demonstrations:aluminum_and_copper_chloride_redox_reaction
Aluminum and Copper(II) Chloride Redox Reaction
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★☆ Some safety precautions required to perform safely
Categories: Oxidation and Reduction
Alternative titles: Foiled Again
Summary
When aluminum foil is added to copper(II) chloride solution, a vigorous redox reaction occurs in which aluminum displaces copper from solution, forming aluminum chloride, metallic copper, hydrogen gas, and a noticeable release of heat.
Procedure
- Add 0.5 M copper(II) chloride solution into a beaker.
- Cut a piece of aluminum foil and loosely crumple it so it will fit in the beaker.
- Place the foil into the solution, using a stirring rod to submerge it fully.
- Observe the reaction: bubbling gas, strong heating, fading of the green-blue solution, and formation of reddish-brown copper metal.
- Test the gas released with a lit splint (hydrogen gives a “pop”) or with a glowing splint (no re-ignition; confirms no oxygen).
- Compare with control tests by placing aluminum foil into copper(II) sulfate solution (no reaction), sodium chloride solution (no reaction), or both together (reaction occurs due to chloride complexation).
- Allow the solid copper to settle and decant the liquid for safe disposal.
Links
Foiled Again - FlinnScientific:
Aluminum and Copper (II) Chloride Reaction - Bond with James:
📄 Foiled Again — Aluminum Loses
to Copper - Flinn Scientific: https://www.flinnsci.ca/api/library/Download/7202c51528a240ec81e731e2142c53c4
Variations
- Try using different shapes or surface areas of aluminum foil to see how reaction rate changes.
Safety Precautions
- Wear chemical splash goggles, chemical-resistant gloves, and a protective apron.
- Copper(II) chloride is toxic; avoid ingestion and skin contact.
- The reaction produces hydrogen gas, which is highly flammable; keep flames away and perform in a well-ventilated area.
- The reaction is exothermic; the beaker may become hot to touch. Handle with care.
- Dispose of solutions and solids according to hazardous waste guidelines; do not pour copper solutions directly down the drain unless allowed by local regulations.
Questions to Consider
- Write the balanced equation for the main reaction. (2Al + 3CuCl₂ → 2AlCl₃ + 3Cu)
- Which element is oxidized and which is reduced? (Aluminum is oxidized to Al³⁺; copper(II) is reduced to Cu metal)
- Why does hydrogen gas form as a side reaction? (Because the solution is slightly acidic, allowing H⁺ ions to react with aluminum)
- How does the surface area of the aluminum foil affect the rate of reaction? (Greater surface area increases reaction rate)
- Why does aluminum not react with copper(II) sulfate alone? (Chloride ions are needed to break through aluminum’s oxide layer and catalyze the reaction)