Thermite Spheres
Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★☆ Some safety precautions required to perform safely
Categories: Chemical Reactions, Oxidation and Reduction
Alternative titles: Safe Thermite Reaction, Microscale Thermite Reaction
Summary
Two rusty iron spheres wrapped in aluminum foil are struck together to initiate a redox reaction. The reaction releases energy in the form of a popping noise and sparks, demonstrating the principles of thermite chemistry in a controlled and safe way.
Procedure
- Obtain two rusty iron spheres.
- Strike the spheres together without foil to show that no reaction occurs.
- Wrap both spheres with a layer of aluminum foil.
- Strike the foil-wrapped spheres together firmly.
- Observe the loud popping sound and sparks, especially visible in a darkened room.
- Inspect the spheres to show that rust has been reduced to iron and the aluminum has been oxidized.
Links
Microscale Thermite Reactione - Harvard Natural Sciences Lecture Demonstratrions:
📄 (Safe) Thermite Reaction (On page 5) - Author: https://www.unco.edu/nhs/science/pdf/demos/2005_CSC.pdf
Variations
- Use different degrees of rust on the spheres to see if reaction intensity changes.
- Compare the reaction with a true thermite mixture (iron oxide + aluminum powder) for students at an advanced level.
Safety Precautions
- Safety glasses and gloves must be worn at all times.
- Perform away from flammable materials.
- Do not allow students to strike the spheres themselves; only an instructor should handle them.
- Ensure that spectators are kept at a safe distance.
Questions to Consider
- What is being reduced and what is being oxidized in this reaction?
- Why does aluminum replace iron in the reaction?
- How does this “safe thermite” compare to a traditional thermite reaction in terms of energy release?
- Why is rust (iron oxide) required for the reaction to occur?
- What does the spark and popping sound reveal about the energy released during the reaction?