STANDARD OPERATING PROCEDURE:
The Thermite Reaction
Note: The Thermite Reaction is an exceedingly dangerous reaction and should only be
performed as a demonstration by trained chemical personnel and experienced
Technicians in conjunction with a current Safety Data Sheet (SDS) and a site-specific
Risk Assessment. The demonstration should be performed outside in a windless area
well away from any other combustibles or flammables.
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1. Introduction
The Thermite Reaction is an excellent example of an exothermic (heat evolving) reaction
involving a metal powder, fuel and a metal oxide. The chemicals undergo a redox
(reduction-oxidation) reaction to form iron metal and aluminium oxide (alumina)
A balanced equation for the reaction is: 2Al + Fe2O3 → Al2O3 + 2Fe
In this reaction iron (III) oxide is reduced to metallic iron by aluminium. It is reported that the
reaction will reach a temperature of about 3000°C, meaning both reaction products are
molten. Thermite reactions have been used for welding metal parts such as railway rails, for
underwater welding and in metal refining.
2. Context
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These instructions are for the use of highly experienced chemistry teachers and
technicians only
Do not attempt this experiment without assistance from an experienced colleague
It is recommended that a trial be performed first using smaller quantities of chemicals
3. Safety notes
This activity has many potential hazards which need to be evaluated;
 For all chemicals consult current SDS’s
 Create a site specific Risk Assessment for the Thermite reaction – see Science ASSIST
web page for a model Risk Assessment
 Check all equipment: flowerpots are free of cracks; glassware is not damaged and is
stress free; sand is dry; the bucket and support stand are sturdy and securely placed;
the fire extinguisher has recently been inspected and tested and is the correct type for
spot fires and chemicals are not out of date.
 It is important to ensure there is no trace of moisture in the reactants or flowerpots as
this could lead to a violent explosive reaction.
 The reaction produces smoke and molten metal sparks and shrapnel which may be
thrown a great distance, therefore students are to be observers only and must stand at
least 5 metres from the reaction
SOP The Thermite reaction Version 1
Written by: Science ASSIST
Disclaimer: ASTA excludes all liability to any person arising directly or indirectly from using this resource.
Date: Oct 2014
Page 1 of 4
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Students should be advised that the molten reaction produces brilliant light
The experiment must always be performed outside in a windless area or at least upwind
As this reaction is highly exothermic and produces molten metal, remove all other
flammable or combustible materials from the demonstration area
A fire extinguisher should be on hand; not for the reaction, but in case of flying sparks
igniting spot fires
Water should not be used to extinguish the reaction, since addition of water to hot iron
produces potentially explosive Hydrogen gas
The demonstrator should not look at the burning Magnesium ribbon, if this ignition
method is used
Once ignition is attained the demonstrator must retreat quickly to at least 5 metres from
the reaction
Since the reaction products will remain red hot for some time, the apparatus must not be
moved until cooled. Cordon off the area until cooled sufficiently and then wearing safety
glasses, use heat-protective gloves to dismantle the apparatus and use tongs to remove
the by-product.
Students, wearing gloves, may handle and inspect the cast iron produced when it is cold
4. Regulations, licences and permits
Not applicable
5. Equipment
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Two new 10cm clay flower pots with drainage holes in base
Small filter paper to fit in the base of one flower pot
Glass rod for mixing the chemicals
Metal trash can or metal bucket ¾ filled with dry sand
Sturdy metal retort stand with metal support ring clamp to hold flower pot (Base may
need weighting)
Perspex safety screen (optional)
PPE for demonstrator: face shield, heat protective gloves, lab coat, closed toe shoes
and long pants
Metal tongs
Safety glasses for student observers standing at least 5 metres away
Correct type of fire extinguisher on hand for spot fires
10g Aluminium metal, fine granular or Aluminium powder
30g Iron (III) oxide powder (Fe2O3)
Gas lighter
Choice of Ignition:
o 18cm strip of Magnesium ribbon
o OR a Sparkler (Firework)
SOP The Thermite reaction Version 1
Written by: Science ASSIST
Disclaimer: ASTA excludes all liability to any person arising directly or indirectly from using this resource.
Date: Oct 2014
Page 2 of 4
6. Operating Procedure
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Stack one clay flowerpot inside the other (During the experiment the inner pot will
crack or shatter but the outer pot will remain in place. Do not reuse this outer pot.
During the experiment the molten iron will drop from the hole of the inner pot.)
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Place the small filter paper in the
bottom of the topmost pot. This
prevents the powder from falling
out the bottom - and it will burn
away during the experiment to
allow the molten iron to flow.
(See adjacent picture)
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Place the aluminium powder and
iron (III) oxide powder in the top
flowerpot and gently stir the
mixture with a glass rod (See
adjacent picture)
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Using the large test tube gently
pack down the mixed powders
(See adjacent picture)
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Place both flowerpots inside the ring clamp and suspend them over the centre of the
container of dry sand to catch the molten iron.
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Select your ignition method:
o Stand an18cm strip of Magnesium ribbon in the chemicals by pushing the
end down through both flowerpot holes and light the top using a gas lighter
o OR. Push the metal handle of a sparkler (Firework) down through both
flowerpot holes including the filter paper so the sparkler stands upright and
the grey sparkler material just touches the chemicals. Light the sparkler using
a gas lighter.
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Once ignition has commenced quickly retreat to at least 5 metres away from
the reaction
SOP The Thermite reaction Version 1
Written by: Science ASSIST
Disclaimer: ASTA excludes all liability to any person arising directly or indirectly from using this resource.
Date: Oct 2014
Page 3 of 4
7. Trouble shooting/emergencies:
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First aid
For chemicals: check current individual SDS’s
Burns: Extinguish any flames, hold burnt area under running water; only remove
clothing if not stuck. Cover with non-adherent burns dressing, plastic wrap or loosely
applied aluminium foil, Do not apply lotions, ointments, any coverings. Call urgent
medical aid.
If inhaled: Remove to fresh air and seek medical attention if symptoms persist.
For further advice contact the Poisons Information Centre on 131 126.
If ignition fails, defer the demonstration and leave the apparatus cordoned off. When
considered safe to do so, carefully examine the mixture of chemicals in the fume
hood.
8. Waste disposal
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Use a commercial waste disposal company to dispose of cast iron
Do not reuse remaining flowerpot for next Thermite reaction demonstration as it has
been stressed and possibly contains unseen cracks
9. Related material
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Videos are available on YouTube. The teacher should review these carefully as there
are various Thermite methods shown using different chemicals and also links to other
dubious, explosive experiments which may not be appropriate for students.
References:
Method: http://www.thecatalyst.org/other/thermite/ accessed October 2014
Photos: http://www.ilpi.com/genchem/demo/thermite/ accessed October 2014
SDS: ‘Iron pieces, irregularly shaped’: http://www.alfa.com/content/msds/Australian/45090.pdf
Australian First Aid Manual, St John Ambulance Australia; 4th edition: 2010
SOP The Thermite reaction Version 1
Written by: Science ASSIST
Disclaimer: ASTA excludes all liability to any person arising directly or indirectly from using this resource.
Date: Oct 2014
Page 4 of 4