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This illustrates the chemical equation of the electrolysis of water, a form of water splitting

Making water split

As we know, water is actually made of hydrogen and oxygen molecules tightly bound together to form that liquidy goodness we so love to spray on each other. So if it’s made of oxygen, why can’t we breathe it? Actually, we could breathe it IF we could separate the oxygen out from the hydrogen. Fact is, we can’t. If we tried to breathe water we’d instead get the liquidy stuff which of course, our lungs cannot absorb.  If you tend to forget this when swimming, here’s a simple poem to help you remember: The fact is, we cannot lie, if you breathe water, you will die.

Still, they use their gills to separate the oxygen from the hydrogen. For fish, this really is a lot of work. Luckily fish are cold blooded animals and as such do not require as much oxygen as we do.

Alas, we are people though and as such, are much smarter than fish. We can separate the oxygen from the hydrogen using nothing more than a pencil, wire, and a battery.

  1. Fill a glass ¾ full of a water and salt solution. Don’t use very much salt.
  2. Cut a piece of cardboard and place over the top of the glass
  3. Take two pencils and sharpen both ends (if Dad does the sharpening, let him know that it’s easier to sharpen the eraser end if the eraser is removed first).
  4. Poke the pencils through the cardboard so that they extend down into the water solution. Keep the holes fairly close together – make the holes no more than 1 inch apart.
  5. Attach a wire to the positive terminal of a 9 Volt battery and to the lead of one of the pencils.
  6. Attach another wire to the negative end of the 9 Volt battery. Now touch the other end of the wire to the lead of the other pencil. If Dad asks what’s gong on, tell him your figuring out how to make a nice, relaxing bubble bath for him (notice how he watches you from the corner of his eye as he backs away).
  7. Watch the ends of the pencils that are extended into the water. See the bubbles?

The current is passing through the pencil lead and into the water and breaking apart the water molecules into their hydrogen and oxygen components (actually the salt causes a secondary action and causes the release of chlorine instead of oxygen but we’ll not get too technical here). The bubbles forming around one of the pencils is hydrogen and around the other pencil is oxygen (ok, ok, chlorine). And yes, chlorine in larger quantities can be dangerous – if you use too much salt and the solution begins turning green, get the heck out of there quick!

This process is called electrolysis. It’s used in industries too (such as when aluminum is produced) but uses different solutions and much higher currents.

Pot of Gold Mini


Parent/Teacher/Advanced Notes

Although we cannot breathe water, “liquid breathing” is possible. Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid (usually a perfluorocarbon), rather than breathing air. It is used for medical treatment and was once considered for use in deep diving and space travel. It is currently done in experimental cases only.

Experiment Supplies

Supplies: Pencil, Glass jar, Wire (bare)


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