[eswenson]

My son is trying to do a science experiment involving solar panels, electrolysis, and a hydrogen fuel cell. Basically, he is trying to generate hydrogen during electrolysis by applying solar power to electrodes in a water/electrolyte solution and then disconnect the power source after some hydrogen has been produced and then measure the electrical output of the "fuel cell" as the hydrogen recombines with the water. The variable in the experiment will be the electrolyte used. What relatively safe and easy to come by electrolytes should he choose from? Where would he go about getting those electrolytes? (One not-so-safe electrolyte he's read about is Surfuric Acid, and he may try to get a dilute solution of H2SO4 as one electrolyte). But what other electrolytes should he try to get? (He's thought about the following: KOH, NaOH, NaCl, Epson Salt, Baking Soda, HCl, Citric Acid, Drain Cleaner (H2SO4?), Vinegar).

In case it is important, he's using one electrode made of platinum-covered nickel wire (for the hydrogen production) and a copper electrode (for whatever other byproduct). The theory is that the hydrogen produced at the platinum electrode will be sufficient, and when the power source is removed, will recombine with the water and produce some current.

Any help would be appreciated as neither he nor I has any real chemistry experience. Thanks.

[Borek]

IMHO electrolytes you listed will do. Some of the will probably prove unusable, but that's OK - that's what the experiment is about.

Note that strong bases are also not too safe. But that's relative thing - strong bases and strong acids are dangerous when concentrated, but not more dangerous than the sharp knife - if handled with care they won't do any harm. When diluted (say down to 1M) they are much safer. Not completely safe, but you have to be really talented to do some harm to yourself using them

[cliverlong]

It seems to me you have two aspects to this that you have highlighted

• The production of hydrogen by electrolysis
• the use of hydrogen in the fuel cell

For the electrolysis in the lab, dilute (10% ?) sulphuric (sulfuric) acid is fine to produce small quantities of hydrogen and oxygen. Sulphuric acid should be easily available from the chemist (drugstore? pharmacy?) Remember, hydrogen is highly flammable and oxygen is the sustainer of fire. Experiment in a well ventilated, non-flammable area.

I'm not clear about why you think different electrode materials are significant

It is not clear to me from your description how, when the source of electric current is removed and electrolysis stops, how the fuel cell process to generate electricity will work. I don't think the electrolysis cell will generate any electric current.

Look here for a discussion of hydrogen fuel cells and their construction

http://en.wikipedia.org/wiki/Hydrogen_fuel_cell



Clive