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 will be air, and it will be confined in a syringe connected to a pressure
sensor. When the volume of the syringe is changed by moving the piston, a change occurs in the pressure
exerted by the confined gas. This pressure change will be monitored using a pressure sensor. It is assumed that
temperature and amount of gas will remain constant throughout the experiment. Pressure and volume data pairs
will be collected during this experiment and then analyzed. From the data you will create a graph and determine
the mathematical relationship that exists between the pressure and volume of a confined gas. This relationship
was first established by Robert Boyle in 1662 and has since been known as Boyle’s Law.
Procedure:
1.
With the syringe disconnected from the sensor, move the piston of the syringe until the front edge of
the inside black ring is positioned at the 10.0 mL mark.
2. Attach the syringe to the pressure sensor by gently twisting/turning the syringe onto the sensor
3. On the computer, open the “Logger Pro” program on the computer. After the program is opened you
should see pressure values listed in the lower left corner of the screen.
4. For this lab, it is best if one person is in charge of the syringe and the other person records the data:
a. Record the pressure when the syringe is at a volume of 10.0 mL
b. Move the piston to a different volume and record the pressure and volume at this location.
c. Continue to record volume and pressure values in order to record a total of 6 different points
Making your Data Table and Graph:
Trial
1
2
3
4
5
6
Volume of Gas (mL)
10.0 mL
Pressure (kPa)
1/Volume
1. In the 4th column, find the inverse for your volume measurements (1/volume).
2. Create a graph of the relationship of pressure (on the y- axis) as a function of the inverse volume (or
“1/volume”) on the x-axis. Determine the equation of the line for this relationship. (See back of page
for directions)
Analysis: (Answer the following on the back of your graph!)
1. Provide an explanation of what is happening at the microscopic level when the piston moves from the
10.0 mL mark to the 5.0mL mark. Your answer should explain why the pressure increases or decreases
as the piston moves if the number of molecules present has not changed.
Supplemental Information:
To create a graph in Microsoft 2007:
1. Enter your data into the spreadsheet with one column being your temperature data and another column
having your 1/volume data.
2. Highlight a column containing data.
3. Create a graph by selecting “insert” and chose the “x-y scatter plot” where the lines are not drawn (only
dots are visible).
4. A graph will automatically appear. Make sure your correct values are on the x and y axis. If they are
not correct you must do the following:
a. Right click on the center of the graph (not on a point). Chose to “select data”
b. Remove the series from the bottom right box by choosing “remove”
c. Select the “add” option
d. A small box will be displayed that has a place for data on the x and y axis. To the right of the xaxis box, click on the small icon that looks like an arrow in graph paper. This will take you
back to your data table where you will highlight the x-axis values. After selecting the correct
values, click the small box with the arrow to bring you back to the original data input screen.
Complete this same step for the y-axis values.
e. After you have selected your data continue to click “ok” until you have displayed your graph.
5. You may add a title to your graph and label each axis by choosing the “layout” tab and selecting the
Title button and selecting an option of where you would like to put the title. Then you can click on the
generic title to create your own more specific title.
6. To create the line of best fit you must right click on one of your points and chose “add trendline”
a. Click on the picture which best describes your graph. (Look at the slope (or curve) of the line
and not the direction of the curve!) Your graph will most likely display a linear relationship
b. Make sure the “automatic” equation of the line is selected. Also click on the box labeled as
“show equation” and “show r squared value” in order to display the equation on your graph.
Creating a graph in Excel 2003:
1. Enter your data into the spreadsheet with one column being your temperature data and another column
having your volume data.
2. Highlight a column containing data.
3. Click on the “insert” tab and select “chart”
4. Select the “xy scatter” plot (the box highlighted on the right should contain only dots and no lines).
5. Click next
6. Select the “series” tab and select to “remove” all the values. Then chose the “add” to precisely add your
data into the graph.
7. Click on the small box (the box shows a data sheet with a red arrow) to the right of the “X values”
8. Highlight your x-values and click the small gray box on the far right of the small window.
9. Continue with steps 7-8 for inputting your y-values
10. Select “next” and enter the appropriate title and labels. Click finish when you are done.
11. Now you must resize both axes. Right click on the y-axis and select “format axis”
12. Now you must determine the equation of your line. Analyze your data points and create a best-fit line
through your data points. Right click on one of your data points and chose ‘add trendline’. Select the
power trendline (this graph should best fit your data) and then click on the options tab. Here you must
select to “display equation on chart” and display “r-squared value”.