Tobi Fadiran's List: Fuel Cell Techology

• One way to tell is that there is clearly more gas coming off it than off the one on the right. Hydrogen gas is H2 and oxygen is O2. Water is H2O. It's got two atoms of hydrogen for every atom of oxygen, so it stands to reason that you'll get twice as much hydrogen gas.
• Putting a tablespoon of salt in the water greatly increases the conductivity, and hence the rate at which gas is formed. Connecting two or more 9V batteries in series also speeds up the process. (You can connect any number of them back-to-back: They just snap together facing each other. Use a separate connector at each end of the chain, or cut one connector in half to separate the two terminals. You can build up to some pretty high voltages with just a handful of batteries, so be careful. In fact, with your hands wet with salt water even a single 9V battery can give you a surprisingly nasty shock. With several in series you should wear rubber gloves, in my opinion.)
• Notice how I'm not telling you whether it's the + or - electrode that makes hydrogen. If you know a little chemistry you can easily figure it out, but I urge you not to. Do the experiment first, determine it by the flame test. Pretend you don't know which is the positive ion: The first people who did this didn't know either.
  
• Once you've got a setup that is making a good quantity of bubbles reliably, you can start collecting the gasses by inverting a bottle or test tube of some sort over one of the electrodes (hint: it's more fun to collect the hydrogen). Start with the bottle completely full of water so your gas won't be mixed with air that was already in the bottle (this is an important safety point as we'll see below).

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• Materials and Equipment

   
  • Science fair fuel cell kit; available at www.fuelcellstore.com, SKU: 7235009 
  • Distilled water 
  • Fresh AA batteries (3) 
  • Resistor (1) less than 0.5 ohms. You can purchase this at http://www.mouser.com ,   part number 660-CF1/4CT52RR30J. If you can't find a resistor this low you can use 4 or 5 1-ohm resistors in its place. 
  • Digital multimeter, there are several models available at RadioShack for different prices, such as RadioShack part #22-813, www.radioshack.com/home/index.jsp. Always select a multimeter that fits the requirements of what you are testing. For this science fair project, you will need a multimeter that can test currents from 0–300 mA and can test voltages from 0–10 V. 
  • Alligator clip cables (3), preferably red and black; RadioShack part #278-1157,  www.radioshack.com/home/index.jsp  
  • Helper 
  • Timer 
  • Safety goggles 
  • Lab notebook