quick and simple electrolysis demonstration

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My husband has been doing some science demonstrations with the kids recently. Here’s a picture from one of them. He used a 9 volt battery to separate water into hydrogen and oxygen. All that was required was adding a bit of magnesium sulfate (Epson salt) to the water and then dropping the battery in. He positioned two test tubes above the electrodes to collect the separated elements. Can you guess from the picture (and the formula of water) which test tube holds which?Seperating oxygen and hydrogen from water with a 9 volt battery.

He held a small candle to the hydrogen tube to hear it pop, and tried to use the oxygen tube to re-ignite an extinguished candle. Then he put the battery back in with a single jar on top to collect the mix of both hydrogen and oxygen. When a significant amount had accumulated he used a lit match to create an impressive burst of fire.


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9 thoughts on “quick and simple electrolysis demonstration

    • With hydrogen and oxygen separate there is little to see. The hydrogen makes a popping noise when a match brought to it, but that was it. With both the hydrogen and oxygen in the same container, it made an impressive but very, very quick fire. I’m not nearly skilled enough to catch the moment of action. It looks impressive. It is fun to do. It is just really quick and hard to photograph.

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  2. Electrolysis is such a brilliant scientific demonstration, isn’t it? Two GASES from this wet stuff – really?! We did electrolysis recently, too. We got very excited when we tested for hydrogen and heard it pop. After that we were slightly disappointed when we tested for oxygen, so we made oxygen via “elephant toothpaste”, which rekindled our flame in a much more exciting way! We also inadvertently made chlorine when we used salt as an electrolyte, but we got it right in the end. I love your husband’s way of doing it – easy-to-set-up but a perfect demonstration.

  3. My daughter is 7 1/2 and with my supervision we did this experiment to help her earn a Girl Scout Patch. This was fun and exciting. We can’t wait to do it again.

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