Name: ______________________
Relationship Between Gas Variables
Gas Laws Simulation
Introduction:
Scientists in the late 1800’s noted relationships between various variables related to
gases (pressure, volume, temperature), and the number of gas particles in the sample being
studied. They were able to figure out that it was easier to study relationships if they varied
only two parameters at a time and “fixed” (held constant) the others. For example, they
would study the relationship between pressure and volume (variables) and held
temperature constant (“fixed”). After recording the data and graphic analysis, a trend was
determined.
These experiments would be difficult to complete a laboratory because it is
complicated to isolate the parameters. Using a gas simulation you will be able to create
different scenarios and collect data for each combination. You will be working with a fellow
scientist and determine the various gas laws that were created years ago.
Objectives:
•
•
•
Design experiments to measure the relationships between pressure, volume,
and temperature.
Create graphs based on predictions and observations.
Make qualitative statements about the relationships between pressure, volume,
and temperature using molecular models.
Directions:
Create mini experiments using the Gas Simulation (under my website: “Links”): Following
the instructions below, make observations based on the gas simulation on the website. To
activate the activity, press run now and press keep (bottom of computer).
Do not update Java, press later for the update.
Part I:
Gas Particle Behavior at Constant Temperature
Boyle’s Law
In 1642 Evangelista Torricelli, who had worked as an assistant to Galileo,
conducted a famous experiment demonstrating that the weight of air would
support a column of mercury about 30 inches high in an inverted tube.
Torricelli’s experiment provided the first measurement of indivisible pressure
of air. Robert Boyle, a “skeptical chemist” working in England, was inspired by
Torricelli’s experiment to measure the pressure of air when it was compressed
or expanded. The results of Boyle’s experiments were published in 1662 and became
essentially the first gas law-a mathematical equation describing the relationship between the
volume and pressure of air.
What is Boyle’s law and how can it be demonstrated?
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Directions:
1. Slowly add gas particles to the vessel by raising the pump and bringing it down once.
2. On the right toolbar, make your constant parameter
“temperature.” List the two variables that will be observed in this
activity
Constant Parameter
Temperature
Independent
Variable
Dependent
Variable
________Kelvin
_____________
______________
3. By moving the man on the left and the movable ruler tool (click on tools & options –
measurement tools-ruler), vary the volume and observe the change in pressure.
Make sure you allow the temperature to readjust to the original value.
Complete the following data table based on your observations:
Relationship
VOLUME
Let’s use the width (nm) to
express the volume of the gas.
P vs. V
PV= K
Initial
V= 4 nm
Final
V= 8 nm
Conclusions:
What type of relationship exists
between pressure and volume
(indirect or direct)?
_______________
Label the x-axis and y- axis.
Draw a graph representing the
relationship.
PRESSURE (atm)
Read the pressure gauge
and record the value
Graphic Representation
Practice Problem:
A sample of oxygen gas has a volume of 150.0 mL when its pressure is 0.947 atm. What is
will the volume of the gas be at a pressure of 0.987 atm if the temperature remains
constant? (Using a highlighter, highlight your final answer)
Formula
Mathematical Set-up & Answer
2
Interpret Graphs
Boyle’s Law
Study the line graph below. Volume in liters (L) is on the x-axis. Pressure in kilopascals
(kPa) is on the y-axis. This graph shows the relationship between the pressure and volume
of a gas described by Boyle. The drawings can help you picture the volume of the gas at
specific points. The experiment was done at Standard Temperature.
1. Complete the
table.
Number of
Gas Particles
Pressure
(kPa)
Volume (L)
V1P1
V2P2
V3P3
2. Look at the drawing at point V2P2. What happened to the volume in the cylinder?
___________________________________________________________________________________
What happened to the amount of gas?
___________________________________________________________________________________
3. How did the volume of the gas change between Points V1P1 and V2P2?
____________________________________________________________________________________
How did the pressure change?
____________________________________________________________________________________
4. How does an increase in the volume of a gas affect its pressure? Assume the temperature
is constant.
_________________________________________________________________________________________
____________________________________________________________________________
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5. What would the pressure be if the volume were 1.5 L? ________________
6. Is the relationship between the pressure and volume of a gas a direct one or an inverse
one? _____________________
7. Using the combined Gas Law Formula below cross out the variable that was kept constant
in Boyle’s experiment.
Practice Problems:
a. A gas with a volume of 2.2 L at 140 kPa expands to fill a 4.4-L container. What is
the pressure in the new container? What is the pressure in the new container? The
temperature does not change.
