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How to Get Pure Hydrogen From Water

Everything we see around us is a mixture of two or more elements that have combined together to make a new substance. Water, for example, is made up of two hydrogen atoms and one oxygen atom. It is possible to separate hydrogen from water using a scientific process called electrolysis. This very basic experiment is a good way to show children how different things work together to create something completely different.

Things You'll Need

A glass
Water
Salt
2 Number 2 pencils
Pencil sharpener
Cardboard
Test tube
2 electrical wires
Wire clips
9-volt battery

Instructions

- 1
  Remove the erasers and metal sleeves from both pencils, and sharpen both ends of each pencil.
- 2
  Push the pencils through the cardboard. The cardboard should be quite thin and must be larger than the top of the glass.
- 3
  Attach wire clips to the one end of the wires and the battery connectors to the other end.
- 4
  Fill the glass with water and dissolve a teaspoon of salt in the water.
- 5
  Submerge the ends of both pencils in the water so that the sharpened ends of the pencils are in the water and in the air above the glass.
- 6
  Put a test tube filled with water over one of the pencils inside the glass.
- 7
  Attach the wire clips to the tops of the exposed pencils and the battery connectors to the battery. Connect the negative battery terminal to the pencil with the test tube over it.
- 8
  Observe the bubbles that form around the submerged ends of the pencils after about a minute of electrolysis. The pencil connected to the negative terminal of the battery collects hydrogen bubbles, while the positive terminal collects chlorine.
- 9
  Wait for the gas level in the test tube to reach the water level and disconnect the battery. The test tube is now filled with hydrogen.

Insects & Science