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Future Car
  Teaching Guide

Activity 2: Grades 5-8
Fuel Cells

Today, we depend mostly on gasoline as a fuel for automobiles. In the future, however, our reliance may shift to a more common fuel substance, hydrogen. As a clean burning fuel, hydrogen may be used in new types of internal combustion engines. Of even greater promise is the use of hydrogen in fuel cells. Fuel cells harness chemical reactions to produce electric current. Without the wasteful generation of heat and unwanted pollutants, fuel cell technology may soon be powering generations of electric cars.




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This activity page will offer:

  • An introduction to the use of hydrogen as an automobile power source
  • A hands-on activity in generating hydrogen through electrolysis

Getting Hydrogen
Whether it is to be used as a clean-burning fuel or as a reactant in fuel cells, sources of hydrogen must be identified. The good news is that hydrogen is all around, especially in water. Every molecule of water contains two atoms of hydrogen. Freed from the water molecule, hydrogen atoms can combine together to form hydrogen gas. In this activity, you'll generate hydrogen gas by splitting water in a process called electrolysis.

Materials

  • Connecting wires with alligator clips at both ends
  • 400 mL beaker (or large jar)
  • Scrap cardboard
  • Two #2 graphite pencils (With graphite exposed at both ends)*
  • One 9-volt battery

    *Teacher note: Prior to the activity, obtain a set of #2 pencils with eraser ends that have been removed. Use a pencil sharpener to expose graphite at both ends of the pencil. Then, dull the pencil points prior to distributing them to students.

Procedure
Basic Prototype

  1. Work in teams of two. Cut out a section of cardboard that is larger than the mouth of the 400-mL beaker.
  2. Carefully punch two side-by-side holes in the center of the cardboard. Make sure the holes are small enough to hold the pencils tightly in place.
  3. Insert two prepared pencils (graphite exposed on either end) into the slots.
  4. Fill the beaker halfway with tap water.
  5. Position the cardboard on top of the beaker. Adjust the heights of the pencils so that the exposed graphite is near the bottom of the beaker.
  6. Use connecting wires to attach the top of each pencil to one of the 9-volt terminals.
  7. Over time, you'll observe the generation of gas bubbles collecting on both of the graphite shafts of the immersed pencils.

Questions

  1. What device supplied the energy needed to split the water molecule into its component atoms?
  2. What are the components of water that are released during its decomposition?
  3. Why did you need to expose graphite on both ends of each pencil?

Inferring
Why didn't gas bubbles collect along the wooden shaft of the pencil?

Make a Model
Consider the process by which water is decomposed into hydrogen and oxygen gas. Then, compare and contrast it with the fuel cell process in which these same gases are combined to produce water. Using toothpicks and gumdrops, construct a representation of this reversible reaction.

Hindenberg
People often connect hydrogen gas with the Hindenburg disaster. The Hindenburg was a German airship that was filled with hydrogen gas. It exploded at its mooring post in Lake Hurst, New Jersey on May 6, 1937. See a Quicktime video and learn more about this disaster at http://www.vidicom-tv.com/tohiburg.htm.

Getting the Lead Out
Although the inner part of a pencil is commonly called "lead," it's not. It's a carbon compound called graphite. Graphite is a soft carbon material that easily breaks apart in molecular sheets. Use Internet and print resources to find out why a pencil's graphite is mistaken for lead. You can learn more about the history of pencils and their components at the URL: http://www.museums.org.za/ sang/exhib/
tri_arch/pencil.htm

Web Connection

How Fuel Cells Work
http://auto.howstuffworks.com/fuel-cell.htm
A great and easy-to-follow introduction to the science of fuel cells.

Fuel Cell Bus Programs Worldwide
http://www.cleanairnet.org/infopool/1411/propertyvalue-19516.html
A site on the global profile and use of fuel cell buses.

Hydrogen, Fuel Cells & Infrastructure Technologies Program
http://www.eere.energy.gov/hydrogenandfuelcells/
Department of Energy site that includes information about hydrogen and fuel cells.

Academic Advisors for this Guide:
Suzanne Panico, Science Teacher Mentor, Cambridge Public Schools, Cambridge, MA
Anne E. Jones, Science Department, Wayland Middle School, Wayland, MA
Gary Pinkall, Middle School Science Teacher, Great Bend Public Schools, Great Bend, KS
Cam Bennet Physics/Math Instructor Dauphin Regional Comprehensive Secondary School Dauphin, MB Canada

 

 

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