How to Make a Machine to Separate Hydrogen & Oxygen in Water
Water is composed of one atom of oxygen and two atoms of hydrogen. You can separate water into hydrogen and oxygen gas by running an electrical current through the water. The energy from the electricity splits the covalent bonds between the hydrogen and oxygen atoms in a process called electrolysis. This experiment is commonly performed in college chemistry classes.
Things You'll Need
- Water
- Sodium hydroxide
- 3 beakers
- Hoffman voltameter
- 2 Test tube holders
- 2 Test tubes
- 2 Rubber hoses
- 9V Battery
- 2 wires
- 2 Test tube stoppers
Instructions
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1
Set up the Hoffman voltameter. This glass apparatus consists of a U-shaped piece of glass tubing that's open at the ends. A second glass tube is open at the top and connected to the middle of the "U". This results in three vertical tubes that are open at the top and joined at the bottom by a horizontal tube. The left and right tubes have wires called electrodes at the bottom that exit the tubes through watertight seals.
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2
Make a sodium hydroxide solution by thoroughly mixing four parts water and one part sodium hydroxide. This solution will allow the water to conduct electricity and is therefore called an electrolyte. Fill the Hoffman voltameter by pouring the electrolyte into the middle tube.
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3
Fill two beakers and two test tubes with water. Hold your thumb over a test tube, invert it and place into a beaker so that the test tube is upside down and filled with water. Fix the test tube in place and repeat this procedure with the other test tube and beaker.
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4
Connect one end of a rubber hose to the open end of the left tube of the Hoffman voltameter. Place the other end into one of the test tubes. Repeat this procedure with another rubber hose and the right tube of the Hoffman voltameter.
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5
Attach each electrode to one of the battery terminals and you should see bubbles forming on both electrodes. The bubbles on the negative electrode are hydrogen and the bubbles on the positive electrode are oxygen. These bubbles will pass through the rubber hoses and fill the test tubes by displacing the water. You may stopper the test tubes for later use once they're filled with hydrogen and oxygen.
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