Repetitive Deformation of Ga-Based Liquid Metal in Acidified CuCl₂ or FeCl₃ Solution

In chemical education, repetitive and large-scale motion of material in a chemical reaction could effectively capture students’ attention and stimulate their interests to further explore the underlying science. Gallium-based liquid metals are more safe and suitable for some classroom demonstrations than mercury to introduce chemical principles. In this article, we describe a visually striking experiment using Ga-based liquid metal. Repetitive and large-scale deformation of liquid metal was observed in an acidified solution of either copper(II) chloride or ferric(III) chloride. To elucidate the mechanism of deformation, the chemical reaction and the interfacial tension are discussed. Deformation can be attributed to a spatial and temporal imbalance of the interfacial tension on the liquid metal induced by the chemical reactions. The simple setups and readily available chemicals enable this experiment to be a suitable and safe classroom demonstration.