Energy and Science Projects
For Students

 Splitting Water

H₂O Hydrolysis

Electricity is "created" when certain chemicals react together. We use chemically- made electricity to power many machines from flashlights to a watch or sometimes a car. Yes, there are cars that run on electricity! The devices that store electricity are called batteries. Electricity can also be used to produce chemical changes.

Water is a simple chemical made from two gases -- hydrogen and oxygen. Every molecule of water has two atoms of hydrogen for every atom of oxygen. H₂O is the chemical formula for a molecule of water.

If an electrical current is passed through water between electrodes (the positive and minus poles of a battery), the water is split into its two parts: oxygen and hydrogen. This process is called electrolysis and is used in industry in many ways, such as making metals like aluminum. If one of the electrodes is a metal, it will become covered or plated with any metal in the solution. This is how objects are silverplated.

Try This!

You can use electricity to split water into its two gases -- oxygen and hydrogen.

What You'll Need

• A 9 volt battery
• Two regular number 2 pencils (remove eraser and metal part on the ends)
• Salt
• Thin cardboard
• Electrical wire
• Small glass
• Water

What to Do

1. Sharpen each pencil at both ends.
2. Cut the cardboard to fit over glass.
3. Push the two pencils into the cardboard, about an inch apart.
4. Dissolve about a teaspoon of salt into the warm water and let sit for a while.
5. Using one piece of the electrical wire, connect one end on the positive side of the battery and the other to the black graphite (the "lead" of the pencil) at the top of the sharpened pencil. Do the same for the negative side connecting it to the second pencil top.
6. Place the other two ends of the pencil into the salted water.

Results

As the electricity from the battery passes through and between the electrodes (the pencils), the water splits into hydrogen and oxygen, which collect as very tiny bubbles around each pencil tip.

This Energy Education Project comes from the California Energy Commission
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