Purpose:To determine the relationship between volume of a gas and temperature of a gas.
Background:Hot Air Balloons. Always beautiful to watch, but what makes them fly? Charles' Law helps to explain some of the mechanism of ballooning, and yet doing experiments to illustrate Charles' Law are often difficult.
The classic technique is to use a small volume of gas with a long tube that was topped by a plug of mercury. The mercury would rise and lower as the volume of the gas changed. Since the top of the tube was open to the air, pressure inside and outside the gas were the same. As long as air pressure in the lab didn't change, the air pressure in the gas sample didn't change.
Procedure:Although you will be working with a lab partner in gathering your data and typing your results, you will each record your own data into your own lab notebook. Be sure to start your notebook entry with a summary of this experiment.
- 1. Begin by predicting what you think the relationship between Volume and Temperature is. Then predict what the graph will look like by drawing a sketch in your notebook.
- 2. Create a data table in your notebook with two columns, one for Volume (ml), the other for Temperature (K).
- 3. Open the website linked in the background. Record the current temperature and volume for the gas sample in your data table.
- 4. Use the sliding control in the animation to change the temperature. Once the temperature has stabilized and the piston has stopped moving, record the new temperature and volume.
- 5. Continue changing the temperature, being sure to get as many different temperatures and volumes as you can. At least 10 data points are required. Temperatures should have at least 10 K difference between them.
- 6. Minimize the browser, then open LoggerPro. Whichever lab partner was not manipulating the animation should now be typing in LoggerPro.
- 7. Give the two data columns labels and units (like your notebook data table).
- 8. Type the data into your LoggerPro data table. Give your graph a title that illustrates what the data is showing. (“Charles' Law” for example.)
- 9. Add a Linear Fit to your graph (using Analyze and Linear Fit). Move the Linear Fit box so that it isn't obscuring any of your data, save your LoggerPro file (save it in your shared folder so that both lab partners can access it), and copy your graph.
Questions:Swap typists again. Open a Word Document. Give the page a title and type in you and your partner's names. Once you paste in your graph, answer the following questions using complete sentences.
- 1. Describe how well you and your partner did in your predictions. It is possible that someone was correct for one part of the prediction, but wrong with the other. It is also possible that you and your partner did not have the same prediction.
- 2. State what the relationship between Volume and Temperature is, according to your data. Are they directly proportional, inversely proportional, proportional by the square or some other relationship?
- 3. Most lines have both a slope and a y-intercept. The value of the slope isn't important for us right now, but state what the y-intercept is, according to the Linear Fit box in your graph. How close is this value to absolute zero?
- 4. Since X is Volume, the y-intercept occurs when Volume is Zero. Can a gas have a volume of zero? Explain your thoughts in this matter on why or why not.
- 5. Although this is a computer simulation, there are still chances for error in measurement and in the apparatus itself. Discuss what these sources of error likely are. Be specific.
Turning in the Assignment:When you are finished, double check that your sentences are complete, and that none of them start with “Yes” or “No.” The save the file in your shared folder with the name X-XX-Charles Law, where X-XX is Per#-Group#. Once saved, close Word, then drag and drop a copy of this file into the Turn In folder.