On Tuesday, we had a short lesson on the periodic table and how chemical reactions work which helped show how they will function in our rockets. We learned how the periodic table is significantly helpful to be tell whether or not an element will react with another. To tell this we can simply look at the column it's in (the main group number) and we can see how many electrons are in its outmost shell. Having previously learned that atoms strive to have complete shells (8 being a full shell) and that they will either give or take away electrons to achieve this, we could easily conclude how reactive a certain element will be with another. For example, hydrogen contains 1 electron in its last energy shell, while oxygen has 6. They both want to have full shells, so two hydrogen atoms will gladly give their electrons to oxygen, bonding with it and creating H2O; better known as water. This is how chemical reactions happen (or rxns for short). When two different compounds are present and the elements when separated are likely to reconnect in different ways, then we add energy to separate them so they can rebind. When they separate and reconnect, energy is released in the form of heat and explosions. Today's experiment was to see how this happens in a rockets parachute-deployment sequence. For the actual experiment we heated a mixture of roughly 65% potassium nitrate with about 35% sorbitol to create our fuel. After carefully stirring and heating it up for awhile, we then poured the now liquid mixture into a small piece of pvc pipe that had been sealed on one side. We did not fill it completely with just the fuel though. We then poured some cement to fill up the rest of the pipe and waited for it to dry. Two days later, once the cement was completely dry, we added a cap on the end with fuel which held the ejection charge. The last step in preparation was drilling a hole in the bottom in which the pressure can escape. After that we went outside and lit the fuse to see if the ejection charge was properly deployed, even though ours ended up failing. (but it was a really cool smoke cloud!) Now, none of this happened by magic. What happened at a molecular level was actually much more intricate! When we heated the two substances I can only guess that this separated the bonds that they already held and turned them into a single homogeneous mixture. This mixture in particular must have been highly flammable, so when lit the energy added must've separated them into smaller gas molecules (from research I believe the reaction is 19 C6H14O6→13 C6H14 + 36 CO2 + 42 H2O) creating an exothermic reaction. The pressure is built up in the small space of the pvc and when it escapes through the small opening that was drilled, which would propel the rocket. The fuse of the ejection charge (which is still inside the tube) is also lit along with the fuel and should've activated the actual charge, ejecting the parachute. Our experiment did not give the results that we had imagined and I'm still unsure as to what exactly went wrong. Maybe we didn't add enough fuel or something along those lines. It was our first rocket experiment so I have no idea exactly what was supposed to happen, but the pressurized hiss of the gas escaping didn't seem to go on for long or nearly at all. Although it did create a nice smoke cloud as the fuel burned. Honestly in our group I did not do much for this experiment except help get supplies. Most of the work was done by Andrew, so we were left to just stir the substances together and heat them up. Even then only one person in our group did that so the rest of us were left to just take watch and record. I wish I could've done more during the experimentation. I worked with Micah, Joseph, and Isaiah in this experiment and we work very well together. Even though we are a capable team, we have a tendency to get distracted very easily, so in future experiments I would like to avoid working all together and rather in smaller groups with each separately. With this experiment it showed me how cool and interesting the rocket projects can be. In the future I would like to continue with this experiment. And of course this can still be continued with building the actual rockets for the motors to launch. Some different things that I can take away from this, was that it's important to do as much work as you can when it's available so that you're not left with very short reflections later on about what you did how it contributed to the lab. But more importantly I learned about how chemical rxns happen and work which is vital in later experiments and work in chemistry. |
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AuthorHello there! I am a sophomore here at High Tech High, and on this blog I will be making weekly posts to what I've been doing in my 10th grade chemistry class! So check back often! Archives
May 2015
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