How to Make Hydrogen Gas
Hydrogen is the most common element in the universe and is a gas under standard conditions. However, there is very little hydrogen gas in the atmosphere, as the Earth's gravity is insufficient to hold on this extremely light element. You must therefore obtain hydrogen from some hydrogen-containing compound. You can use an electrical current to split water (H2O) into hydrogen and oxygen gas in a process known as electrolysis.
Things You'll Need
- Water
- Sodium hydroxide
- 3 Large beakers
- Hoffman voltameter
- 2 Test tube holders
- 2 Test tubes
- 2 Rubber hoses
- 9V Battery
- 2 Test tube stoppers
Instructions
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1
Make a solution of sodium hydroxide. Mix four parts water and one part sodium hydroxide by weight in a beaker and stir thoroughly. The purpose of the sodium hydroxide is to allow the water to conduct electricity, so this solution is therefore known as an electrolyte. Sodium hydroxide is an excellent electrolyte, but there are also many other compounds that you could use.
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2
Obtain a Hoffman voltameter. This glass apparatus is a common piece of laboratory equipment used in electrolysis and is commonly available from suppliers of chemical equipment. A Hoffman voltameter has three vertical tubes that are joined at the bottom with a fourth horizontal tube. The middle tube is completely open at the top, and the two tubes on the side narrow at the top to form airtight connections for rubber hoses. The two tubes on the sides have electrodes at the bottom that exit the tubes through watertight holes. Pour your electrolyte into the central tube of the Hoffman voltameter.
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3
Fill a large beaker partially full with water. Submerge a test tube in the water to completely fill it with water and turn the test tube upside down. Hold the test tube upside down in the beaker with a test tube holder. Repeat this procedure with the other beaker and test tube pair.
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Fill a section of rubber hose with water and connect one end to the gas attachment on a side tube of the Hoffman voltameter. Place the other end of the hose into the beaker. Allow electrolyte to flow through the hose to push any remaining air out of the hose and put the hose into the open end of the test tube. Repeat this procedure with the other side tube of the Hoffman voltameter.
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5
Connect each lead of the battery to one of the electrodes for the Hoffman voltameter. You should observe bubbles forming immediately on the electrodes. The bubbles on the negatively charged electrode are hydrogen gas and the bubbles on the positively charged electrode are oxygen gas. These gas bubbles will flow through the rubber hoses, which will displace the water in the test tubes. Once the hydrogen gas displaces all of the water in the test tube, you can stopper the test tube that's now full of hydrogen gas.
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