Leaching Copper I

In this laboratory activity, copper ions will be dissolved from broken-up copper ore with an acid solution. A variety of acids can be used, with dilute sulfuric acid usually being used in copper mines and most experiments. In this experiment, however, we will be using vinegar (acetic acid). We will heat the vinegar to boiling but you can also use the vinegar at room temperature (this requires more leach time). CAUTION must be exercised in this experiment for this liquid is an acid and is HOT!!!

Materials:

• Copper ore (malachite ore from Nevada) that has been finely crushed
• 100 ml pyrex beaker or pyrex custard cup
• plastic spoon
• 1/2 cup white vinegar heated to boiling (use a sauce pan and electric hot plate)(any vinegar will do but the white vinegar is cheap and clear, which is important later on during the observation of color change.
• A variety of metals such as:
  aluminum wire or foil copper wire steel wire or nail zinc coated nail
  (remember the metal activity series!!!)

Safety:

Remember as with all experiments safety comes first, where possible wear safety glasses and laboratory aprons.

Procedure:

Add a tablespoon of the crushed copper ore to the pyrex container (enough to cover the bottom) and cover with the hot vinegar. Remember, the rock is the ore to be leached, the vinegar is the water solution that leaches the metallic ion out of the ore creating the pregnant solution. The solution will continue to leach metallic ions out of the rock until all the copper has gone into solution. Testing for copper metal ions can begin almost immediately.

NOTE the color of the leaching solution before being added to the ore and the resulting color that appears.

Why does the solution change color?

In order to extract the copper from the solution, we must add a metal to the solution that is MORE REACTIVE than the copper. Add a piece of aluminum wire (3-4 inches long with part of the wire in the solution and part hung over the edge of the beaker). A steel nail, wire or other iron containing material can also be used. A piece of copper wire can be used as a control to demonstrate what happens to copper containing materials in the reaction.

After a few minutes remove the aluminum wire from the solution. Has anything happened to the wire? Describe what has happened.

Place the aluminum wire back into the solution and check after 1/2 hour. Has any change occurred? Describe what has happened.

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Please direct questions to: Tom Lugaski
Last Modified May 20, 1997
Copyright University of Nevada, Reno 1996