Lab Summary 9 PDF

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Experiment 9 - Behavior of Gases: Molar Mass of a Vapor Purpose: We will analyze change in temperature and pressure and how this affects volume of a fixed amount of gas. When we determine the molar mass of a gas, we will be doing so from knowing its mass, temperature, pressure, and volume. Part A We will use the report sheet to record the data collected by the laboratory instructor. Then we must calculate the volume by means of the appropriate gas laws and compare them with the observed volumes. Lastly we will express the differences as percent error. Part B For the molar mass of the vapor we will record the number of the unknown liquid, then place a small square of aluminum foil over the mouth of a clean, dry 125mL erlenmeyer flask. Next we will fold the foil loosely around the neck and secure with a rubber band. Then we will use a pin to make a small hole in the center of the foil. Lastly for the first part we will determine the mass of the flask, foil cap, and rubber band. For the second part we will place about 350mL of water and some boiling chips in a 600mL beaker and begin heating it to bring the water to a boil. While the water is heating, remove the foil from the erlenmeyer flask and place 2mL of the unknown liquid in the flask: then replace the foil and rubber band. Clamp the flask at the bottom of the neck. After the water has been brought to a boil, record the temperature. For the third part, take note of temperature and barometric pressure. For the fourth part, Insert the erlenmeyer flask as far as possible into the boiling water, holding it by hand using the clamp. After about 4 minutes remove the flask from the boiling water and examine it to see whether all of the unknown liquid has vaporized. If not, insert back into the boiling water and assure it does so. After all liquid has vaporized, use the clamp to remove the flask and set it aside to cool. After the flask has cooled to room temperature, wipe it dry and remove any water that adheres to the aluminum. Determine the mask of the flask, cap, rubber band, and condensed liquid. For the fifth part calculate the mass of the condensed liquid. For the final part, remove the cap and fill the flask completely with water. Measure the volume by pouring the water into a large graduated cylinder. Dispose of the condensed liquid in an appropriate waste container and calculate the molar mass of the unknown using M=mRT/PV....