Electrolysis

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Overview

Some kinds of minerals can be removed from ore through a process called electrolysis. The crushed rock is dissolved in water or other solution and an electrical current is run through the solution to remove the mineral. In this exploration, copper is removed from an "ore" by using carbon electrodes and a battery.

Materials

• Cooper ore is often easy to spot because it can have a green or blue color.

• Since a source of copper-containing isn't readily available, we can use the mineral that has already been removed from the ore. Root killer is a copper mineral called copper sulfate.  This can be found at a hardware or garden store.

• Carbon rods can come from at least two sources: The carbon rod inside an old battery or a pencil carbon.  

• A plastic cup and water

• A 9 volt battery and connector wires. Connectors can be made from hair clips.  

Exploration

• Pour some of the granular root killer (Copper sulfate) into a plastic cup. Add a small amount of water so that the cup is 3/4 full. Stir to dissolve the mineral.

• Connect a carbon rod to each end of the battery connection and place in the solution. See the picture below.

• Allow the electrical flow to work for a few minutes.  Bubbles on one electrode are evidence that the process of electrolysis  is working. Disconnect the battery, remove the rods and examine them.  You should see some color on one carbon rod. This is the copper that has been removed from the solution.

• Use the STEM Notebook to record findings. Include diagrams of the equipment. Indicate the length of time needed for the electrolysis. Draw the carbon rods and write about the nature of the materials using descriptive words of color, size and texture.

Content Background

When any mineral is dissolved in water it forms ions that are free to roam about attached to water molecules.  These ions are either negatively or positively charged and can be influenced by an electrical flow. Copper ions are positively charged and are attracted to a negative pole of the battery.  A full discussion of this action can be seen at http://resources.schoolscience.co.uk/CDA/14-16/cumining/copch2pg4.html   A further explanation of the manner of electrolysis can be seen through this video: https://www.youtube.com/watch?v=IzW0jDuEyIg

Technology of Electrolysis

One crucially important metal we depend upon is aluminum. The only easy way to remove aluminum from its ore (bauxite) is to liquify the ore with lye at extremely high temperatures. After adjusting this liquid mix, gigantic electrical cells are used to attract the aluminum metal to the positive electrode. The industrial process for separating aluminum from its ore can be found here: https://www.youtube.com/watch?v=WaSwimvCGA8

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