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Gallium is an unusual metal. It does not occur as a pure element in nature, but can be purchased in pure form to be used for some truly amazing science demonstrations. One of the most popular gallium demonstrations is melting gallium in the palm of your hand. Here's how to do the demonstration safely and the explanation for how it works.
Melted Gallium Materials
Basically, all you need for this project is a sample of reasonably pure gallium and your hand:
- Pure gallium
- Plastic gloves (optional)
You can buy a chunk of pure gallium for around $20 online. It's safe to use your bare hand for this experiment, but gallium has two properties that may make you wish to wear a pair of disposable gloves. First, gallium metal wets both glass and skin. What this means is the melted metal will leave finely divided gallium particles on your skin, giving it a grayish cast. It's not super-easy to wash off, so you might want to avoid the issue. The other consideration is that gallium attacks other metals. So, if you usually wear a ring, you may want to wear gloves just to make certain no gallium or leftover metal is available to discolor your jewelry.
How to Melt Gallium
What could be easier? Simply place the piece of gallium in the palm of your hand and let the warmth of your body heat do the work! The melting point of gallium is 29.76 C (85.57 F), so it will readily melt in your hand or in a very warm room. Expect this to take around 3-5 minutes for a coin-sized piece of metal.
When you are done examining the gallium, tilt your hand to allow the metal to flow into a non-metal container. If the container is also warm, the slow cooling will allow you to watch gallium form metal crystals.
You can supercool gallium, which is holding it as a liquid above its freezing point. Do this by pouring the liquid gallium into a warm container and keeping it free of vibrations. When you are ready to crystallize the metal, you can jar the container, touch the sample, or seed crystallization by adding a small piece of solid gallium. The metal exhibits an orthorhombic crystal structure.
Points To Keep in Mind
- Gallium may temporarily discolor your skin. This is because it wets skin. Keep in mind this means you'll lose a tiny bit of your sample every time you do the demonstration.
- Some people have reported mild dermatitis (redness, itching, inflammation) from long-term gallium exposure to skin. Basically, this means you should wash your hands after the conclusion of the demonstration.
- Gallium is not toxic. It is used in pharmaceuticals, so you could probably swallow it and be okay, but it's not recommended, plus it would be an expensive snack.
- Gallium attacks other metals, so do not let it come into contact with jewelry or store it in metal containers.
- Gallium expands as it cools, so it usually kept in a plastic bag or flexible container rather than glass to avoid any possibility of expansion shattering the container. Also, gallium wets glass, so storing in plastic helps minimize sample loss.
Other Elements That Would Melt in Your Hand
Gallium is not the only metal that melts into a liquid near room temperature or body temperature. Francium, cesium, and rubidium also would melt in the palm of your hand. However, you seriously don't want to attempt this demonstration with any of them! Francium and cesium are radioactive. Cesium and rubidium react vigorously with water, which basically means they could set your hand on fire. Stick with gallium.
Learn More About Gallium
If you have gallium to melt in your hand, you may also wish to try the melting spoon trick. In this science magic trick, you either melt a gallium spoon with what appears to be the power of your mind or else you make it seem to disappear in a glass of hot water. Gallium is an interesting metalloid, so you may wish to learn more about the element.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Strouse, Gregory F. (1999). "NIST realization of the gallium triple point". Proc. TEMPMEKO. 1999 (1): 147-152.