Gallium Metal

Gallium Metal: Hi, I was wondering what your thoughts were on the use of gallium in schools (Years 7–12) for the purpose of demonstrating the melting point of metals and possibly other experiments. Is it considered safe for students to handle assuming they're wearing gloves?

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Publication Date: 13 January 2015
Asked By: Anonymous
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Metal

Answer reviewed 23 February 2023

From the available information, metallic gallium can be safely stored, managed and used within a school science environment. From a curriculum perspective, it provides an excellent example of metal properties demonstrating low melting point (29.8 °C), metallic lustre, and high density (5.9).  Gallium is a much safer alternative to mercury as an example of a low melting point metal as it is regarded as comparatively non-toxic.

Gallium is not a commonly used element therefore the body of knowledge of its properties is not as extensive as for more common metals.  Therefore, Science ASSIST recommends that a site-specific risk assessment be conducted before use, and that gallium is used as a teacher demonstration due to the high cost of this element.

Gallium is insoluble in water and unlikely to be absorbed by the skin during handling. There are some reports of skin sensitivity leading to dermatitis so,as stated on the SDS, wearing nitrile gloves is recommended.  Eye protection should also be worn.

At room temperature, there is no inhalation hazard and the metal is non-corrosive to plastics.  It is considered corrosive to metals, so contact with metals, especially aluminium and aluminium alloys, should be avoided. Some gallium compounds are known to be toxic and contact of the metal with strong acids, strong bases, oxidising materials and halogens should be avoided.

Spills can be cleaned up by pouring ice water over the spill to freeze the gallium, which can then be scooped up with a spatula. Gallium is electrically conductive, so any spills into or onto powered equipment need to be treated with caution. If gallium is spilt on electrical equipment, the power must be switched off before attempting to clean it up.

Storage

Gallium is best stored in its original container.  Gallium expands and contracts with temperature change meaning storage in a glass or metal container is not recommended. If repackaged, it can be safely stored in a polyethylene container.   Storage in the fridge (2–8 °C), is also recommended, as the metal will remain solid, which minimises its absorption of oxygen from the air and therefore slows its rate of oxidation. 

Activities

A simple demonstration of the low melting point of gallium is performed by holding gallium and allowing it to melt in the hand; wearing nitrile gloves is necessary for this demonstration.  Used gloves can be disposed of in general waste.

Gallium is the metal used in the classic “disappearing teaspoon” demonstration.  The references below include video clips of this activity, additional information and overseas sites offering gallium and silicone rubber moulds for recasting spoons from the molten metal.  A risk assessment of this activity must include steps to ensure that the stirred liquid is not ingested, and that the gallium spoons do not come into contact with foods.

Availability and price

Unfortunately, gallium is a very expensive substance, and its cost is likely to be prohibitive to schools.  It could perhaps be considered for demonstration purposes.  There are several reasons for this high cost.

  • Gallium is a very uncommon low-use element.
  • Because of its use in electronics, gallium is available only in very high purity, with the lowest available grade being 99.99%.  This increases the cost.
  • Gallium is a Class 8 Dangerous Goods (UN 2803) and is thus very expensive to transport and import.  Our advice from importers of chemicals is that, even for the online purchase of gallium from overseas suppliers, such as those given in the references below, there would be added transport and import costs.

Science chemicals wholesale company Sigma Aldrich gives the following retail prices (as of February 2023) for 99.99% pure gallium:

  • 50 grams—$658
  • 10 grams—$218

These prices would not include GST or the extra costs of delivery to school sites.

References

Chem Survival. (2020, April 23). The disappearing spoon demonstration (how to make one and how it works) [Video]. YouTube https://youtu.be/8QhUtLxeFL4 

Foley, N. and Jaskula, B. 2013, Gallium—A smart metal: U.S. Geological Survey Fact Sheet 2013–3006, 2 p., https://pubs.usgs.gov/fs/2013/3006

Rotometals. (nd), Gallium Disappearing Spoon Mold -Create a Magic Disappearing/Bending/Melting Gallium Spoon, Includes Syringe. Retrieved (23 February 2023) from the Rotometals website: https://www.rotometals.com/gallium-disappearing-spoon-mold-create-a-magi...

Sigma-Aldrich. 2021. Gallium, Safety Data Sheet. Search https://www.sigmaaldrich.com/australia.html to source the latest Safety Data Sheet via the product information page.

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