CONCEPTS: Chemical reactions, elements, metals, reactivity, ions, energy 
BACKGROUND: Metals are elements that may react by losing electrons to form ions.  
The ions of some elements (in water solution) react with elemental metals to produce 
the metal from the ion and vice versa.  
Metals: Iron (nails), copper (wire, pennies), aluminum (foil) 
Compounds: Copper sulfate (solution), salt, vinegar 
PREPARATION: Concentrated solution of copper sulfate: 
add 4 - 5 teaspoons of copper sulfate to one cup of water. 
1. Clean a penny: place a penny in vinegar--becomes shiny as oxide on surface reacts 
with acid and dissolves. 
2. To show that copper is in the solution from #1, put 50 pennies in a cup of vinegar 
and let stand all day or overnight.  
The next day, place iron nail in solution.  Iron metal reacts with copper ions in solution—
copper metal appears on nail. 
More dramatic: dip iron nail into concentrated solution of copper sulfate.  
3. Different metal--more reactive.  
Repeat with galvanized nail--zinc is more reactive--faster reaction. 
4. Zinc and acid (vinegar)--zinc ions produced as zinc dissolves (in solution) 
and elemental hydrogen gas produced. 
5. More dramatic: Add a pinch of salt to some concentrated copper sulfate solution.  
Add a small piece of aluminum foil.  
Rapid reaction produces copper and hydrogen. (and heat!) 
CONNECTIONS: Some metals are more reactive than others--iron, aluminum, 
and zinc are found in nature only as compounds.  
Copper and gold may occur as "native" elements.  
Acids are used to remove oxide coating on metals eg. in steel mill.