• What relationship seems to exist between pressure exerted on the gas and the volume it occupied?

Today, we performed a very messy minilab involving large jars, funnels and hoses, and large amounts of water. The goal was to fill the jar with water using a funnel positioned at three distinct heights, until no more water would enter into the jar under normal atmospheric pressure, and gather data such as the height from the top of the water in the funnel to the floor, the height of the water in the jar, the volume of water in the jar, etc.

First and foremost, we did/are doing this minilab because gas is different than the other two normal phases of matter in a few cool ways. First, we should define “gas”: it is a fluid substance comprised of individual atoms (ex. O2), individual molecules (ex. CO2), or a mixture of both types (ex. air). Unlike solids, gases do not have a definite volume and expand to fill space. Unlike liquids, gases are compressible, meaning that the average distance between atoms in a gas can be reduced, making it pressurized. Unlike both other phases, the Intermolecular forces between gas atoms are weak, so the distances between individual atoms are often great and much larger than the size of the molecules, hence the other two differences.

When we added water to the jars (through a hose that passed through a rubber stopper to keep water and air in the jar), we concluded that the gas must have been compressed by the water because more stuff is being added to the jar; the volume that the gas can take up is decreasing and the gas has nowhere else to go, so it must be compressed.

My picture

My picture. Hopefully you can understand how the lab is set up now

After doing all three tests at the differing heights, we noticed that filling up the jar from a greater height allowed more water into the jar and pressurized the gas inside more than from a lower height. The volume of the gas higher up was, therefore, less than the volume of the gas at the lower height. Furthermore, this leads to the conclusion that the volume of a gas decreases as the pressure exerted on it increases. I think I can also assume this means that volume increases as pressure decreases. Pressure is inversely proportional to volume.

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