Copper Oxide and Zinc Displacement 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: Zinc Reduces Copper Oxide

Summary

When a mixture of copper(II) oxide and zinc powder is ignited, zinc reduces copper oxide to copper metal while itself being oxidized to zinc oxide. The exothermic reaction releases enough heat to make the products glow and sometimes melt.

Procedure

Mix small amounts of powdered copper(II) oxide (black) and zinc powder in a heat-resistant container such as a crucible.
Place the container in a fume hood or well-ventilated area with a heat shield.
Use a flame to supply activation energy to one spot in the mixture.
Observe as the reaction spreads through the mixture, releasing bright light and intense heat.
Note color changes: copper oxide (black) turns into zinc oxide (yellow-hot, white when cool) and copper metal (red-brown, may glow).
Allow the reaction to cool completely.
To confirm copper, add dilute hydrochloric acid to dissolve zinc oxide and excess zinc, leaving copper metal behind.

Links

Reaction between zinc and copper(II) oxide - chemistry edb:

Displacement reaction of zinc and copper(II) oxide - Andy's Chemistry:

Variations

Try initiating with a magnesium strip fuse to make ignition safer.
Demonstrate alongside a classic aluminum-iron oxide thermite for comparison of energy release.

Safety Precautions

Wear safety goggles, heat-resistant gloves, and a lab coat.
Perform behind a safety screen; the reaction is highly exothermic and may spatter molten material.
Handle zinc powder with care; it is flammable in fine form.
Do not look directly at the bright reaction for long periods to avoid eye strain.
Hydrochloric acid is corrosive; handle with care and neutralize spills promptly.
Allow crucible and products to cool fully before handling.

Questions to Consider

What type of reaction is this? (A single displacement redox reaction)
Which element is oxidized and which is reduced? (Zinc is oxidized to Zn²⁺; copper is reduced to Cu metal)
Why does the reaction release so much heat? (The formation of zinc oxide is highly exothermic, driving the process)
How can you confirm that copper has been formed? (By dissolving zinc oxide and excess zinc with dilute hydrochloric acid, leaving copper behind)
How is this reaction similar to and different from a thermite reaction? (Both are highly exothermic metal-oxide reductions; this one produces copper instead of iron and can be done on a smaller scale)