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Manual of Experiments:
The mini fuel cell can simply be used to demonstrate that it works, and to show a fuel cell's simplicity and such like things. However, the Mini Fuel Cell has also been designed for other more challenging experiments. Five suggestions are given in the "Manual of Experiments". This manual of experiments is presented in electronic form below.
Teachers and lecturers are permitted and encouraged to copy the instructions presented here and to use them in their own worksheets and or laboratory instructions. You will almost certainly need to modify them somewhat for your own use, this is much easier when they are supplied in this electronic form. For this reason this Manual of Experiments is available exclusively in this electronic form.
With your mini fuel cell you should have received a short manual, which gives instructions for the basic care and operation of the cell, and also explains its chemistry. The experiment instructions below sometimes refer to these instructions.
1. Fuel Cells - Electricity from fuel without burning
A series of short experiments or demonstrations that compare fuel cell operation with the ordinary burning of fuel. The aim is a thorough understanding of what is going on in a fuel cell. Most rely on the fact that the cathode is at the end of a tube, into which can be put (for example) oxygen, carbon dioxide, or water.
2. Investigating the effect of temperature on reaction rate
The current from a fuel cell IS the reaction rate of the fuel! Because the cell is small and compact it can be heated, or put under pressure, and an ammeter connected to it gives a very immediate and quantitative indication of reaction rate.
3. Measuring Oxygen Consumption
One of the best features of the electro-chem-technic cells is that their design allows the consumption of oxygen to be measured. The rate at which oxygen is consumed can be compared with the electric current. The results can be used to:-- Notice that the oxygen consumption is proportional to current, and use this to reinforce an understanding of how fuel cells work.
- Relate the volume of gas consumed to the charge, and using known formulas such as PV=nRT (the universal gas law), verify the chemistry of the cell, i.e. 4 electrons released per oxygen molecule.
- Assume the chemistry of the cell given in the manual is correct, and use the same calculations of charge and gas volume to find the space taken up by one oxygen molecule at NTP.
4. Investigating the rate determining step of a multi-step reaction
The reaction of methanol in the fuel cell involves a multistep reaction. However the intermediate products, methanal (formaldehyde) and methanoic (formic) acid, are quite readily available The cell can be fuelled with these, starting the reaction at different points in the chain. Since the current produced can give the rate of reaction, this allows a quantitative study of an interesting multi-step reaction. Full guidance given.
5. Measuring the power of a cell
A Physics experiment. The fuel cell has quite a high internal resistance, and so lends itself well to maximum power transfer experiments.
