Inorganic reactions
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What are the ideal conditions for reacting magnesium and steam and what is the setup like?
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Do not do this experiment yourself. It should only be done as a demonstration by your teacher. Always do a risk assessment before doing practical work.
The problem with this reaction is that you need to get the magnesium very hot get the reaction to go. Also the surface of the magnesium gets coated with an oxide layer which prevents the reaction starting. The easiest way around this is to start the metal burning in air and then to pass steam over the burning metal. This can be done in a test tube as a demonstration.
The set-up
The basic arrangement is to clamp a large test tube at an angle with torn-up filter papers or ceramic wool soaked in water at the bottom.
There is a coil of clean magnesium ribbon in the middle of teh tube.
The demonstration
Taking suitable precautions, the demonstrator first heats the tube next to the metal until the magnesium just starts to burn. At this point warming the bottom of the tube produces a flow of steam which reacts vigorously with the hot metal.
It is sometimes possible to show that the reaction produces a gas which burns. This is hydrogen.
Much of the magnesium turns white. The white product is magnesium oxide.
The glass next to the metal turns black. This is because some of the hot magnesium reacts with silicon dioxide in the glass forming silicon.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 07 November 2003
