PHY202: General Physics II Lab page 1 of 3
Instructor: Tony Zable
File Name: Ph202_lab-Boyles-Law-w09.doc
Experiment: Boyle’s Law
PART I: Pressure-Volume Relationship in Gases (Boyle’s Law)
INTRODUCTION
The primary objective of this experiment is to determine the relationship between the pressure
and volume of a confined gas. The gas we use will be air, and it will be confined in a syringe
connected to a pressure sensor (see Figure 1). According to the Ideal Gas Law for an enclosed
gas (with n particles), the product of gas pressure (P) and volume (V) should be a constant
value at constant temperature (T) or:
PV = nRT = constant {when n & T are cons
tant}
where R = 8.31 J/mol
.
K is called the Universal Gas Constant.
In Figure 1, when the volume of the syringe is changed by moving the piston in or out, a
corresponding change in the pressure exerted by the confined gas should result. This pressure
change will be monitored using a pressure sensor. It is assumed that temperature will be
constant throughout the experiment. Pressure and volume data pairs will be collected during
this experiment and then analyzed with LoggerPro. From the data and graph, the
mathematical relationship between the pressure and volume of the confined gas will be
identified. Historically, this relationship was first established by Robert Boyle in 1662 and has
since been known as Boyle’s law.
Pressure Sensor
Figure 1
PRELIMINARY QUESTIONS
1. Obtain a small syringe and position the plunger at about the midway point. Place a closed
stopcock over the small opening. Gently push the plunger inward about ½ mL. Next press the
plunger further into the syringe (2 or 3 mL). How does the effort to press the plunger a short
distance into the syringe compare to pressing it further?
2. Now, gently pull the plunger outward about ½ mL. then pull the plunger further outward (2
or 3 mL). How does the effort to pull the plunger a short distance out of the syringe compare
to pulling it further?
3. Based on your observations above, what you say about the relationship between push/pull
force and volume for an enclosed gas? Between pressure and volume?
