#10: Shapeshifting Gallium

Of the many fascinating chemicals that I have recently obtained, I have a favorite. It is a shiny low-melting metal called gallium. While you may not have heard of it, gallium is actually the 31st element on the periodic table, located just below aluminum. It has quite a few interesting traits, some of which I plan to explore in future experiments. Gallium is best known for its relatively low melting point of 86 degrees Fahrenheit. This, along with the fact that it is also non-toxic, makes it a great substitute for mercury. In general, liquid metals have many unique properties. Unfortunately, because most metals have extremely hot liquid states, they can't react with other fluids without instantly solidifying. This makes gallium useful in examples of aqueous chemistry such as my most recent experiment. 

I started by placing a small piece of my gallium into a beaker with some water. After heating the beaker for a short time, the metal melted into an irregular blob. Next, I added a few drops of concentrated sulfuric acid (H2SO4). Within seconds, the liquid gallium became a perfect sphere. This was because the newly formed gallium sulfate had a higher surface tension than the metal by itself. In the second part of the experiment, I reversed this effect by adding a small amount potassium permanganate (KMnO4). Just like the sulfuric acid, the permanganate changed the chemical composition of the gallium. However, instead of increasing the metal's surface tension, it lowered it. This caused the gallium to spread out like oil slick. The interesting part came when I poured in more sulfuric acid. This reversed the reaction once again as it caused the layer of gallium to form beads.

Ideally, this is supposed to be an oscillating reaction in which both chemicals are balanced. In this situation, the gallium would constantly contract and relax as the chemicals on its surface changed places. This unique behavior of the gallium is why the demonstration is often called the "gallium beating heart experiment." The process is significant because it shows that by changing a liquid's chemical makeup, you can change its surface tension and thus, the way it behaves.

While the experiment didn't go entirely as planned, the gallium behaved in some interesting ways.

To see the true gallium beating heart experiment...

http://www.youtube.com/watch?v=N6ccRvKKwZQ