Electrodes

Inexpensive Electrodes

Most commercially available devices that transmit an electrical current through aqueous solutions make use of platinum wire. The price of platinum is such that more than half of the cost of the device is in that platinum alone. This makes platinum far beyond the budgets of most precollege institutions. So what can be done?

Happily, there is a solution! Carbon rods such as found in automatic pencil lead or in the interior of ordinary wooden pencils. Long ago pencils did contain the metal lead, and you may wish to "play" and not that by rubbing a piece of lead-solder across paper, a gray line is formed. That is the historic pencil. Today pencils contain graphite mixed with clay. Fortunately for our impecunious teaching-lab budgets carbon conducts electricity and is relatively inert for our purposes which involved some level of electrolysis.

If you need pencil lead that is thicker than found in that sold for mechanical pencils, you may decide to extract the lead from a wooden pencil. This can be done by boiling the pencil in water for awhile to cause the two pieces of wooden sheathing to come apart. If you boil "primary" pencils - those often used by little children, you will obtain rather thick rods of pencil lead. (Note: If you want to make any of the devices for electrolysis, and need to insert the carbon rods through rubber grommets, you should use the largest diameter pencil leads that you can find, since many hardware stores don't sell grommets of very small diameters. Most primary pencils are too narrow. Furthermore, many pencils do not readily fall apart with boiling. However, Staples sells larger ones: "My First" Ticonderoga #2", which do fall apart with boiling once the eraser has been cut off with a hacksaw or other small saw. A little prying with a small screwdriver helps. Further helps: removed some of the paint so that the hot water can penetrate the wood - use either acetone, coarse sandpaper or a file. A pressure cooker is better than boiling.)

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