Generating Hydrogen

Hydrogen is a fascinating chemical element.  In addition to being the most common element in the Universe, hydrogen is found in water and most organic molecules.  Because the light of the Sun is generated by nuclear fusion of hydrogen, it is fair to say that life as we know it depends fundamentally on hydrogen.  Also, recently it has been proposed that our transportation network switch from dependence on distributing hydrocarbons to one in which power is delivered to vehicles by hydrogen. 

Generating hydrogen efficiently is one of the obstacles to this goal.  As a result, it seems a very timely topic for a science fair project. 

There are many methods of generating hydrogen, ranging from electrolysis to thermal decomposition of water.  We will be looking at several techniques which can easily be accomplished in a high school chemistry laboratory, and might be within the grasp of a talented younger student.

Electrolysis is probably the safest technique for generating hydrogen.  You will need a 9 volt battery, two regular No. 2 pencils, a small glass of warm water, a piece of cardboard, salt, and some electrical wire. 

1.  Take the metal eraser end off the pencils, and sharpen them at both ends.

2.  Dissolve about a teaspoon of salt in the water.

3.  Place the cardboard over the glass, and push the pencils thru, about an inch apart.

4.  Connect the pencil leads to the positive and negative terminals of the battery using two lengths of electrical wire.

5.  Immerse the other ends of the pencils into the water.

Gas bubbles will begin to form around the submerged pencil tips, hydrogen on the pencil connected to the negative battery pole, and chlorine on the other pencil.  It is possible to collect the hydrogen in a small inverted beaker placed over the negative pencil, which can then be burned to prove the process worked.

Another way of making hydrogen is quite simple, but uses somewhat more hazardous materials – goggles and gloves are called for here.  The process is simply to immerse a nail in slightly diluted hydrochloric acid.  Bubbles will rise from the surface of the nail, which are filled with hydrogen.  The hydrogen can again be collected in a beaker and burned.

Yet another is to put a small piece of sodium metal into water.  The result is hydrogen, sodium hydroxide, and a lot of heat.  It is again very important to use protective goggles and gloves.  Collecting the hydrogen gas is again straightforward.

Similarly, magnesium metal placed in water will very slowly give off hydrogen gas.  The process can be speeded up by heating the water.  Burning magnesium will continue to burn when immersed in water, pulling the oxygen for combustion out of the water and producing hydrogen gas.  The heat, however, will result in the hydrogen gas burning when it reaches the atmosphere unless the magnesium is deeply submerged, giving the hydrogen a chance to cool off.

Generating hydrogen gas can make a fascinating and attention-grabbing science fair project.  Have fun, take appropriate precautions, and pay attention to detail and you will not only have a winning science fair project, but will also learn a great deal.