How to make an alloy that resembles mercury

Experiments with an alloy made from indium and gallium

Safe­ty pre­cau­tions

Wear pro­tec­tive gloves.

Reagents and equip­ment

  • gal­li­um;
  • in­di­um;
  • a Petri dish;
  • a plas­tic vial with a cap;
  • an LED and pow­er source;
  • a cot­ton swab;
  • a sy­ringe.

Step-by-step in­struc­tions

Rub the gal­li­um and in­di­um against each oth­er over the Petri dish. No­tice that the met­als dis­solve in one an­oth­er. Trans­fer a few drops of the re­sult­ing al­loy into the plas­tic vial, cap it, and shake. Ob­serve the for­ma­tion of a metal­lic “mir­ror.” Use the cot­ton swab to draw an un­bro­ken line through the Petri dish. Use this line to close an elec­tri­cal cir­cuit with an LED diode – the diode should light up.

Process de­scrip­tion

In­di­um and gal­li­um form an al­loy con­sist­ing of 75.5% gal­li­um and 24.5% in­di­um, of­ten called a gal­li­um in­di­um eu­tec­tic al­loy. Its main ad­van­tage lies in its melt­ing point, 16 °С (61 °F), which makes it a prospec­tive re­place­ment for the dan­ger­ous mer­cury in de­vices such as ther­mome­ters. It also coats sur­faces well, in­clud­ing plas­tic sur­faces, form­ing a “metal­lic mir­ror.” This al­loy also con­ducts elec­tric­i­ty well, and thus can help pow­er the diode.