Fuel Cell Car Lab: Qualitative Gas Analysis
Objectives:
1. Students will assemble the fuel cell car kit according to instructions and produce gases in
test tubes.
2. Students will test these gases with the “pop test” and the “glow test” to determine the
nature of the gas.
Background:
A fuel cell is a device that that
can use a constant supply of fuel
and convert it directly to
electricity without the need for
combustion. We will be using a
special type of fuel cell today
called a Proton Exchange
Membrane (PEM) fuel cell. This
type of fuel cell uses hydrogen
gas as the fuel, and is works to
separate the electrons from the
Figure 1
protons. The electrons travel one
way through a circuit and power an electric motor. The protons travel a different way through the
proton exchange membrane and rejoin the electrons on the other side of the fuel cell where they
form water in the presence of oxygen (See Figure 1).
In this exercise, we will use the fuel
cell in reverse to split water into
hydrogen gas and oxygen gas (See
Figure 2). This requires a power
source such as a solar panel or a
battery. In a later experiment we will
use the fuel cell in its more
commonly used manner to use
hydrogen gas as a fuel to power the
electric motor on the car.
Figure 2
You will need the following materials:
• Safety glasses
• Solar panel
• Electric Light (60-100 watt bulb)
• Car body with fuel cell
• Syringe with tubing nozzle
• Distilled water (Use only distilled water for experiments with the fuel cell. The water
must be free of all ions and salts or it can destroy the fuel cell. NEVER USE WATER
FROM THE TAP OR BOTTLED DRINKING WATER.)
• Large plastic tub
•
•
•
Bunsen burner and starter
Wooden splints
Test tube
Setting up:
1. Fill the plastic tub with distilled water
2. Look at the fuel cell. It should have four tubes sticking out of it: Two short tubes with red
stoppers, one on each side at the top, and two long tubes with clear plastic nozels. The
long tubes should not be attached to the hydrogen and oxygen tanks.
a. If your long tubes are still attached to the hydrogen and oxygen tanks, gently
remove one end of the tube from the fuel cell and push the whole piece of tubing
down through the tank (it may be stuck tight, press gently down where the tubing
meets the tank). This will free the tube from the tank. Reattach the end of the
tubing without the clear nozzle to the fuel cell.
3. Place the ends of the long tubing in the tub of distilled water.
4. Prepare the fuel cell as follows:
a. Remove the red stopper on one side of the short tubing.
b. Fill the syringe half-full with water.
c. Insert the syringe nozzle into the short tubing.
d. Gently push on the end of the syringe to push water
through the fuel cell.
e. When no more bubbles are seen exiting the fuel cell,
remove the syringe and recap the short tubing on the fuel
cell with the red stopper.
f. Discard water from the syringe back into the tub.
g. Repeat the procedure for the other side of the fuel cell.
5. Plug in the solar panel to the metal
terminal strip as indicated in the figure
at right.
6. Plug in the fuel cell into the metal
terminal strip as indicated in the figure
at right. Pay close attention to the
colors of the wires.
7. Turn on the light and position it about
10 cm from the solar panel so that the
light is shining directly onto the panel.
8. You should now be observing bubbles
coming from the ends of the long tubes that are under the water in the tub.
Collecting Gases and Performing
the “Pop test” and the “Glow test”
1. Start with the long tubing
coming out of the blue-colored
side of the fuel cell. Remove
the other long tubing from the
water for the time being.
2. Fill the test tube with distilled
water and position the tubing so that bubbles flow into the water filled test tube. The test
tube should be held with the opening pointing down so that the gas will rise to the top and
be collected. What do you notice about the water level of the test tube?
3. Once the tube is 1/3 filled with gas, carefully remove it from the water while always
holding the opening pointed down so that the gas does not escape (see figure above). Pass
the tube over a flame. Do you hear a “pop”? Record your observations in the data table.
4. Refill the test tube with the gas from the blue side as above. Carefully remove the test
tube from the water and carefully insert a
glowing wood splint (see below). What do you
notice? Be very careful with the glowing splint
as it may flame up again. Record your result in
the data table.
a. How to prepare a glowing wood splint:
Light the end of a wood splint with a
flame. Quickly blow out the flame so
that only a glowing ember remains. If
you do not see a red glowing ember,
reflame the tip of the splint as above. Be
very careful with the glowing wood
splint as it may flame up at any moment.
5. When you have finished both the “pop test” and the “glow test” with the gas from the
blue side, remove the long tubing from the blue side and put the long tubing from the red
side of the fuel cell into the water. Fill the test tube with gas from the red side and repeat
the two tests. Record your data in the data table.
Data Table:
Gas from:
Blue side
Pop test result
Glow test result
Name of gas
Red side
Data analysis:
Now that we know the results of the “pop test” and the “glow test”, we can try to figure out
which gas (hydrogen or oxygen) is coming from which side. Hydrogen is a highly reactive and
explosive gas. It is likely to result in a “pop” when in contact with a flame. Oxygen is necessary
for combustion and if more oxygen is present, a fire will glow more brightly. Based on this
information, write which gas you think is coming from each side of the fuel cell.
Questions:
1. Write a balanced chemical reaction for the splitting of water
2. In the “pop test”, oxygen from the air combines with hydrogen and the energy released
causes a “pop”. Write a balanced chemical reaction for this process.