In a Parents’ Weekend mini-class for AP Chemistry, we actually did rocket science. Dr. Joanna Smith first explained a basic equation that used hydrochloric acid as a fuel. As Dr. Smith explained, “One of the goals of the lab was to determine the optimum ratio of hydrogen gas to oxygen gas for their combustion reaction that would allow the bulb to be launched across the room the farthest. Hydrogen gas is combustible (fuel) and oxygen gas must be present to for the gas (fuel) to burn.” She told us the hydrochloric acid would react with zinc, which would allow us to siphon off the extra hydrogen gas. A group of mostly puzzled parents nodded heads and guessed at what might seem logical while the theory was explained and diagrammed on the board, but when we got to actually do it ourselves, it was exciting and not too hard. When we mixed the hydrogen gas with oxygen inside a small oval capsule, it formed a simple fuel. Ignited with a click from a switch, the ampules flew into the hallway. Instantly there was a competition to see whose would go farther, and it was easy to see how students get hooked into the world of science. The diagrams on the board made more sense when they described something we had seen happen. I wondered how these reactions were discovered and harnessed, and left wondering what other chemical reactions were firing beyond my perception all day. I doubt many of the parents who entered the Chem lab on Saturday morning considered themselves rocket scientists, but we can now make that claim, and more importantly, see that our students really could go down that path. Extending the boundaries of what feels possible: this is the best of science education.
Here are Dr. Smith’s notes on the chemical reactions behind the experiment:“Hydrogen gas generator: hydrochloric acid reacts with zinc to generate hydrogen gas and zinc chloride (Zn +2HCl -> H2 (g) + ZnCl2) Oxygen gas generator: hydrogen peroxide is decomposed with a catalyst (yeast) to generate oxygen gas and water (2H2O2 -> O2 (g) + 2H2O)
Finally the Hydrogen gas is mixed with the oxygen gas in various proportions to test the distance the micro mole rocket (bulb) is launched. With a spark inside the rocket to initiate the reaction, the hydrogen gas and oxygen gas combine rapidly to produce water and energy. This reaction is exothermic: 2H2(g) + O2 (g) -> 2H2O (l) + energy.”