Thermit-Reaktion

Eine extrem exotherme Redoxreaktion, bei der flüssiges Eisen aus Rost und Aluminium entsteht

Classroom Demonstrations Advanced (University) 30 Min. ~$15,00

Ziel

Eine extreme exotherme Oxidations-Reduktions-Reaktion demonstrieren, bei der Aluminium Eisenoxid zu flüssigem Eisen reduziert.

Hintergrund

The thermite reaction (2Al + Fe₂O₃ → Al₂O₃ + 2Fe) is one of the most exothermic chemical reactions known. Aluminum reduces iron(III) oxide to produce molten iron and aluminum oxide, reaching temperatures above 2500°C. The reaction is driven by the much greater affinity of aluminum for oxygen compared to iron (the activity series in dramatic action). Thermite is used industrially for welding railroad tracks and cutting through steel.

Sicherheitswarnungen

  • EXTREME CAUTION: Reaction produces temperatures above 2500°C
  • Perform OUTDOORS ONLY with at least 10 m clearance
  • Molten iron droplets are ejected — no one within 5 meters
  • Heavy-duty safety shield is mandatory
  • Have a Class D fire extinguisher on hand (not water or CO₂)
  • Aluminum powder is an explosion hazard — keep away from flame until ready
  • Never attempt to move or disturb the reaction once ignited
  • Wait at least 30 minutes for products to cool before approaching

Erforderliche PSA

goggles gloves lab_coat face_shield

Materialien

  • Iron(III) oxide (Fe₂O₃) powder (50 g)
    Fine rust powder
  • Aluminum powder (15 g)
    Fine mesh (200+)
  • Magnesium ribbon (20 cm)
    Ignition fuse
  • Sand (5 kg)
    Insulation bed

Ausrüstung

Clay flower pot (with drainage hole plugged) Ring stand with iron ring Metal bucket filled with dry sand Safety shield (heavy duty) Fire extinguisher (Class D) Long-handled lighter or match holder

Durchführung

1

OUTDOORS ONLY: Set up the ring stand over the sand-filled bucket. Place the clay pot (with drainage hole plugged with a small wad of paper) on the iron ring.

5 Min. 10 m minimum clearance from buildings
2

Mix 50 g Fe₂O₃ with 15 g Al powder thoroughly (by weight, approximately 3:1 ratio) in the clay pot.

3 Min. No open flames near Al powder
3

Insert the magnesium ribbon into the top of the mixture as a fuse. Ensure the shield is positioned correctly.

2 Min.
4

Ensure all observers are at least 5 meters away and behind cover. Light the magnesium ribbon with a long lighter and retreat immediately.

2 Min. RETREAT IMMEDIATELY after igniting
5

Observe from safe distance: the reaction produces an intensely bright white-orange glow and sparks. Molten iron drips through the pot into the sand below.

3 Min. Do not look directly at the reaction without eye protection
6

Wait at least 30 minutes for everything to cool. Dig through the sand to find the solidified iron button.

10 Min. Products may still be very hot
7

Examine the iron button and white Al₂O₃ slag. Discuss: activity series, enthalpy of formation, why Al is used in thermite (high affinity for O₂), and industrial applications.

5 Min.

Erwartete Ergebnisse

An intensely bright, self-sustaining reaction lasting 10–20 seconds. Molten iron collects at the bottom (a solid metal button when cooled). White Al₂O₃ slag forms on top. The reaction demonstrates the extreme energy difference between Al-O and Fe-O bonds.

Aufräumen

Once fully cooled, collect the iron button and slag. Sand can be reused. Do not pour water on hot products. Dispose of residue in general waste.

Details

Kategorie
Classroom Demonstrations
Schwierigkeit
Advanced (University)
Dauer
30 Min.
Geschätzte Kosten
$15,00
Schritte
7
Materialien
4

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Frequently Asked Questions

What is the objective of Thermit-Reaktion?
Eine extreme exotherme Oxidations-Reduktions-Reaktion demonstrieren, bei der Aluminium Eisenoxid zu flüssigem Eisen reduziert.
How difficult is Thermit-Reaktion?
This experiment is rated as Advanced (University). It takes approximately 30 minutes to complete.
What safety precautions are needed for Thermit-Reaktion?
Key safety precautions include: EXTREME CAUTION: Reaction produces temperatures above 2500°C; Perform OUTDOORS ONLY with at least 10 m clearance; Molten iron droplets are ejected — no one within 5 meters.
What materials are needed for Thermit-Reaktion?
The main materials required are: Iron(III) oxide (Fe₂O₃) powder, Aluminum powder, Magnesium ribbon, Sand.
What results should I expect from Thermit-Reaktion?
An intensely bright, self-sustaining reaction lasting 10–20 seconds. Molten iron collects at the bottom (a solid metal button when cooled). White Al₂O₃ slag forms on top. The reaction demonstrates the extreme energy difference between Al-O and Fe-O bonds.