric or phos­phor­ic acid. These sub­stances make the acid­i­ty of the drink suit­able for our bod­ies. When the cir­cuit is closed, these acid­i­ty reg­u­la­tors re­act with zinc and cop­per, elec­tric cur­rent be­gins to flow through the cir­cuit, and the clock starts work­ing! The gal­va­nized screws can be re­placed with an­oth­er met­al, such as iron, but this will di­min­ish the volt­age of the “bat­tery” as iron is less chem­i­cal­ly ac­tive than zinc. You can con­firm this by com­par­ing the po­si­tions of zinc and iron in the elec­tro­chem­i­cal se­ries.

You can choose won­der­ful chem­i­cal project kits and get them on a month­ly ba­sis for your kids.