Determination of Boyle's Law through Data Collection

Students will determine Boyle's law by using various numbers of textbooks on syringes to change the pressure and record the volume. They will calculate force using the equation F=ma and then convert it to pressure. They make two graphs: P vs. V and P vs. 1/V. In this way, students see the indirect relationship between pressure and volume. They are also able to determine a mathematical relationship using the straight-line formula with the second graph resulting in PV = constant.
Students will review/discover terms:
Force
Pressure
Volume
direct and indirect relationships

This activity has been used with students in high school chemistry class. It is a lab activity, although data collection can be completed in a 45 minute class period. The analysis and graphing will take additional time. For each small group (2-4students) you will need a 100 mL syringe with the tip sealed. This lab is used as an introduction to gas laws. Students have been introduced to kinetic theory of gases. This activity could be adapted easily by either adding more or less direction in the development of the gas law in the analysis as the data collection is very straightforward.

Students are given the hand-out (see attachment) and shown the set up. Materials needed for each small group include a sealed syringe, ring stand, test tube clamp, 5 textbooks (the same if possible), ruler, and access to a scale. Students will record the initial volume on the syringe and then add a book. They will record the resulting volume and repeat this after adding additional books on top of the syringe. Once they have repeated the data collection two times they have several calculations to complete in order to convert the mass of the books to pressure on the syringe (see attachment). Discussion of how force is related to pressure is outlined in attached notes. Student hand out for Boyle's Law Lab (Microsoft Word 84kB Aug25 09) Teacher/Student notes on conversion of force to pressure (Microsoft Word 48kB Aug25 09)

It is helpful to zero the syringe before starting each data collection. To do this you can place a piece of copper wire over the stopper of the syringe. You can zero the stopper and then pull the copper wire out. Also, students need to be careful about books falling off the top of the syringe. They should try to steady the books but not hold them while recording data.

Students will turn in raw data, calculations, graphs, and answers to analysis questions.

9C.2.1.4.2

Explain changes in temperature, pressure, volume and number of particles of a gas in terms of the random motion of molecules in an ideal gas.