Debrief



At first I had estimated that three eggs would do for my egg experiment but I had over looked the fact that errors would occur and three eggs would not be enough. So I came to the conclusion that I needed more eggs, I was able to blow one extra egg for the day of my demonstration due to the lack of time and need for breakfast. I prepared all of my materials which included my mossy zinc, flask, stopper, matches, bottle top and etc. for the taping. I had made minor tweeks to the actual amount of zinc since I had an excess of hydrogen gas from my previous practice rounds. So I used fewer than 20 g of mossy zinc in order to use a sufficient amount without any excess. I also used matches instead of a lighter, which seems to be an insignificant change but it really affected the timing. When the hydrogen gas inserts the egg shell ,as I push the thin plastic tube through the larger hole at the bottom of the shell, there is little time to light a match before the gas escapes through the top hole.

My demonstration was more successful than I had imagined though it was a while before I was able to begin. I knew that I could not use the liquid glue that I had tried to close the top hole during the filling of hydrogen gas. It was not enough to stop the gas from escaping, so I definitely needed to follow the instructions and use the electricians tape mentioned in the materials. Finding the tape was near to impossible and a classmate of mine had to run to one of his workshop classes to get the tape. In the meantime I had positioned the materials for easy accesibility since I knew the taping would have to be flawless and smooth. I looked at the top half of the pop bottle, which served as support for the shell and noticed that there was liquid glue residue at the mouth, at first I wanted to scrape it off so that it would not prevent the shell from effectively cracking. In the end, the glue at the top kept the egg in a stable position. When I received the electricians tape, it was time to do the demonstration. I had wondered how I could get a more explosive reaction, but I had remembered that I had to take 1-2 minutes to feed the hydrogen gas into the shell, which I had previously ignored. This was the factor that would change the effectiveness of the experiment. I took some time when feeding the hydrogen in the shell to see if it would work. In fact it did, the moment I took off the electricians tape and lighted my match, it only took about 3 seconds for the reaction to occur and for the shell to fly across the chemistry room.

The sound, I believe had more impact than the actual splitting of the shell. It was as if someone walked into the room with a balloon and pushed a pencil at its surface. It did not occur in layers, it only lasted for a second. I had not practiced with a high impact explosion such as the one in the demonstration so I had not made a shield for the audience. No one had gotten hurt from shell in their eyes, but it also had to do with the fact that they had sat fairly far away. Also I believe that the drama or interest lies in this danger, so it is very hard to say if I would of made a shield reflecting on it now. The sound was the result of the high concentration of hydrogen gas in that small amount of space. So the more hydrogen fed into the shell, the more the explosion is effective. I learned the importance of instructions through this experience. One final thing that I want to remark would be on how the explosions differed. The last one was definitely a surprise. The class had wanted to see the experiment again so I had prepared the last egg using the same materials. Once I had lighted the match and held it at the top of the shell, for some reason it had not exploded. After everyone sighed, I began to clear off my work space, then the egg spontaneously exploded. The match had long been blown and was no where near the egg. The reaction just continued and the hydrogen was able to mix with the air.