This is what I hope will be just the first in a series of article directed towards my younger readers, those with a keen interest in science and the world around them. The idea for this article came to me over the weekend when my fourteen year old grandson called and asked me for help choosing a project for his schoolÃƒÂ‚Ã‚Â’s science fair. I had just finished an article on fuel cells as alternative power sources for cars and homes, so the first thing that popped into my mind was to suggest that he build a simple hydrogen fuel cell and put together a Power Point Presentation to explain how it operated. He liked the idea and I hope that you do too.
In this article I will explain how to build a simple, safe hydrogen fuel cell and I will give you a simple explanation of how these cells work. As I explained to my grandson, my explanation is simply a starting point for him/you to base his/your research on while using the cell we will build as a research tool. This project and the ones to follow will also make good father/son, mother/son, father/daughter or mother/daughter learning experiences. We will also begin building our home science lab with this project.
The materials, equipment and supplies that you will need include
1. A 12ÃƒÂ‚Ã‚Â” length of Platinum coated Nickel wire (see Sources)
2. A 3ÃƒÂ‚Ã‚Â” 6d nail
3. A large glass or Mason jar
4. Clear plastic tape
5. Tap water
6. Popsicle stick or similar size piece of wood or plastic
7. A 9-V battery (See Sources)
8. A 9-V battery clip with long leads (see sources)
9. A Digital Multimeter (see Sources)
10. Wire cutters/6ÃƒÂ‚Ã‚Â” diagonal pliers (see Sources)
11. Wire strippers (see Sources)
The laboratory bench
For now any sturdy table or desk will do. I will show you how to build your own lab bench in another ÃƒÂ‚Ã‚Â“The Young ScientistÃƒÂ‚Ã‚Â” article.
Building the hydrogen fuel cell
1. Begin by cutting the Platinum coated Nickel wire into two 6ÃƒÂ‚Ã‚Â” lengths
2. Using the nail as a winding guide, wind each of the 6ÃƒÂ‚Ã‚Â” lengths of wire into coils to form the fuel cellÃƒÂ‚Ã‚Â’s anode (Positive electrode) and cathode (negative electrode), leaving 1ÃƒÂ‚Ã‚Â” of wire free on each coiled electrode.
3. Cut the red (positive) and Black (negative) leads on the battery clip in half. And strip their insulation back 1ÃƒÂ‚Ã‚Â”.
4. Make a 3-way splice between the two halves of the red leads and one of the wire electrodes. Repeat this step with the two black leads and the other coiled wire electrode.
5. Tape the two electrodes to the Popsicle stick using the clear plastic tape.
6. Fill the jar with tap water and insert the electrodes in the water, securing the Popsicle stick to the jar rim with more clear plastic tape.
Now is a good time to take a break and read the instruction manual that came with your new Digital Multimeter if you havenÃƒÂ‚Ã‚Â’t already read it from cover to cover.
Setting up for the experiment
1. Connect the red and black test leads to the free ends of the red and black leads coming from the fuel cell electrodes.
2. Referring to page 12 of the ownerÃƒÂ‚Ã‚Â’s manual set up your meter to read DC (Direct Current) voltage using the Auto-Ranging feature.
Preparing the fuel cell
1. Hydrogen fuel cells work by combing two gases Hydrogen (H) and Oxygen (O) using a catalyst to generate electricity and water (H2O). We will charge our fuel cell with the required Hydrogen and Oxygen gases by first using it as a Hoffman Apparatus to electrically separate water (H2O) into its component gases, Oxygen and Hydrogen, through the process of Electrolysis. To do this, touch the battery clip to the battery for a second or two. You will see bubbles form quickly around and cling to the Platinum coated Nickel wire electrodes. The gas being released at the positive (+) electrode or ÃƒÂ‚Ã‚Â“AnodeÃƒÂ‚Ã‚Â” is Oxygen. The gas being released at the negative (-) electrode or ÃƒÂ‚Ã‚Â“CathodeÃƒÂ‚Ã‚Â” is Hydrogen.
2. During this part of the experiment your meter should read a nominal 9 Volts DC. Once the electrodes are covered in bubbles, disconnect the battery.
3. Fuel cells operate by reversing the electrolysis process during which Hydrogen and Oxygen combine to generate electricity with water and heat as byproducts. The reading on our meter during this phase of the experiment will initially be a little over 2 Volts. As time passes and the gases recombine the voltage gradually drops to 0 Volts.
What are the chemical reactions involved
During the electrolysis phase of this experiment, the battery forces free electrons from the negative electrode into the water. Four of those free electrons combine with four water molecules. Each of those water molecules give up a Hydrogen atom to form two molecules of H2, leaving four negative ions (OH-) which migrate away from the negative electrode toward the positive electrode. The released Hydrogen atoms (gas) bubbles to the surface. At the positive electrode, the battery pulls electrons from the water molecules, splitting them into positively changed Hydrogen atoms and releasing free Oxygen. The Oxygen bubbles to the surface as the positively charged Hydrogen atoms migrate toward the negative electrode.
When the battery is removed and the cell begins functioning as a fuel cell, the process is reversed. The bubbles of free hydrogen molecules clinging to the negative electrode begin to break up into positive charged Hydrogen ions (H+, or Protons) and free electrons. This chemical reaction is speeded up by the Platinum which acts as a catalyst. A catalyst enables a chemical reaction without becoming a part of the chemical reaction. At the positive electrode the Oxygen molecules clinging to the platinum draw electrons from the element. These electrons then combine with the Hydrogen ions in the water to form more water. The oxygen electrode has lost two electrons to each oxygen molecule. The hydrogen electrode has gained two electrons from each hydrogen molecule. The electrons at the hydrogen electrode are attracted to the positively charged oxygen electrode.
Is the Platinum catalyst necessary for the fuel cell to operate? Try replacing the Platinum coated Nickel wire with other metals like Copper, Iron, Aluminum, etc. Record the results in a notebook. Every scientist keeps careful records of all their experiments. What do you deduce from the results?
1. Platinum coated Nickel Wire (Science Toys Catalog)
2. Digital Multimeter and hand tools (Radio Shack)