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Me08 Reaction of two metals of a Cola can with acid and with copper salt
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Attention!
Hydrochloric acid is corrosive. Do not forget your goggles. Work on a trash.
What you
need: Cola
can (recycling icon FE), scissors, sand paper, blister packing, dropper
bottle with hydrochloric acid (10%) and diluted copper salt solution.
* Left: Sandpaper
the closure and an piece of piece of sheet metal cut from a Cola can.
* Middle: Transfer
1 ml of Acid to each of the left blisters and 1 ml copper salt solution
to the right ones.
* Dip a stripe of the closure
(Al) into each of the upper blisters and a piece of sheet metal (Fe) to
the lower ones.
* Observations
right:
In Acid vigorous gas formation of with Al, only week with Fe.
* In bue copper salt
solution
both metals cover with a copper brown layer.
* The blue colour disappears
in both solutions.
Explanations:
The
metal atoms aluminium (Al) and iron (Fe) are electron
donors, the H+(aq) and the blue Cu2+(aq)
are electron acceptors.
There
are direct redox reactions:
Metal
atoms (Me) and the positive ions (I+) are in direct contact
while electrons (e- ) are exchanged: Me--(e- )-->(I+).
The
ions are reduced, resulting in hydrogen gasand copper, the metal atoms
are oxidized leaving ions:
2 Al + 6 H+(aq)
---redox---> 2 Al3+(aq)
+ 3 H2(g) (left blister)
Fe + 2 H+(aq)
---redox---> Fe2+(aq)
+ H2(g)
2 Al + 3 Cu2+(aq)
--redox--> 2 Al3+(aq)
+ 3 Cu(s) (right
blister) Fe + Cu2+(aq)
---redox---> Fe2+(aq)
+ Cu(s)
The electrons are more
easily released by aluminium than by iron atoms. Al was more reactive in
the experiments.