Lab 4 - Gases - 14 Chem 111 Gas Laws 14 Gas Laws Scientists...

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Chem 111, Gas Laws 14 Gas Laws Scientists love to determine relationships between two or more concepts. By knowing a specific relationship, scientists can control their experiments and make predictions concerning future experiments. This helps to limit "chaos" from taking over the lab and saves a lot of time by pointing the scientist in the right direction. Two relationships that we will be trying to figure out is between pressure and volume of a gas at room temperature, and the pressure and volume of a gas at different temperatures. We will use the computer and some sophisticated graphing techniques to unravel this conceptual relationship on a qualitative as well as a quantitative level. Lastly, we will unify these relationships into a nice little package called a physical law.
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15 Chem 111, Gas Laws FOCUS QUESTION Part 1 : What is the Functional Relationship between the Pressure of a Gas and the Volume of a Gas at Room Temperature? A Pre-Lab Checklist Read Tool 14. Summarize or Flow Diagram Procedure Part 1. Make Photocopy of Summary to hand in. Details: 1. This laboratory is coordinated tightly with the lecture. For your laboratory grade, you will follow the procedure, recording all your observations in your notebook. An analysis of your data is not part of your laboratory grade and does not need to be written up in with your notebook. 2. Let us start with a description of the equipment you will use in the lab. The apparatus for this experiment is elegant in its simplicity. There are two burettes containing water that are connected at their bottoms with a hose. The top of one burette is sealed, and contains a volume of trapped air. The pressure on this trapped air can be varied by raising or lowering the relative positions of the two burettes. To see how this works, examine figure 1.
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Chem 111, Gas Laws 16 Water transmits pressure without loss, an observation first made by the French scientist Blaise Pascal in the 1600s. Consider the forces at the liquid/gas interface in burette on the left in Figure 1. Since the water is stationary, the pressure of the trapped gas pushing down on the water must be the same as the pressure the water surface is exerting pushing up. In other words, the forces must be balanced. The pressure the water surface is exerting pushing up comes from the undiminished force of the atmosphere on the burette on the right being transmitted by the water. Thus the pressure of the trapped air on the left must be the same as atmospheric pressure. Now consider Figure 2, where the level of the water in the two columns is not equal. Here the pressure exerted up is equal to the pressure of the atmosphere plus the hydrostatic pressure arising from the difference in height of the water column in the two tubes (see Figure 2), and so the pressure of the trapped air is P = P atm + P hydrostatic (1) where P = trapped gas pressure, P atm = atmospheric pressure, P hydrostatic = hydrostatic pressure Figure .
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Lab 4 - Gases - 14 Chem 111 Gas Laws 14 Gas Laws Scientists...

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