How to make an alloy that resembles mercury
Experiments with an alloy made from indium and gallium
Wear protective gloves.
Reagents and equipment
- a Petri dish;
- a plastic vial with a cap;
- an LED and power source;
- a cotton swab;
- a syringe.
Rub the gallium and indium against each other over the Petri dish. Notice that the metals dissolve in one another. Transfer a few drops of the resulting alloy into the plastic vial, cap it, and shake. Observe the formation of a metallic “mirror.” Use the cotton swab to draw an unbroken line through the Petri dish. Use this line to close an electrical circuit with an LED diode – the diode should light up.
Indium and gallium form an alloy consisting of 75.5% gallium and 24.5% indium, often called a gallium indium eutectic alloy. Its main advantage lies in its melting point, 16 °С (61 °F), which makes it a prospective replacement for the dangerous mercury in devices such as thermometers. It also coats surfaces well, including plastic surfaces, forming a “metallic mirror.” This alloy also conducts electricity well, and thus can help power the diode.