Our project shows how Henry’s Law works. Henry’s Law states that if pressure is exerted on a gas it will dissolve into a liquid. We decided to have our project focus on what will happen if we left a bottle of distilled water, pumped full of air to different pressures, for a week. Our results showed us that the psi that the bottle is pumped to, plays a significant role in the outcome of the experiment. We had four bottles pumped to different pressures 60 psi, 80 psi, 100 psi and 110 psi. We discovered that the bottle pumped to 100 psi created the most bubbles when the bottle was opened and the pressure was reduced. The bottle pumped to 110 psi had bubbles but not nearly as much as the bottle pumped to 100 psi. The bottles that were pumped 60 and 80 psi created no bubbles. The result of the bottles pumped to 60 and 80 psi made sense because there was not as much pressure exerted on the gas to dissolve into the water. On the other hand, the result of the bottle pumped to 110 psi did not make sense because it did not create as many bubbles as the bottle pumped to 100 psi.
Our experiment relates to scuba diving because of the possibility of developing decompression sickness. The water in our soda bottles represents the tissues in a scuba diver. The different pressures we pumped into the bottle represents different diving depths. The time period that we left the bottles sitting represents the time period the scuba diver spent underwater at the certain depth. The fast opening of the soda bottle represents the fast ascent that the scuba diver made. Our results showed that the “scuba divers” that were under the pressure of 60 and 80 psi for seven days did not develop the bends. Of course, we are not meaning that a scuba diver could descend to a depth where the pressure is 60 or 80 psi, for seven days and quickly ascend and not get decompression sickness. In fact, they would not be able to stay under water for seven days and also they would in fact develop the bends if they ascended quickly. The representation of the scuba diver being a bottle of water is not accurate enough to tell if the scuba diver would, in fact, get the bends. The “scuba diver” that was at a depth of 100 or 110 psi for seven days did develop the bends. This shows that a pressure change of 20 psi makes a significant difference on the health of the “scuba diver.” A real diver can develop the bends when they dive to a certain depth, for a long period of time, and then quickly ascend. For example, if a diver stayed at 60 feet for longer than 50 minutes, without a safety stop, he/she would develop the bends. This can be avoided by a safety stop at 15 feet for 3 minutes. This safety stop allows the excess nitrogen in your body to be dissolved. (click here to see more on the bends)
Our experiment had a more than significant amount of error. Our error percentage for the bottle pumped to 110 psi was very interesting (click here to see math on error percentage). The error percentage was high because we counted the number of bubbles, within the area of one square centimeter, in three random spots of the bottle. We only had bubbles that formed around the surface of the bottle pumped to 110 psi. This made us only have bubbles in one of the imaginary squares where we counted for bubbles. Our pictures showed where we counted for bubbles on each bottle (click here to see). The error percentage for the bottle we pumped to 100 psi was 9% error. This error percentage seems reliable based on the number of bubbles created from the bottle. The error percentage for the bottles pumped to 60 and 80 psi was 0% error. This was because no bubbles were created from these bottles, so there was no results to see if there was error.
If we were to do our experiment again we would make a few changes. Our bottle that was pumped to 110 psi was not reliable data. We suspect that there was leak in that bottle, that caused the bottle to produce fewer bubbles than expected. If we were to do this experiment again, we would make at least two bottles for each designated pressure. This would make our error percentage lower and provide us with more valid results. Also, our results would not be effected as greatly, if one of the bottle leaked. For example, out bottle that we pumped to 110 psi.
We suggest that people who try this experiment to make sure they use distilled water and use many bottles for the fixed amount of pressure. The reason distilled water is important because many students have tried this experiment before us, using tap water and received no bubbles. We later learned this was because there were to many impurities in the water. Once again, the use of more bottles for fixed pressures ensures the results to be reliable.
We learned many things from this experiment. First of all, we learned how scuba divers can develop decompression sickness. We learned this through our experiment, when we pumped the bottles to different pressures (depths), letting the bottle sit for a week (bottom time), opening the bottle quickly (making a fast ascent) and watching bubbles form (Decompression Sickness). We also learned how error can play a significant role in an experiment. Our project could have been more reliable if we used more bottles fixed to a certain pressure. Lastly, we learned how to get through an experiment, where one trial (110 psi bottle) failed to provide accurate results.