Formula
Mathematical Set-up & Answer
b. A balloon contains 30.0 L of helium gas at 103 kPa. What is the volume of the helium
when the balloon rises to an altitude where the pressure is only 25.0 kPa? (Assume
that the temperature remains constant.)
Formula
Mathematical Set-up & Answer
c. When a piston is pushed down in a cylinder, the pressure on the gas in the cylinder
increases from standard pressure to 3.7 atm. The initial volume is 23.5 L. What is
the final volume?
Formula
Mathematical Set-up & Answer
4
Part II:
Gas Particle Behavior at Constant Pressure
Charles’ Law
Application of the gas laws are important in physiology, meteorology, scuba diving, even hotair ballooning. Charles’s law, which describes how the volume of a gas changes as it is heated
or cooled, was inspired by one of these applications, the first sensational flight in history of
hot –air ballooning.
1. RESET: On the right toolbar, now make your constant parameter “pressure.” List the
two variables that will be observed in this activity.
Constant Parameter
Independent
Dependent
Variable
Variable
Pressure
(Approximate)
__________ atm
_____________
______________
2. Using the thermometer (use the heat control to adjust temperature) and ruler, collect
data to investigate the relationship between volume and temperature of a gas. Make sure
you allow the pressure to readjust to the original value (constant pressure).
TEMPERATURE
Relationship
T vs. V
V/T = K
VOLUME
Let’s use the width (nm) to express
the volume of the gas.
Initial
86 K
__________nm
Final
172 K
__________nm
Conclusions:
What type of relationship exists
between temperature and
volume (indirect or direct)?
_______________
Label the x-axis and y- axis.
Draw a graph representing the
relationship.
Graphic Representation
Practice Problem:
A sample of neon gas occupies a volume of 752 mL at 300 K. What will the gas occupy at
355 K if the pressure remains constant?
Formula
Mathematical Set-up & Answer
5
Interpret Graphs
Charles’s Law
Study the line graph below. This graph shows the relationship between the volume and the
temperature of a gas at constant pressure.
1. Volume is the variable on the y-axis. What units are used for the volume? ___________
2. What is the variable on the x-axis? ___________________ What are the units? __________
3. What is the volume of the gas when the temperature is 300 K? _____________
4. How did the values of the temperature of the gas change between T1 and T2?
_____________________________________________________________________________________
How did the volume change?
_____________________________________________________________________________________
5. When the temperature is 600 K, what is the volume? _____________
6. Use the volume at 600 K to predict the volume at 1200 K. Explain your answer.
(Hint: How did the volume change when the temperature went from 300 K to 600 K?)
__________________________________________________________________________________
______________________________________________________________________
7. How does an increase in the temperature of a gas affect its volume? Assume the pressure
is constant.
_____________________________________________________________________________________
8. Is the relationship between the volume and temperature of a gas a direct or an inverse
relationship? _______________________
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9. Using the combined Gas Law Formula below cross out the variable that was kept
constant in Charles’s experiment.
When you use Charles’s law, the temperatures must be in kelvins!
Practice Problems:
a. An inflated balloon has a volume of 3.85 L at 240C. The balloon is placed in a refrigerator
and cooled to 4.00C. What is the new volume of the balloon? Assume the pressure does not
change.
Formula
Mathematical Set-up & Answer
b. A 6.70 L sample of argon gas is in a cylinder with a piston at STP (standard temperature
and pressure). If the pressure is kept constant, at what temperature will the volume of the
gas be 7.30 L?
Formula
Mathematical Set-up & Answer
c. At 310C, the volume of gas in a small plastic bag is 0.115 L. If you place the bag in a cooler
at 120C, what is the new volume? Assume the pressure is constant.
Formula
Mathematical Set-up & Answer
d. Nitrogen gas is transferred from a 12.1 L container to a 15.2 L container at constant
pressure. The temperature of the gas in the second container is 35.40C. what was the
temperature in the first container?
Formula
Mathematical Set-up & Answer
7
Part III:
Gas Particle Behavior at Constant Volume
Gay- Lussac’s Law
Gay-Lussac grew up during the period of the French Revolution. This was a time when the
science of chemistry also saw several changes. The French Revolution directly affected GayLussac. During the revolution, his father was imprisoned and young Gay-Lussac was sent to
the Ecole Polytechnique. This was an institution created by the French Revolution to nurture
scientists, especially for military use.
1. RESET: On the right toolbar, now make your constant parameter
“Volume.” List the two variables that will be observed in this activity
Constant Parameter
Volume
Variable #1
Variable #2
_____________
______________
.
Relationship
T Vs. P
P/T = K
Temperature
Initial
Final
What type of relationship exists
between temperature and
pressure (indirect or direct)?
