Boyle’s Law Lab – The Pressure and Volume Relationship of a Confined Gas
Purpose: To understand the relationship between the pressure and volume of an enclosed gas.
Introduction:
The gas we are using today is ordinary room air. You will confine a sample of air within a 60 cc syringe barrel. Then, by using the lined “1cc” markings on the syringe, you will record the volume of the air as you make adjustments with the plunger. A pressure sensor connected to the end of the syringe will enable you to measure the pressure, in kiloPascals, “kPa”, of the air at each volume you choose.
Your data will be graphed automatically, asPressure (kPa) on the y-axis, and Volume (cc) on the x-axis. By understanding this graph, you will be able to understand the mathematical relationship that exists between the pressure and volume of any confined gas, as long as the temperature remains constant. This relationship exists for any gas, not just room air. Historically, this relationship was established first by Robert Boyle, and is thus referred to as “Boyle’s Law”.
Materials:
1 labpro interface with attached pressure sensor. 1 60-mL plastic syringe.
Software Setup:
1.Log on to computer.
2.Either double click on the desk top shortcut for LoggerPro 3.8; or access it through the start menu: Start Science Department Chemistry Lab LoggerPro 3.8
- Click on the open folder icon
2. Click on the open folder icon (top toolbar). Select “Chemistry With Vernier”. Select Experiment 06 Boyle’s Law
3.
Connecting the syringe to the pressure sensor: WAIT FOR YOUR TEACHER TO CONNECT IT....
If not yet done, your teacher will come around to hook up your 60-mL syringe so that the bottom edge of the black plunger is positioned at the 10 cc mark on the syringe barrel.
IMPORTANT – Please do NOT move the position of the blue plastic lever at the base of the syringe. Please be careful - your data won’t be correct if the blue lever moves after data collection is begun; also, your data won’t be correct if you push too hard on the syringe barrel and it “pops”.
Experimental Procedure (Data Collection): *Checkon the computer that “number lock” is on.
Just before you actually begin -- Click only once on the green “Collect” arrow located on the computer screen. [Don’t click on the green arrow again!] A red dot should shortly appear on the screen.
Divide up the jobs- someonecould manipulatethe syringe. This is harder than it sounds.
Someone else could type in each syringe volume when needed.
Someone eksecould click on the blue “keep” button, and on the OK button when needed.
When everyone is ready, do the following:
-Hold the syringe barrel at exactly 10.0 cc. Click “keep”. Enter 10.0 for the volume. Click “OK”.
Notice how the volume and pressure readings automatically appeared in the table and graph! If this does not happen, then you have done something incorrectly….You probably didn’t click the green “collect” arrow. Try again.
READ ALL OF THE NEXT PARAGRAPH BEFORE CONTINUING--
For the remaining data points, move the syringe barrel to a different volume, click OK, type in the volume, and click “keep”, etc. Each time, observe how the graph reflects the newly entered data points. You will be able to tell when you’ve made a mistake (most likely the person wasn’t able to hold the syringe at that volume long enough). You will need to remove a data point if it is obviously incorrect. Most importantly, please stay within the volume range of 3.5 – 40.0 cc.Tell your teacher if the syringe “pops”before you get through with collecting10 data points. You must include these 4 volumes: 5, 10, 15, and 20 cc. As you collect the data for these points, fill in the table below.
Then, if you want to, try to get some extra data points at 3.0, 2.5, and finally 2.0 cc; but, if the syringe “pops”, you should not keep that data point. When finished collecting data, click on the red “stop”.
Analyzing the Graph: Make sure you already clicked on the red stop button.
-Click once on the Pressure vs Volume graph to select it.
-Click on “analyze” “curve fit” scroll down to “A/x (inverse)”. Click on “Try Fit”, then “OK”.
-If the pop up information box is in the way, move it to the side. [Careful, don’t close the box.]
- If the pop-up box says “waiting…”, OR it doesn’t draw the line -You probably didn’t click the red “stop” button. Try again.
Print one GRAPH for each member of your group, plus one extra for your teacher.File “Page Setup”: Check landscape. Then, File Print. Click OK.
Volume (cc) / Pressure (kPa)5
10
15
20
Please use the graph and/or data table to answer these questions; re-read the introduction as necessary:
1. As volume goes down, what happens to the pressure of the air within the syringe barrel?
2. As volume goes up, what happens to the pressure of the air within the syringe barrel?
3. Would you expect to see the same, or a different, relationship, if you used a gas other than air?
4. What important environmental condition was held constant during this lab?
5. From the shape of your P vs V graph, is the relationship between the pressure and volume of a confined gas (when temperature is constant) “directly proportional” or “indirectly proportional”? [Another term for indirect is “inverse”.]