Activity: Copper refining

Nicholas and the copper coated nail.

On SCOPE's Mining episode, you saw Nick extract copper metal from some home made copper ore. Here's how he did it:

CAUTION: This activity uses copper sulphate, which is mongst other things a chemical used in gardening. You should wear eye and hand protection when using copper sulphate and do not use kitchen cups or spoons.

What you need

• Copper Sulphate
• Sand
• An old container
• An old jar
• A plastic cup
• 2 stainless steel nails
• A battery
• 2 alligator clips

What to do

1. To make the copper "ore", add ¼ of a cup of copper sulphate and 2 cups of sand into the container.
2. Add in enough water to make a slurry and mix.
3. Let the mix stand for about 5 minutes, so that the sand settles to the bottom.
4. Pour off some of the blue liquid into the jar.
5. Attach the nails to the battery with the alligator leads and put them in the liquid so that the liquid comes about half way up.
6. Pretty soon copper will be plating out onto one of the nails.

What's happening?

If you've ever wanted to do some mining, but didn't have a gigantic truck handy then this experiment is for you!

When copper is mined it doesn't come out of the earth in big lumps (although copper can be found in its native form, it is rare). Instead, it is usually extracted from dug up copper ore and then plated out into big sheets of pure copper.

This experiment is a scale version of the process, although the "ore" isn't the same as that which is dug up at a mine.

The water dissolves the copper sulphate, and other minerals in the sand, so when it is strained off, the copper is now in the water. By putting an electrical current through the blue solution, the copper is plated out at the cathode (nail attached to the negative battery terminal).

The reaction is: Cu²⁺+ 2 e^- ---> Cu (s)

At the same time, bubbles will stream from the other nail, this is a reaction that balances the copper production and is water turning into Hydrogen ions and Oxygen gas.

That reaction is H₂O ---> 2H + + ½ O₂(g) + 2 e^-

At copper refineries the copper is plated out onto big metal sheets instead. So although you mightn't end up with as much as that, either way you still get genuine, pure copper!