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

  1. Add 0.5 M copper(II) chloride solution into a beaker.
  2. Cut a piece of aluminum foil and loosely crumple it so it will fit in the beaker.
  3. Place the foil into the solution, using a stirring rod to submerge it fully.
  4. Observe the reaction: bubbling gas, strong heating, fading of the green-blue solution, and formation of reddish-brown copper metal.
  5. Test the gas released with a lit splint (hydrogen gives a “pop”) or with a glowing splint (no re-ignition; confirms no oxygen).
  6. 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).
  7. Allow the solid copper to settle and decant the liquid for safe disposal.

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)