Magnesium and Steam Reaction

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Chemical Reactions, Oxidation and Reduction

Alternative titles: Hydrogen Production from Magnesium and Steam

Summary

When magnesium is heated strongly in the presence of steam, it reacts to form magnesium oxide (a white solid) and hydrogen gas.

Procedure

Refer to below links for method.

Links

The reaction of magnesium with steam | Demonstrating the reactivity series & displacement reactions - Royal Society of Chemistry:

Reaction of Magnesium with Steam - Rugby School Chemistry:

Variations

Compare magnesium’s reaction with cold water, hot water, and steam to illustrate the effect of temperature.

Safety Precautions

Wear goggles and a lab coat; magnesium burns with an intense light—avoid looking directly at it.
Use heatproof gloves and tongs to handle hot glassware.
Hydrogen gas is flammable; ensure good ventilation and keep away from open flames except during controlled splint testing.
Ensure the combustion tube is heat-resistant and securely clamped.
Do not touch magnesium oxide residue until the apparatus has cooled.

Questions to Consider

Why does magnesium react only slowly with cold water but rapidly with steam? (Cold water produces insoluble magnesium hydroxide that coats the metal; steam supplies higher energy and avoids this passivation.)
What is the balanced chemical equation for magnesium reacting with steam? (Mg + H₂O → MgO + H₂)
What type of reaction is taking place? (Redox reaction: magnesium is oxidized, hydrogen ions are reduced.)
Why does magnesium form an oxide with steam instead of a hydroxide? (Hydroxides decompose at high temperatures to oxides and water.)