HOME

LESSON PLANS

BIOGRAPHY

BOSTON UNIVERSITY

LESSON 5: Boyle's Law

Subject Area

Grade

Estimated Length

Prerequisite knowledge/skills

1. Basic knowledge of Boyle's Law

Description of new content

Goals

The purpose of this lab is to verify Boyle’s Law using applied force to do work on a closed isolated system of air. A syringe apparatus is to be used to measure volume change as a function of applied force (weight).

Materials Needed

Each student or group should have 1 "Elasticity of Gases Apparatus, BASIX". This apparatus can be purchased from the Sargent-Welch catalog for $13.50 each.

Procedure

The following assumptions will be made.
1) The pressure in the atmosphere today is 1 atm (101.3 kPa).
2) The air functions as an ideal gas at the pressures and temperatures of the experiment.
3) No air can leak out of the syringe during the experiment.

Perform the following measurements:

1) Remove the plunger and upper block (the thinner of the two wooden blocks) and measure the mass of both. Record the mass value here in (kg): ______________

2) Measure the diameter of the plunger face. Record the diameter here in (m): _______________

3) Reassemble the syringe and plunger and turn them over so that the outlet of the syringe faces down and the plunger faces up. Observe whether or not the plunger stays up in the syringe or falls down to the bottom of the syringe. Describe your observations.

4) To begin the experiment, pull the plunger up to some constant and measurable volume and place the red cover over the end of the syringe. This will be your starting volume (V1). Record your starting volume here in (cc): ______________

5) Place the closed syringe apparatus upside down so that the red cover faces down on the table and use the provided masses to fill in the following table of volume vs. added mass.

Assessment Questions:

1) Based on the data you obtained, and your knowledge of the ideal gas law, what type of graph (function) would you expect to see on a PV graph of this data?

2) Using your answer to number one, above, on a separate sheet of graph paper draw a PV diagram using your data and draw a best fit function to the data.

3) Based on the assumption of room temperature gas (293K) estimate the number of moles of air that is present in the syringe using the ideal gas law and your PV data and/or graph.

4) Using the generated graph, calculate the work done on the gas by the weights you added to the syringe apparatus.

5) What errors were present in this experiment that could have skewed the actual values of volume to the calculated values. Hint: Consider the syringe itself and how it works, the assumptions we made, and how the measurements were taken.