Hydrogen gas can produce electricity when it combines with oxygen gas to produce water. Conversely, water can be split into hydrogen and oxygen by applying an electrical current in a process known as electrolysis. Electrolysis is not an economical method of producing hydrogen on a commercial scale. However, you can demonstrate this process with materials from a supplier of chemical equipment.
Obtain a Hoffman voltameter. This device consists of a U-shaped section of glass tubing with an additional section in the middle. The tube in the middle is open at the top and the tubes on the ends have electrodes at the bottom that exit through watertight holes.
Make an electrolytic solution to conduct electricity. A common formula is a solution of 4 parts water and 1 part sodium hydroxide by weight. Mix these reagents in a beaker and stir thoroughly. Pour the electrolytic solution into the middle tube of the voltameter.
Fill a beaker with water. Fill a test tube by completely submerging it in the water. Ensure there aren't any air bubbles in it and turn it upside down without allowing the opening of the test tube above the surface of the water. Suspend the test tube in the water with a test tube holder. Repeat this procedure with a second test tube.
Fill a rubber hose with water and put one end under the surface of the solution in a side tube of the voltameter. Place the other end into an upside-down test tube that you set up in step 3. Repeat this procedure with the other side tube in the voltameter and upside-down test tube from step 3.
Connect the electrodes of the voltameter to a battery and observe the bubbles collecting at the electrodes. The bubbles on the positive electrode are hydrogen and the bubbles on the negative electrode are oxygen. These gas bubbles will rise to the surface and flow through the rubber hoses at the top. As they move into the upside-down test tubes, they will displace the water in the test tubes. Once the test tubes fill with gas, they can be sealed with stoppers for later use.
