Analytic Essay

 

My lab on Boyle's Law was a very good one. It was exactly what I thought it would be and the results turned out to be very close to my hypothesis. My experiment utilized the formula of Boyle's Law. This formula basically says that there is an inverse relationship between pressure and volume. My experimented illustrated this. When I went down to deeper depths where the pressure is greater, the air bubble in my container shrank. This shows the inverse relationship which is the greater the pressure, the smaller the bubble becomes. In other terms, this means that when you descend to greather depths, the air bubble size gets smaller. This statement is the basis of Boyle's Law. The formula for Boyle's Law is P1 x V1 = P2 x V2. P stands for the pressure and V stands for the volume. This means that the pressure of the first depth multiplied by the volume at that depth is equal to the pressure of the second depth multiplied by the volume at the second depth. Here is an example:
1 x 13.5 = 4/3 x Y
multiply each side by 3/4
10.125 cm. = Y
If I plug the value for Y back into the formula:
1 x 13.5 = 4/3 x 10.125
13.5 = 13.5
This formula says that if the size of the air bubble at one atmosphere of pressure is 13.5 cm., it will be 10.125 cm. at 1 1/3 atmospheres of pressure. As the pressure increased from one to 1 1/3 atmospheres, the size of the air bubble decreased.
These results and Boyle's Law are very relevant to scuba diving safety. When I go down to the bottom of the pool, I am under more pressure than I am at the surface. With greater pressure, I need denser air with a higher concentration of oxygen. If I had a hose up to the surface and breathed surface air at 30 feet deep, for example, the air from the surface would be less dense and have a lower concentration of oxygen than I need at my current depth. When you descend, the air in your tank becomes compressed, or denser, and there is a higher concentration of oxygen in a smaller volume. So Boyle's Law tells me that I must breathe compressed air at greater pressure. Because the volume of air decreases at greater depths, this means that I will empty my scuba tank faster at greater depths. I need to be aware of how much air I have and how fast I'm using it, especially at great depths.
Another rule of scuba safety that is covered by Boyle's Law is that you should not hold your breath. I stated earlier that as you descend to greater depths, the volume of air decreases. But what happens to the air volume when I ascend to the surface? The volume of air increases. This implies that if I fill my lungs and hold my breath at a depth of even as little as nine feet, as I ascend, the volume of the air in my lungs increases. By holding my breath, I am forming a closed system with my lungs. As I go back up and the volume of air increases, none of it can escape, and I can pop my lung. If this was an upside down Coke can, that is an open system and air can escape, so the Coke can woouldn't burst. But when I hold my breath, I close the airway and the air can not escape. The air in my lungs increases and my lungs can pop. This does not happen if you fill your lungs at the surface, descend to eleven feet, and then ascend to the surface. When you fill your lungs at the surface, you are at one atmosphere of pressure (1 ATM). When you descend to 11 feet, your are at 1 1/3 ATM. (Every 33 feet represents one ATM. For example, 33 feet is 2 ATMs, 66 feet is 3 ATMs, etc.) Let's say that your lung capacity is two cubic feet. At one ATM, the volume of air is 2 cubic feet. Boyle's Law tells us that at 1 1/3 ATMs, the volume of air in your lungs would be smaller or 1 _ cubic feet. When you ascend to the surface, the volume of air in your lungs would return to two cubic feet. However, if you filled your lungs to their maximum capacity of two cubic feet underwater at 1 1/3 ATMs, when you ascend to the surface, the volume of air in your lungs would be 2 2/3 cubic feet or more than your lungs can handle. They would pop.
Many experiments contain some error. While doing my error analyses, I realized that I did not have that much error in my project. First of all, in my hypothesis, I could be very accurate because Boyle's Law provides a formula for predicting results. However, there was some inaccuracy when conducting the actual experiment. One source of error was in the measurements. It is difficult to measure under water. I tried to measure with a ruler under water and write down the measurements. But it was difficult to measure accurately, and the gloves restricted my movements. As an example of the error, at a depth of 11 feet, the measurement should have been 10.125 centimeters based on Boyle's Law, but my results showed 10.5 cm. As you can see, I was not off by a huge amount. I think that this experiment did not have that much error because it is fairly simple if you are able to maneuver well in the water with scuba gear.
There are not many things I would change about my project, but one thing I would definitely change is my container. My container was a big plastic tube, which was very hard to drag down to the bottom of the pool and to greater depths when we dove off Catalina. Instead, I would have used a slender tube with measurement markings down the side. I would also avoid using the china markers. They work well, however, they are extremely hard to keep track of under 60 feet of water and after five minutes they start to unravel. Also, it was difficult to write down the measurements on the clipboard. It would have been easier to just make a mark on the cylinder, then measure the size of the air bubble using the mark later, at the surface. Overall, I was very pleased with my experiment and would change very little if I had the opportunity to do it again.
I obtained a lot of knowledge by completing this project. Probably the most important thing I learned during the DEEP program is Boyle's Law and how it relates to scuba safety. I was unaware of Boyle's Law before the DEEP program. I also learned that water does not compress at great depths, but air does. That is why you have to constantly clear your ears when you descend. The air in your ears becomes pressurized, so you have to constantly clear them so they do not explode. During my project, I was considering a few things that I might research further. One thing is, what would happen if I brought down carbon dioxide or some other type of gas instead of air in the container? Would the results be the same, or different? I hope I can get to research and experiment with the concept of using other gases instead of air or oxygen.
Overall, I was pleased with my experiment and would make very few changes. I had a great time doing this project and learned a lot about Boyle's Law and how gasses change under pressure.


Background Essay Analytic Essay Method & Materials Hypothesis
Experiment Problem Statement Diagram Conclusion
Enhancements Photos Animation Videos
Links Bibliography St. Matt's DEEP Site Home