_______________
Label the x-axis and y- axis.
Draw a graph representing the
relationship.
Pressure (atm)
(Approximate)
40 K
80 K
Graphic Representation
Questions:
1. Using the combined Gas Law Formula below cross out the variable that was kept
constant in Gay Lussac’s experiment.
When you use Gay-Lussac’s law, the temperatures must be in
kelvins!
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As the temperature of an enclosed gas
increases, the pressure increases, if the volume
is constant.
Practice Problems:
a. The gas in a container is at a pressure of 3.00 atm at 298 K. Directions on the container
warn the user not to keep it in a place where the temperature exceeds 325 K. What would
the gas pressure in the container be at 325 K?
Formula
Mathematical Set-up & Answer
b. Aerosol cans carry labels warning not to incinerate (burn) the cans or store them above a
certain temperature. This problem will show why it is dangerous to dispose of aerosol cans in
a fire. The gas in a used aerosol can is at a pressure of 103 kPa at 25oC. If the can is thrown
onto a fire, what will the pressure be when the temperature reaches 928oC?
Formula
Mathematical Set-up & Answer
c. A pressure cooker containing kale and some water starts at 298 K and 101 kPa. The
cooker is heated, and the pressure increases to 136 kPa. What is the final temperature inside
the cooker?
Formula
Mathematical Set-up & Answer
9
Using the Combined Gas Law Formula
1. A beach ball is partly inflated to a volume of 23.3 L. The temperature of the air in the ball
is 305 K, and its pressure is 101.3 kPa. A swimmer holds the ball under water in a pool,
where the pressure is 131.3 kPa. The volume of air in the ball decreases to 17.6 L. What
happens to the temperature of the air in the ball?
Formula
Mathematical Set-up & Answer
2. Neon gas at STP is compressed in a rigid container to a volume of 84.6 L. What is the
pressure of this gas at 88.5 L and 250C?
Formula
Mathematical Set-up & Answer
3. A gas has a volume of 275 L at 348 K. When it is cooled to 297 K, its pressure changes to
115 kPa and its volume decreases to 263 L. What was the original pressure of the gas?
Formula
Mathematical Set-up & Answer
10
Part IV:
Number of Gas Particles(Moles) and Volume: Temperature and Pressure
Avogadro’s Law
This simulation cannot be performed.
Therefore, predict the relationship. Since volume is one of the variables, that means the
container holding the gas is flexible in some way and can expand or contract.
Relationship
Number of gas
molecules(moles)
versus
What happens to the volume of a balloon when
helium from a tank is added to the balloon?
____________________________________________________
Volume
V=kn
* n is the amount of
gas in moles
What type of relationship exists
between volume and number of
moles (indirect or direct)?
_______________
Label the x-axis and y- axis.
Draw a graph representing the
relationship.
Graphic Representation
Avogadro’s law states that equal volumes of gases at the same temperature
and pressure contain equal numbers of molecules.
Practice Question:
Which gas sample at STP has the same total number of molecules as 2.0 liters of CO2(g) at
STP?
(1) 5.0 L of CO2(g)
(3) 3.0 L of H2S(g)
(2) 2.0 L of Cl2(g)
(4) 6.0 L of He(g)
Which gas sample at STP has the same number of molecules as a 2.0-liter sample of Cl2(g) at
STP?
(1) 1.0 L of NH3(g)
(3) 3.0 L of CO2(g)
(2) 2.0 L of CH4(g)
(4) 4.0 L of NO(g)
Using dimensional analysis, determine the volume of 3 moles of neon gas at STP?
(Equivalence statement: 1 mole of any gas at STP = 22.4 L)
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Making Connections:
Using your results, explain each of the following scenarios. Make sure to refer to which
graph can be used as evidence for your answer. Also include references to pressure,
temperature, and volume in your responses.
1. In terms of gas particle behavior, explain why bicycle tires seem more flat in the winter
than in the summer.
2. Explain why a can of soda pop explodes if left in the hot sun.
3. A rigid container filled with a gas is placed in ice (example: Oxygen tank found in
hospitals). What will happen to the pressure of the gas inside the tank?
4. An infected tooth forms an abscess (area of infected tissue) that fills with gas. The
abscess puts pressure on the nerve of the tooth, causing a toothache.
While waiting to see a dentist, the person with the toothache tried to
relieve the pain by treating the infected area with moist heat. Will this
treatment help? Why or why not?
5. Lungs expand as they fill with air. Exhaling decreases the volume of the lungs. Describe
the law that explains this biological function?
.
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