This short video clip is part of a hands-on science demonstration on fuel cells which I developed a few years ago. Additional modules to follow if there is interest, and as time permits.
Water is made of hydrogen and oxygen. How can you break it into its components? Sawing it sure doesn’t work. Nor does pounding it with a hammer. If you boil it, you get water vapor … but it is still water. Fortunately, there is an easy way to separate water into its components. A few volts of electricity (DC) can do it, via a process known as electrolysis.
At low voltages, however, water behaves like an insulator. To make it work, we must dissolve an ionic substance, such as a salt, acid or base in the water, increasing its conductivity. While strong acids and bases (such as draino) work well and produce lots of bubbles, they can be very hazardous. Instead, we are going to use a weak base, baking soda.
In this experiment, a heaping spoonful of baking soda is dissolved in water. Two metal rods are placed in a jar. The baking soda solution is then poured into the jar, and 4.5 volts DC connected across the electrodes. A steady stream of bubbles can be seen at each electrode. The hydrogen bubbles form at the negative electrode. Oxygen and other gases are produced at the positive electrode.
This science experiment is easily done at home. Watch for an advanced version which is in the works. Caution: Do NOT connect this apparatus to an AC outlet … it doesn’t work, and could be deadly.