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Note:
Once the fan begins to run slower or stops running, complete the following three steps in order to
make the fan run again.
Step 1. Place the exhaust tube (connected to the purging valve) over a container or suitable
receptacle.
Step 2. Open the purging valve by sliding the switch to the right side, purging out the used solution
in the fuel cell chamber and allowing a new volume of ethanol solution to re-enter the fuel cell
chamber, then close the valve (see the picture below).
Step 3. Wait a while and then tap the fan's blade to get it started and watch it go at constant
speed. If the fan still stops running, disconnect the crocodile clips and then exchange them to re-
connect the fuel cell. The fuel cell is able to start the reaction once more (and more hydrogen
protons can permeate through the membrane).
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Experiment 2: Exploring polarity
Step 1. Connect the positive (red) crocodile clip to the positive side of the fuel cell (red "+" mark),
then connect the negative (black) crocodile clip to the negative side of the fuel cell (black "-" mark).
You will notice the fan will turn clockwise.
Step 2. Now repeat the process, this time however connect the positive (red) crocodile clip to the
negative side of the fuel cell (black "-" mark) and connect the negative (black) crocodile clip to the
positive side of the fuel cell (red "+" mark). You will notice the fan will turn counter-clockwise.
Conclusion: the current flows from positive to negative, creating a clockwise spin of the fan. By
inverting the polarity connections, the current flow reverses and makes the fan spin in the opposite
direction.
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