Hydrogen is one of the most efficient, most easily available fuels. The bond energy of the covalent O–H bonds in water is 458.9 kJ/mol. This is a lot of energy that is released in the form of heat when combusted. This is the same fuel that powered the Saturn V rocket that took mankind to the moon several times. It is also a green fuel: the only product is water.

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The makeshift rocket made in this experiment is a bottle filled with 4/9 hydrogen, 2/9 oxygen and 1/3 water. The mixture of the gases is often abbreviated to HHO. A ratio of 2:1 hydrogen: oxygen is enough to achieve maximum efficiency, which is why I have made an electrolysis machine to obtain this mixture of gases in the most accurate manner. The electrolysis machine consists of two electrodes, each made with 3 plates of stainless steel (to increase surface area and hence the production of HHO). A dilute aqueous solution of potassium hydroxide is then added to the container and 36W DC current is supplied. This effectively disassociates the water molecules into its base elements, Hydrogen and Oxygen.

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Electrolysis: 2 H2O → 2 H2 + O2

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The gas obtained is then filled 2/3 of the way in a streamlined, aerodynamic, 2l soda bottle using water displacement. I have observed during the testing periods that soda bottles are much more durable than normal water bottles as they are made of HDPE, which have higher density, rigid plastic- the bottle is pressure rated and can handle the pressure in the rocket for one-time use.

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The now filled, explosive bottle rocket is then fit into the rocket launcher. The water or gas does not escape as there is an airtight seal. At the end of the PVC pipe, there is a spark plug (which is especially chosen so that it does not deteriorate over time). An electronic gas lighter is connected to the spark plug as it is a simple device that can create high voltages to generate a spark. It is relatively portable too.

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When the button on the lighter is pressed, it produces a spark igniting hydrogen fuel in presence of oxygen, forcing the 2 gases to react with each other in an explosive manner to become water vapor. The explosion inside the bottle forces the bottle upward and water is ejected from the mouth of the bottle at high velocities downwards. Following newton’s third law of motion, the rocket launches to about 200 feet high. The force from the rocket is extremely high as observed when a brick used to support the rocket launcher at a 45-degree angle shattered into 5 pieces from the backlash to the PVC pipe.