A Safer Alternative for the Mercury Beating Heart Demonstration

The mercury beating heart is a classic demonstration to introduce redox reactions in the classroom. Here we report a new, safer demonstration: the Galinstan beating heart. Galinstan is a commercially available eutectic alloy composed of gallium (68.5%), indium (21.5%), and tin (10%) that has low toxicity. When an iron nail touches the Galinstan drop in a sulfuric acid solution, a steady beating heart behavior is observed. The mechanism of the Galinstan beating heart was attributed to electron transfer from the Galinstan drop to the iron nail, which induces a charge redistribution and an interfacial tension gradient on the drop.