First you need to gather up all of the materials you will need. Below is a list of the following items needed to conduct this project:
• A 9 volt battery
• 2 pencils – remove the eraser and metal part on the ends
• Thin cardboard
• Electrical wire
• Small glass
Are you ready? Let’s get started. Both pencils need to be sharpened on both ends. Cut a piece of the cardboard to fit over the glass and push both pencils through the cardboard so that the pencils are about an inch apart. Dissolve one teaspoon of salt into the water and let sit for a few minutes. Next connect one end of one of the wires to the positive terminal of the battery and the other end to the lead of the pencil. Repeat with the other wire attaching it to the negative terminal of the battery. Place the other ends of the pencils down into the salt water mixture.
What happened? As the electricity from the battery passes through the pencils, the water splits into hydrogen and chlorine gas which appear as very tiny bubbles on each pencil tip. The reason it splits into hydrogen and chlorine rather than hydrogen and oxygen is because salt was added to the water. The chlorine gas comes from the chloride in the salt. The chlorine gas will collect around the pencil tip connected to the positive terminal of the battery (the anode) and the hydrogen gas will collect around the pencil tip that is connected to the negative terminal of the battery (the cathode).