Gas pressure vs gas volume relationship
Homework - Prelab concept review (study the following information)
In your 6th grade science class:
•
You learned to, “Compare the composition and structure of Earth’s atmospheric
layers (including the gases and differences in temperature and pressure within the
layer.”)
Standard 6-4; Indicator 6.4.1;
South Carolina Science
Academic Standards
In your physical science class:
•
You learned about the “…various properties and classifications of matter.”
•
You learned to, “Compare the properties of the four states of matter—solid,
liquid, gas, and plasma—in terms of the arrangement and movement of
particles.”
•
You learned about force “…the relationship among force, mass, and
acceleration; and action and reaction forces”; the formula F = ma; and “the
relationship between mass and weight by using the formula FW = mag.”
Here is what you must know/recall in preparation for the Boyle’s law lab activity:
Standard PS-3; South Carolina
Science Academic Standards
Standard PS-3; Indicator PS-3.6;
South Carolina Science
Academic Standards
Standard PS-5; Indicator PS-5.7,
5.8, and 5.9; South Carolina
Science Academic Standards
Pressure:
Definition - Pressure (P) is force (F) applied to an area (A). This means that P = F × A.
Connection with physical science: Put your finger on the fingerprint image to the right. When you do
that you are applying a force (F = ma) to the surface of the paper in the area under your finger: P
= F × A. Your body mass combined with the action of gravity (FW = mag) are exerting a pressure
on the floor you are standing on or the chair in which you are sitting: P = F × A.
Connection with 6th grade science: The pressure of gases (such as all the gases in the air in the atmosphere) is
the result of millions of gas molecules randomly hitting against a surface. One molecule hitting a surface
would not result in a lot of pressure, but the combined effect of millions, billions, trillions, or quadrillions
of molecules hitting a surface in rapid succession can result in a lot of pressure.
Big numbers: About 2.5 septillion molecules (that’s 2.5 × 1024 molecules) strike the surface of your body
every second. All those molecules hit your body with an average velocity of about 1.5 kilometers per
second (that’s more than 2,000 miles per hour).
Structure of gases:
The online version of Encyclopædia Britannica states, “The remarkable feature of gases is that they appear to
have no structure at all” (http://www.britannica.com/EBchecked/topic/226306/gas/51924/ Structure; accessed
01-Apr-11). After all, gases don’t have a shape (gases take the shape of their container), and they don’t have a
fixed volume (gases fill the space of their container).
So, what do we mean by the structure of gases? When we say structure when referring to gases, we are
talking about the way that the particles are arranged. These particles can be atoms or they can be molecules.
The particles in the gaseous diatomic elements (hydrogen, nitrogen, oxygen, fluorine, and chlorine) all form
these diatomic molecules in their pure form at lab temperature and pressure (LTP). Carbon dioxide is gas
made of molecules at LTP. The particles in the noble gases (helium, neon, argon, krypton, and xenon) are
atoms. The particles in a gas for moving very fast (~1.5 km/sec at LTP). The particles in a gas hit each other
and hit against any solid or liquid surface and—for the most part—just bounce off.
Analysis of patterns on graphs:
If you do not recall the names of 2 patterns from unit 1, go back to your unit 1 notes and review.
PreLab Video:
Watch the YouTube video on this lab BEFORE coming to class:
https://youtu.be/wyL0ruzeWyw?list=PLigm3D2yYJ1vfSoofQukufRWdW8C-buTS
Gas pressure vs gas volume relationship
Inquiry lab activity: 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 Gas Pressure Sensor (see Figure 1). 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 Gas 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. From the data and graph, you should be able to
determine what kind of mathematical relationship exists between the pressure and volume of the confined gas.
Write these procedures in your lab notebook in pen. Then go to the lab. Wear all required safety gear.
You do NOT have to work with your share partner. During lab be sure to write careful observations and
measurements.
PROCEDURE (these procedures MUST be summarized in
your lab log book BEFORE coming to class on the day of this lab)
Lab set up
1. Prepare the Gas Pressure Sensor and an air
sample for data collection.
a. Connect the Gas Pressure Sensor to
LabQuest and choose New from the File
menu.
b. With the 20 mL syringe disconnected
from the Gas Pressure Sensor, move the
piston of the syringe until the front edge
of the inside black ring (indicated by the
arrow in Figure 1) is positioned at the
10.0 mL mark.
c. Attach the 20 mL syringe to the valve of
the Gas Pressure Sensor.
Figure 1. The syringe connected to the gas pressure sensor.
The cable from the gas pressure sensor will be connected to
the LabQuest unit. You will it into one of the ports along the
top of the LabQuest. Take not the arrow in the illustration.
That arrow shows were to measure the volume of air in the
syringe. The plunger in the syringe has 2 “rings.” You will
measure the volume from the ring that is closest to where the
syringe is attached to the gas pressure sensor.
d. Plug the cord from the gas pressure
sensor into the top of the Lab Quest.
e. Connect the Lab Quest to the computer
with a USB cable.
f. Plug the power cable for the Lab Quest
into the plug on the side of the lab table
and into the Lab Quest.
g. Turn the Lab Quest on using the shiny
oval button.
2. Set up the data-collection mode.
a. On the computer, click the start button.
b. Click “Student Menu” in the dialogue
box.
c. Click “Logger Pro” in the 2nd dialogue
box.
d. On the Logger Pro tool bar, click the
folder button.
e. Click “My Computer.”
f.
Click “dhsstudentwork$ on ‘dhsfs01’(N:)”
g. Click Vernier Lab
Figure 2. The LabQuest unit. Your gas pressure sensor will be
plugged into this unit and this unit will be connected to a
computer using a USB cable.
Gas pressure vs volume relationship
h. Click “Chemistry with Vernier”
i. Click “Boyle’s Law”
j.
