"Battle of metals" experiment

Aluminum foil Vs. Copper(II) sulfate

In chem­istry, just like in life, there is con­stant com­pe­ti­tion. Some met­als force oth­ers out of their bonds. In this col­or­ful ex­per­i­ment, we show you the main rule of dis­place­ment of met­als based on the ex­am­ple of the “bat­tle” be­tween alu­minum and cop­per.

Reagents and equip­ment:

  • alu­minum foil;
  • cop­per(II) sul­fate;
  • sodi­um chlo­ride;
  • dis­tilled wa­ter;
  • beaker.

Step-by-step in­struc­tions

First make a small cup out of alu­minum foil and place in on the beaker. Then pour a blue so­lu­tion of cop­per(II) sul­fate and a trans­par­ent so­lu­tion of sodi­um chlo­ride into this cup. The so­lu­tion turns green. Af­ter a few sec­onds, a vi­o­lent re­ac­tion will start to take place, with the re­lease of gas and a red-brown sed­i­ment on the sur­face of the alu­minum foil. Grad­u­al­ly, the lay­er of alu­minum foil dis­in­te­grates, and the re­main­ing so­lu­tion drips through the hole that ap­pears.

Pro­cess­es de­scrip­tion

Alu­minum does not re­act with the so­lu­tion of cop­per sul­fate, as its sur­face is pro­tect­ed with a durable ox­ide film. When the so­lu­tions of cop­per(II) sul­fate and sodi­um chlo­ride are mixed, the com­plex salt of cop­per(II) chlo­ride forms, which turns the so­lu­tion green.

Cu­SO₄ + 4Na­Cl ⇆ Na₂[Cu­Cl₄] + Na₂­SO₄

Chlo­ride ions can de­stroy the ox­ide film, as a re­sult of which the alu­minum starts to in­ter­act si­mul­ta­ne­ous­ly with cop­per cations and wa­ter mol­e­cules:

2Al + 6H₂O → 2Al(OH)₃ + 3H₂

3Cu²⁺ + 2Al → 3Cu + 2Al³⁺

Alu­minum forces the cop­per out of the bond, as alu­minum is a more ac­tive met­al than cop­per in the elec­tro­chem­i­cal se­ries of met­als. Thus, red metal­lic cop­per and gaseous hy­dro­gen are re­leased. This re­ac­tion takes place very in­ten­sive­ly, and with the re­lease of heat.

Safe­ty pre­cau­tions

Be­fore con­duct­ing the ex­per­i­ment, put on rub­ber gloves and pro­tec­tive glass­es.

Warn­ing! Sub­stances of this ex­per­i­ment are tox­ic and high­ly dan­ger­ous for your health. Do not try this at home. Only un­der pro­fes­sion­al su­per­vi­sion.

Try it