How to Produce Hydrogen From Aluminum Cans
Many metals such as aluminum will react with strong bases or strong acids to produce hydrogen gas. Chemists refer to such processes as oxidation-reduction or simply "redox" reactions because they involve both the loss and gain of electrons. A compound that loses electrons becomes "oxidized," and one that gains electrons becomes "reduced." Chemists represent the redox reaction of aluminum from aluminum cans with sodium hydroxide as 2 Al + 2 NaOH + 6 H2O --> 2 NaAl(OH)4 + 3 H2. The aluminum becomes oxidized and the hydrogen becomes reduced.
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Things You'll Need
- Rubber gloves
- 100 percent pure lye pellets
- Small glass container with narrow mouth
- Measuring cup
- Scissors or tin snips
- Empty aluminum can
- Sandpaper
- Balloon
Instructions
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1
Put on gloves and weigh out about 5 g of pure lye pellets on a balance. Transfer the lye pellets to a small glass container with a narrow mouth, such as an empty but thoroughly clean cough-syrup bottle.
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2
Measure 4 oz. of water in a measuring cup and add it to the pellets. Swirl the mixture until the solution turns completely clear with no cloudiness. The glass bottle will become noticeably warm to the touch as the lye dissolves.
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3
Cut about a 2-by-2-inch square of aluminum from an empty aluminum can. Sand both sides of the aluminum thoroughly to remove both the paint on its exterior side and the clear coating on its interior side.
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4
Cut the aluminum square into small 1/4-inch square pieces, then weigh out about 1 g of the pieces on a balance.
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5
Move the bottle containing the lye solution to a well-ventilated area away from any possible ignition source. Add the 1 g of aluminum pieces to the lye solution. Bubbles should be visible on the surfaces of the aluminum almost immediately. This indicates that the solution is evolving hydrogen gas. If you wish to collect or trap the gas, then place the bottle in a large glass bowl and place a balloon over the opening of the bottle and allow the gas to inflate it. Remove the balloon before it overinflates.
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6
Dispose of any leftover lye solution by combining it with 8 oz. of white vinegar to neutralize the lye and then pouring it down a sink or drain.
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Tips & Warnings
You can purchase pure lye online or possibly in a hardware store. Soap makers use it extensively. The substitution with lye-containing products such as drain cleaners is not recommended because they frequently contain other ingredients.
Lye, or sodium hyroxide, is corrosive to tissue. Wear safety goggles and latex gloves whenever working with concentrated lye solutions. The hydrogen gas produced by this reaction is explosive. Keep it well away from any possible source of ignition, including pilot lights on gas appliances.
References
Resources
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