Here we see how we can 'split' water into its two parts - oxygen and hydrogen using a process called electrolysis.
Youtube video, suitable whether of not you have the board with you.
See board images.
Tutorial guide for when you have the board with you.
So, what have we here? To start with, three tanks! All of which are constructed the same way. They have two sections and there are holes in the plate that divides them. We need these holes because we have an electrode in each section, one connected to the positive terminal of our supply and one to the negative, so the holes allow more current to flow because they allow a direct route and so gives less resistance.
When we allow electricity to flow between the electrodes then a very strange thing happens, we split the water into its two chemical parts – hydrogen and oxygen. These are the bubbles you see in the tanks. The oxygen comes of the positive electrode which is called an anode, and the hydrogen comes off the negative one which is called the cathode.
So why three tanks? It’s showing us what happens when we add a bit of salt into the water. The lefthand tank is pure water with no salt, the middle tank contains water where we put 10 grams of salt for every litre of water and the righthand tank has 20 grams for every litre. Look at the difference it makes? The amount of gas in the righthand tanks is much greater than the lefthand one. The ammeters show us the current and the righthand tank is much greater.Note that we are getting twice as much hydrogen as oxygen and remember that the chemical name for water is H2O – so two modules of hydrogen and one of oxygen!