Overview:

Students will be asked to build cars out of K’nex kits using the PEM fuel cell as a power source. Their objective is to make the car go the furthest out of all students.

Materials:

1. For class/group projects:

·  Deionized water

·  3 V battery pack with Connecting wires and gator clips

·  Syringe

·  Beaker

For each student group:

·  PEM Fuel Cell

·  Motor

·  Tubing

·  Clamps

·  K’nex Kit

Background:

In these experiments we will be using a proton exchange membrane (PEM) fuel cell. The fuel cell works by placing deionized water into the tube connected to the hydrogen side of the fuel cell, the fuel cell is labeled accordingly. The fuel cell is then hooked up to a battery, which allows the electrolysis to occur. Electrolysis is the splitting of water. The hydrogen that is produced will push the water out of the tube, and the oxygen that is produced will be released into the atmosphere. Once the hydrogen is trapped the fuel cell will be disconnected from the battery and now connected to the motor of the car. The hydrogen, the fuel, will be split into a proton and an electron. The proton will go through the membrane, while the electron goes through a circuit and meets the proton on the other side of the membrane. The product of this source of electricity is hydrogen.

Vocabulary:

·  Electrolysis

·  Proton Exchange Membrane

·  Deionized Water

·  Fuel Cell

Discussion/Questions:

·  What are some modifications to this model that would need to be made for a car to use in everyday life?

·  Have students draw a car powered by a fuel cell, when the deionized water is split by power from a solar cell. Discuss pros/cons.

·  What are some differences between electric cars and fuel cell cars?

·  List the advantages and disadvantages of using a fuel cell car.

Activities/procedure:

For best results on the electrolysis use the following procedure:

  1. Cut the tubing into two pieces, one length of 16.5 inches and the other 1.5 inches. Different lengths may be used for a different amount of gas.
  2. On the hydrogen side of the fuel cell put one tube over each hole.
  3. Using a syringe fill the long tube with distilled water, so that the water flows to the short tube and fills it as well. Clamp the short tube before releasing the syringe. When finished both tubes should be filled with water.
  4. Clamp the long tube.
  5. Hook up the black knob on the fuel cell to a wire with the corresponding knob (black with negative battery end) on a 2V battery on the other end.
  6. Unclamp the long tube, making sure that the fuel cell is set on its side with the long tube on the bottom. Gravity will help reduce the air bubbles in the tube.
  7. Hook the red knob on the fuel cell to a wire with the corresponding knob on the battery. This will cause the electrolysis to occur, the long tube should begin filling with gas.
  8. As soon as the last drop of water passes the clamp, clamp off the tube.
  9. Disconnect the wires from the battery and place the fuel cell in the pre-built K’nex car.
  10. Hook up the wires as was done with the battery, only this time hook it to the motor. See steps 5 and 7 for better explanation.
  11. Car should run on immediate connection.

Details/Hints:

·  The furthest distance recorded by our students was 150 feet. However in the beginning of the fuel cell use we were only getting 50-60 feet.

·  First time using a fuel cell saturate the PEM for about twenty minutes with the deionized water. Follow steps 1-4 in the activities/procedure section. The distance will increase as continued use over an extended period of time.

·  The fuel cell will be more efficient if the oxygen is stored as well. However, the weight of the oxygen and extra tubing may make it more difficult to move.

·  Air and water do not flow through the membrane. Therefore make sure no water bubbles are present in the tube and that the fuel cell is initially completely full of deionized water.

·  When experimenting with the cars, children noticed that the cars would stop between 30 seconds and 5 minutes, than continue. However, there was no pattern as to when it would occur in the cars travel.

·  Caution when using the battery for electrolysis, use correct hook ups. The fuel cell will blow its diode if put together backwards. If this should occur, the diode may be replaced by unsoldering the diode and soldering on a new diode. However, it is a reversible fuel cell, therefore the wires may be switched when hooked to the motor; this will cause the motor to move the opposite direction.