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Splitting water into Hydrogen and Oxygen

Liquid water can be split into Hydrogen and Oxygen through the process of electrolysis. Electrolysis is the chemical decomposition produced by passing a Direct current through a liquid or a solution containing ions. The liquid or solution containing ions is called electrolyte. There are two electrodes, Cathode (Negative) and Anode (Positive), which are the conductors used to pass electricity into the electrolyte.

The electrolysis of water can be done by using everyday household items.

Things needed:
  • 2 HB pencils
  • 250 mL glass or plastic beaker
  • Cardboard to cover the beaker
  • 9 volt battery
  • 2 wire with alligator clips
  • Water
  • Baking soda
  1. Take 200 ml of tap water in a 250 ml beaker and dissolve some baking soda (Sodium Bicarbonate) in it.
  2. Take 2 HB pencils about the same size and sharpen it both sides.
  3. Now, take a cardboard to cover the top of the beaker. Put two holes in the cardboard with the help of pencils around the center and stick the pencils into it and into the beaker.
  4. Now, using connecting wires with alligator clips connect the exposed graphite of the pencils to a 9 Volt battery.

When you connect the exposed graphite of the pencil to the battery, you notice that gases are coming out of both positive (Anode) and negative (Cathode) terminal. The gas which evolves at the anode is Hydrogen and the gas that evolves at the cathode is oxygen. The gases evolved can be collected using downward displacement of water, that is, by using a test tube or similar container over the gas.


Energy is needed to break bonds between atoms which doesn’t break spontaneously. Here, the energy needed to break the Hydrogen and Oxygen bond is given by the battery.

Try this:

Instead of electrolysis of sodium bicarbonate, try electrolysis of sodium chloride solution or copper sulfate solution.