Aluminum vs. Salt
What can “eat” aluminum in seconds?
Wear protective gloves, eyewear, and a mask. Perform this experiment in a well-ventilated area.
Reagents and equipment
- 50g copper(II) sulfate pentahydrate;
- 100g sodium chloride;
- 100mL distilled water;
- a foil cupcake liner;
- a glass that fits the liner.
Set the cupcake liner in the glass, then measure 50g copper(II) sulfate into it. Add 100mL distilled water and 100g sodium chloride. Watch as the solution turns green. 5 minutes later, observe the formation of a reddish-brown precipitate and rapid corrosion of the aluminum liner.
Aluminum is an active metal, but it is covered with a strong oxide film and therefore is quite inert. However, in the presence of sodium chloride and copper(II) sulfate, the oxide film is destroyed. This allows aluminum to interact with the water molecules, releasing colorless hydrogen gas:
2Al + 6H₂O = 2Al(OH)₃ + 3H₂
Aluminum also displaces copper ions from the solution:
2Al + 3Cu²⁺ = 3Cu + 2Al³⁺