Experiments for Kids: Electrolysis

11th November 2014

Science

chemical reactions part

Part 3 in our series of chemical reactions for kids shows another fun experiment that kids can understand and enjoy. Our experiments for kids are presented in a simple way and are safe for young children to carry out, although the supervision of adults is recommended.

Experiment 3: Splitting Water (Electrolysis)

Chemical reactions occur when two or more elements or compounds interact with each other to form new products. In nature, reactions often occur as part of a more complex set of reactions. This includes, for example, how we digest food or produce energy.

Experiment 3 demonstrates the concept of electrolysis. This is a special type of reaction fuelled by electricity. In this case, we’re looking at splitting water into oxygen and hydrogen which can be used to produce energy in industrial applications.

This reaction relies on a battery with two terminals; a positive and a negative – both immersed in water. As electricity is switched on, it can flow between the two terminals.

As pure water is not a very good conductor of electricity, in this case we’re adding baking soda and other ingredients which will work as an electrolyte.

Ingredients:

  • Water (to fill container)
  • 2 screws (to work as electrodes)
  • 9V battery (a 6V battery will also work)
  • Pinch of baking soda
  • Pinch of salt (sodium chloride)
  • A few drops of lemon juice
  • A few drops of dish washing detergent
  • Small container, ideally clear plastic

Method

  1. Prepare your container by placing the two screws at the bottom of the container and screwing them into the container. They should not touch each other.
  2. Connect the terminals to the battery. Ask an adult for help with this stage.
  3. Fill container with water, making sure it remains water-tight (you may need to glue the screws onto the container).
  4. Mix in the baking soda.
  5. Switch on the battery and watch the results.

As you switch on the battery, you should start to see bubbles forming. These are gases including hydrogen, oxygen and carbon dioxide.

Clean the container and repeat again with lemon juice, salt, detergent and just water to see if there are any differences. You may have to try different amounts of the electrolytes (baking soda, lemon juice, salt and washing-up liquid) especially if you have a large container. The trick is to start small and gradually increase until you see some results.

You’ll probably find that salt will give you the best results, while water by itself is a very poor conductor.

Salt works because it’s also a good electrolyte, just as baking soda is. The problem with salt – and the reason your parents may want to give it a miss! – is that it produces chlorine gas (Cl2) which is a hazardous chemical and should not be inhaled.

We hope you’ve enjoyed trying out electrolysis just as much as experiments 1 and 2. Don’t miss the final experiment for kids that will be uploaded within the next few days. Remember, always  wear safety glasses and gloves to carry out chemistry experiments!

See More from ‘Chemical Reactions for Kids’

Experiment 1: Heat and Release of Gas
Experiment 2: Green Pennies and Copper Plated Nails
Experiment 4: What Factors Affect a Reaction?

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