Double click the title and change the title to the format that you have been taught in this class. The title
should follow this format: The effect of (the independent variable) on the (dependent variable) for (the
thing or stuff you are working with).”
k. Right click on the horizontal axis label, then click on “Column Options,” then click on the “Latest
Volume” or “Latest Pressure” and change the title of both axes to the appropriate form for this class.
l.
Select OK.
3. Stop! Return to your desk and prepare to leave the classroom for a whole class activity in the hallway.
Lab - Data collection
You are now ready to collect pressure and volume data. Make sure that you write your observations
(including all the measurements, in your lab notebook). Make sure that what you write is clear and
complete to a reader. It is not enough to enter the lab measurements into the computer. You must be able
to recreate the entire lab from the information in your lab notebook, including recreating a table of data if
necessary.
4. Click
to begin data collection.
5. Collect the pressure vs. volume data. It is best for one person to operate the gas syringe and for another to
operate the computer.
a. Move the piston to position the front edge of the inside black ring (see Figure 1) at the
5.0 mL line on the syringe. Hold the piston firmly in this position until the pressure value stabilizes.
b. To obtain the best data possible, you will need to correct the volume readings from the syringe. Look at
the syringe; its scale reports its own internal volume. However, that volume is not the total volume of
trapped air in your system since there is a little bit of space inside the pressure sensor.
c. To account for the extra volume in the system (inside the Gas Pressure Sensor), you will need to add
0.8 mL to your syringe readings. For example, with a 5.0 mL syringe volume, the total volume would
be 5.8 mL. It is this total volume that you will need for the analysis.
Note: Due to extra air volume inside the sensor and in the syringe tip, the true gas volume is
about 0.8 mL greater than the volume indicated on the syringe. You MUST add this value to
each volume you enter into the table on the computer. You MUST also list BOTH volumes
(the volume on the syringe and the volume on the syringe plus 0.8 mL) in your lab notebook.
Make sure that they notes in your lab notebook indicate why you are listing 2 volumes.
d. When the pressure reading has stabilized, click
. Type 5.8 in the edit box. Press the ENTER
key to keep this data pair. DO NOT press or click the
button until you have collected ALL
your data. Note: You can choose to redo a point by pressing the ESC key (after clicking
, but
before entering a value).
e. Continue the procedure for volumes of 7.0, 9.0, 11.0, 13.0, 15.0, 17.0, and 19.0 mL.
f.
6.
Click
when you have finished collecting data.
Examine the graph of pressure vs. volume. Based on this graph, decide what kind of mathematical relationship
you think exists between these two variables, direct or inverse. To see if you made the right choice:
a.
Click the Curve Fit button,
.
b.
Choose Variable Power (y = Ax^n) from the list at the lower left. Enter the power value, n, in the
Power edit box that represents the relationship shown in the graph (e.g., type “1” if direct, “–1” if
inverse). Click
.
c.
A best-fit curve will be displayed on the graph. If you made the correct choice, the curve should match
up well with the points. If the curve does not match up well, try a different exponent and click
again. When the curve has a good fit with the data points, then click
.
Gas pressure vs volume relationship
Post Lab – In-class Data Reporting and Conclusion
7. Save your completed graph to your personal flash drive. You can download and use the LoggerPro software on
your home computer by using the links below.
Logger Pro 3.8.6.2 with sample movies (Windows)
Logger Pro 3.8.6.2 with sample movies (Mac OS X)
Link: http://www.vernier.com/d/zyeaq
Link: http://www.vernier.com/d/rlskp
Password: ecosystem
Password: ecosystem
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Detailed Step-by-Step Guide
Do you need more detailed instructions on how to download and install our software? Please read our detailed download instructions online:
http://www.vernier.com/til/2069/ .
8. Open your Google folder. Open your “Boyle's Law Spreadsheet.” Highlight and copy the data (measurements)
in the Vernier Logger Pro table, click CTRL C on your keyboard to copy the data. Click cell A2 in the
Google “Boyle's Law Spreadsheet.” Click CTRL V on your keyboard to paste the data. Highlight all the
cells in your spreadsheet including the 2 blank ones at the top. Click CTRL C on your keyboard to copy the
table. Open your “Boyle's Law Post Lab Report” in your Google folder. Click your return button a few times
(your left arrow button) at least once to
to leave space at the top of your document for later work. Click
leave a space below. Click CTRL V on your keyboard to paste the table into your report.
a. The blank cells in your table are there so that you can write column labels in your post lab document.
Recall that you MUST have a table label and column labels to have a complete table
9. Click on the Vernier Logger Pro graph. Click CTRL C on your keyboard to copy the graph. Open your
“Boyle's Law Post Lab Report” in your Google folder. Hit Click CTRL V on your keyboard to paste the
graph into your report.
Note: If your graph will not paste into your Google doc, paste it into a Microsoft Word document first,
copy the graph from the Word document and paste it into the Google document.
Post Lab – After-class Data Reporting and Conclusion
10. Once your table data and incomplete graph are pasted into your report, you are done for this lab period. You
will finish your report at home, in the library/media center, or in the lab outside of class time.
In your Boyle’s Law Post Lab report (in Google Docs or Google Drive)
11. You must include an introductory paragraph explaining—in your words—the purpose of this lab. This
introduction must include a heading.
12. Your table and graph is the part of a lab report called the Results section. This results section must include a
heading.
13. Your table must be completed (the table label and column labels must be complete).
14. Your graph must be completed (the figure label must be completed).
15. You must include a Conclusion section. The conclusion should briefly summarize how the lab was performed
and should include an explanation of what the measurements and the analysis (pattern) from the graph shows
about gas pressure and volume behavior. This conclusion must include a heading.