How To Do the Gallium Beating Heart Demonstration

The gallium beating heart is a chemistry demonstration in which a drop of gallium is made to pulsate, like a beating heart. The gallium beating heart is similar to the mercury beating heart, but gallium is much less toxic, so this demonstration may be preferable. Unlike the mercury beating heart, no iron is required to perform this demo, though the gallium heart beats more slowly. Although performing the demonstration is fairly straightforward, it can be tricky to add the proper proportions and correct amount of dichromate to get the gallium to pulsate. For this reason, start with a small amount of the chemical and add more as needed. Materials Needed Drop of gallium metal, liquefied (apply heat, as from your gloved hand)Dilute sulfuric acid (for example, battery acid)Potassium dichromateWatch glass or petri dish Directions Place a drop of liquid gallium in a shallow dish.Cover the gallium with dilute sulfuric acid. The drop will round into a ball as gallium sulfate forms on the surface of the drop.Add a small amount of potassium dichromate. The gallium will relax somewhat as the sulfate layer is removed and the surface tension of the drop changes. If the proportion of dichromate with respect to the sulfuric acid is just right, the drop will alternate between round and relaxed, like a beating heart.