Electrolysis and Hydrogen Fuel Cell Powered Car

Electrolysis and Hydrogen Fuel Cell Powered Car
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Copyright 2009 General Electric Company
Definitions we need to know:
Hydrogen – simplest and lightest element in the periodic table (#1); it exists as a colorless odorless gas
naturally; an atom of hydrogen consists of only one electron and one proton; it is the most abundant
element in the universe but does not exist buy itself in nature only in chemical compounds like water
Electrolysis – the use of electricity to separate water into hydrogen and oxygen
Water – H2O; two atoms of hydrogen and one atom of oxygen; poor conductor
Electrode – electrical conductor
Cathode – negative terminal of electrolytic cell
Anode – positive terminal of electrolytic cell
Electrolytic cell – negatively charged electrons from power source pass through water from cathode to
positively charged anode; in order for current to flow water near the cathode decompose into negatively
charged hydroxide (OH-) and positively charged hydrogen (H+); the hydrogen atom picks up an electron
from the cathode due to the opposite charges and becomes neutral; when two neutral hydrogen atoms
combine a hydrogen gas is formed as is evident by bubbling near cathode; negatively charged hydroxide
ions are attracted to the positively charged anode and gives up its electron to the anode leaving a neutral
OH that can bond to two other neutral OH to form an oxygen gas molecule and two water molecules
electricity + 2 H 2 O →O 2 +2 H 2
H 2 O → H + + OH −
4OH − →O 2 +2 H 2 O + 4e −
Fuel Cell – uses hydrogen and oxygen to create electricity; opposite of our electrolysis experiment
PEM – Proton Exchange Membrane Fuel Cell
How does a PEM work?
Hydrogen is fed into the anode where a catalyst (like the salt in electrolysis) separates the negatively
charged electrons from the positively charged protons. The electrons must travel through an electrical
circuit to reach the other side of the cell because they cannot travel through the membrane., creating a
current. The protons move through the electrolyte to the cathode and combine with oxygen and electrons
to make water and a little heat. The product of fuel cells is water or water vapor because the heat
produces puts it into vapor states.
The amount of power produced by a fuel cell depends on the size of the fuel cell, the fuel cell type, the
temperature of operation, and the pressure of the gases supplied to the cell. A small energy use of a single
fuel cell is the car demo suggested here.
Why are Hydrogen and fuel cells so important?
We consume petroleum based fuels 100,000x faster than they become available. The United States gets
most of its energy from fossil fuels that we import from other countries, more than 50% of US petroleum is
imported. The consumption of these fuels has caused significant damage to the ecosystem and is believed
to be the primary cause of global warming and alterations in weather patterns. This consumption is also
associated with the increase in cases of asthma and lung cancer. Hydrogen is a cleaner and more
sustainable form of energy for our growing population. A fuel cell can convert water into hydrogen and
oxygen producing usable electrical energy like the energy powering this car.
Electolysis Activity
Goal of experiment
Use electrolysis to decompose water into hydrogen and oxygen. Begin to understand the impact of clean
energy and the power produced from combining water and electricity. Understand the fundamentals of
fuel cells.
Items needed for the experiment (per group):
1. Water
2. 6 volt lantern battery
3. Aluminum foil
4. Test leads with alligator clips at both ends
5. Salt
6. Clear plastic cup
Instructions for the experiment:
1. Make two electrodes out of the aluminum foil (should be very close in size)
2. Fill cup ¾ full of water
3. Attach one test lead from the positive terminal of the battery to an electrode and attach the second
test lead to the negative terminal of the battery and the second electrode.
4. Place the electrodes in the water bath without allowing them to touch.
5. Observe
6. Add salt to the water bath
7. Observe
Items needed for fuel cell car demo:
1. DI water
2. Fuel cell car kit - http://www.thamesandkosmos.com/products/fc/fc2.html
Instructions for the demonstration
1. Fill both cells with DI water
2. Use battery the run the PEM and separate the water into hydrogen and oxygen.
3. Connect the PEM to the leads on the car motor and watch the car drive.
Understand the connection between electrolysis and fuel cells
Become more aware of the use of petroleum fuels and reduce the effect we have on our
What other sources of energy could be used to split the water? ie. Solar
Name ___________________________________
Electrolysis Activity Sheet
1. What will happen when we place the electrodes attached to the battery into the water bath?
2. Why is it important not to allow the electrodes to touch each other?
3. What will happen when we add salt to the water bath?
1. What do you see on each electrode? Is it the same on both electrodes?
2. What difference did adding salt make? Why?
3. Which electrode is producing oxygen? And which is producing Hydrogen? How can you tell? What
is the chemical reaction taking place? Use H2O in your answer.
1. How could we trap the gas being produced at the electrodes?
2. What applications would this trapped gas be useful for?
Name ___________________________________
1. Name the three main parts of a fuel cell
2. Describe a PEM
3. How does a fuel cell make electricity.? Draw a picture.
4. How will fuel cell cars differ from the cars we drive today?
5. What are two advantages of fuel cell electricity cars?
Fuel Cell Activity Sheet
This activity is a wonderful combination of chemistry, energy and physics in real –life application for late
elementary levels. It lends itself to some great problem-based learning focusing on alternative energy
sources, “greener” energy sources and possibly less expensive sources. This activity supports the matter
and energy state standards.
NYS Standard 4: The Physical Setting
Key Idea 3: Matter is made up of particles whose properties determine the observable characteristics of
matter and its reactivity.
P.I. - 3.1 Observe and describe properties of materials, using appropriate tools.
P.I. – 3.2 Describe chemical and physical changes, including changes in states of matter.
Key Idea 4: Energy exists in many forms and when these forms change energy is conserved.
P.I. – 4.1 Describe a variety of forms of energy and the changes that occur in objects when they interact
with those forms of energy.
P.I. – 4.2 Observe the way one form of energy can be transferred into another form of energy present in
common situations.
NYS Standard 4: Living Environment
Key Idea 7: Human decisions and activities have had a profound impact on the physical and living
P.I. – 7.1 Identify ways in which humans have changed their environments and the effects of those
NYS Standard 6: Interconnectedness : Common Themes
Key Idea 2: Models are simplified representations of objects, structures or systems, used in analysis,
explanation, or design.
NYS Standard 7: Interdisciplinary Problem Solving
Students will understand the relationships and common themes that connect mathematics, science, and
technology and apply the themes to these and other areas of learning.