Chemistry in Pictures: Mercurial heart

This is one heart you don’t want to wear on your sleeve—because it’s made of liquid mercury. Daniel Stribling, now a graduate student at the University of Florida, and Christopher Brewer, now a postdoc at the University of Texas at Dallas, recorded this video of a “mercury heart” demonstration that they set up as undergraduate students at Florida State University. The demo starts with a pool of liquid mercury, about 2.5 cm in diameter, in an acidic solution containing hydrogen peroxide, which causes the surface of the metal to oxidize from mercury(0) to mercury(II). The oxidation reduces the surface tension, so the mercury flattens and and spreads out. As it spreads out, the pool runs into an iron nail suspended nearby, which reduces it back to Hg(0). When that happens, the mercury contracts, breaking contact with the nail, and enabling oxidation to restart. The mercury blob usually settles into a triangular shape that vaguely resembles a beating heart, but it can also take the shape of a pentagon or hexagon if conditions are right.

Submitted by Daniel Stribling

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