Scientific winter decorations

Can drawings also conduct electric current?

Safe­ty pre­cau­tions

Warn­ing: only un­der adult su­per­vi­sion.

Equip­ment

  • cal­ci­um ni­trate;
  • graphite dust;
  • beaker with wa­ter;
  • wood­en stick;
  • paint­brush;
  • LEDs;
  • 9 V bat­tery;
  • croc­o­dile clips.

Step-by-step in­struc­tions

Pre­pare an aque­ous so­lu­tion of cal­ci­um ni­trate in a beaker and add some graphite dust to cre­ate elec­tri­cal­ly con­duc­tive ink. Use this ink to draw a snowflake. Con­nect a 9 V bat­tery to the snowflake with croc­o­dile clips and put LEDs on the graphite lines to cre­ate a com­plete cir­cuit – the LEDs light up!

Process de­scrip­tion

Graphite has a spe­cial struc­ture con­sist­ing of flat lay­ers of car­bon. Elec­tric cur­rent can flow along these lay­ers. Adding an elec­trolyte so­lu­tion to its pow­der makes elec­tri­cal­ly con­duc­tive ink. An elec­trolyte is a sub­stance that dis­so­ci­ates into charged par­ti­cles (ions) in an aque­ous so­lu­tion, and there­fore can also con­duct elec­tric cur­rent. Cal­ci­um ni­trate is a per­fect ex­am­ple. The elec­trolyte so­lu­tion helps elec­trons move from one par­ti­cle of graphite to the next. Thus, a thick mass is ob­tained, which you can use to make real liq­uid "wires" in an elec­tri­cal­ly con­duc­tive pat­tern!

A sim­i­lar ex­per­i­ment is in­clud­ed in the “Zinc-car­bon bat­tery” set from the MEL Chem­istry sub­scrip­tion!