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Chemistry!
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Chemistry!
istry!
P1V1 = P2V2
T1
T2
Gas Law Book
Topic
Page Number
Kinetic Molecular Theory
2
Pressure
2
Boyle’s Law
5
Charles’s Law
8
Gay-Lussac’s Law
11
Combined Gas Law
13
Mixed Practice
15
Gas Properties Simulation
17
Dalton’s Law of Partial Pressures
18
Ideal Gas Law
19
1
Kinetic Molecular Theory
“The tiny particles in all forms of matter are in constant motion.”
What does this mean for a gas?
Here are the postulates of the Kinetic Molecular Theory.
1)
All gases particles are in constant and random motion.
2) There are no sources of attractions or repulsion among gas
particles.
3) The collision of these gas particles with an object results in gas
pressure.
4) The average kinetic energy of these gas particles is directly
related to their absolute temperature.
Pressure
1. What is the definition of pressure?
2. What causes pressure?
3. What are the units used to measure pressure?
2
4. How do I convert between units of pressure?
atm =
mmHg =
kPa =
psi
5. How many kilopascals are equivalent to 880 mmHg?
6. Calculate the number of pounds per square inch(psi) that are in
2.60atm.
Practice Problems on Pressure Conversions
Show all work! Record your answer with the correct number of significant
figures and units!
1. Calculate the pressure of 1.30 atm in mmHg.
2. Convert 56kPa to psi.
3. How many atmospheres are equivalent to 230kPa?
3
Just to Review…
o
C + 273 = K
4. What is 560. K on the Celsius scale?
5. Water boils at 100. oC. What is the boiling point of water in Kelvin?
4
Boyle’s Law
Magnet Summary
State Boyle’s Law.
General Graph for Boyle’s Law
Equation for Boyle’s Law
Boyle’s Law
Inverse or Direct?
Example Problems
1. The pressure of a 3.5L balloon was determined to be 1.5atm. Assuming that
the temperature remained constant, what would be the volume of the balloon
if the pressure was decreased to 0.45atm?
2. At 45oC, a certain container of gas has the volume of 580mL and a pressure
of 980mmHg. What would be the new volume of the gas at 250 mmHg and
45oC?
5
Boyle’s Law Practice Problems
Be sure to show all work. For every problem, report your answer with the correct number of significant
figures and the correct units!
1. A hot air balloon contains 30.0 L of helium gas at 103 kPa. What is the volume of the
balloon when it rises to an altitude where the pressure is only 25.0 kPa? Assume that the
temperature remains constant.
2. The pressure on anesthetic gas changes from 15.0 atm to 6.00 atm. If the original
volume was 12.0L, what will be the new volume of the anesthetic gas after the pressure
has been decreased?
3. A gas with a volume of 4.00 L at a pressure of 205 kPa is allowed to expand to a volume
of 12.0 L. If this occurs at a constant temperature, what is the pressure in the container
after the expansion?
6
4. Your blood contains 2.00 L of N2 at 1.00 atm. When you go scuba diving at the Great
Barrier Reef, the pressure increases to 8.70 atm. What is the new volume of N2 gas in
your blood stream? Watch out for the sharks!
5. A can of coke contains 25.0 mL of carbon dioxide gas at 100. kPa. If you take it on a hike
up Mount Everest and the pressure decreases to 50.0 kPa, what will the new volume of
the carbon dioxide gas in your coke can be?
7
Charles’s Law
Magnet Summary
General Graph for Charles’s Law
State Charles’s Law.
0
Equation for Charles’s Law
Charles’s Law
Inverse or Direct?
Temperature must be in
.
EXAMPLE PROBLEMS
1. The temperature of a 0.65L sample of carbon dioxide gas is 580K. If the
pressure remains constant, what is the new volume of the gas if the
temperature increases to 1300K?
2. A balloon has a volume of 5.6L at a temperature of 98oC. If the volume of
balloon increases to 9.5L, what will be the temperature of the gas in Celsius?
Assume that the pressure remains constant.
8
Charles’s Law Practice Problems
Be sure to show all work. For every problem, report your answer with the correct number of significant
figures and the correct units!
1. What temperature would be required to change the volume of a gas from 5.4L to 7.6L if
its original temperature was 560K?
2. A 1.50 L of CO2 in a bottle of soda at 10.0°C is left on the counter and warms up to
37.0°C. What is the new volume of CO2?
3. When 250. mL of O2 is heated, there is now 310. mL O2 at 273K. What is the original
temperature in oC?
9
4. Your Valentine’s Day balloon has a maximum volume of 5.5L. Your balloon originally has a
volume of 5.2L at 288K. When you walk into Mrs. Dowell’s classroom, you realize that they
have finally fixed the heat. The temperature of her classroom is now 320K. Should you
worry that your balloon will pop? Support your answer with calculations!
5. A Pepsi can was easily crushed after being placed in an ice bath. If initially the can
contained 250mL of gas at 380K, what would the new volume of the gas be if the
temperature decreased to 280K when it was placed in the ice bath?
10
Gay-Lussac’s Law
Magnet Summary
State G-L’s Law.
General Graph for G-L’s Law
Equation for G-L’s Law
Gay-Lussac’s Law
Temperature must be in
Direct or Inverse?
.
EXAMPLE PROBLEM
A certain gas has a pressure of 56.0kPa at a temperature of 56.1oC. If the volume
remains constant, what would be the new pressure if the temperature was
increased to 78.2oC?
11
Practice Problems for Gay-Lussac’s Law
Be sure to show all work. For every problem, report your answer with the correct number of significant
figures and the correct units!
1. A gas has a pressure of 6.58 kPa at 539K. What is the pressure at 211K if the volume
remains constant?
2. A gas in an aerosol can is at a pressure of 103kPa at 25.0°C. If this can is throw into a
fire, the pressure increases to 2250kPa. What is the temperature inside the fire?
12
Combined Gas Law
Charles's Law
Boyle's Law
Gay-Lussac's Law
Combined Gas
Law
Temperature must be in
.
Remember: STP = ____ atm and ___ K or ___°C
Example Problems
1. A hot air balloon has a volume of 7500L at 270K and a pressure of 1.2atm. What will be
the volume of the balloon if the pressure changed to 0.90atm and the temperature
decreases to 230K?
2. The volume of a gas at STP is 22.4L. At 12.0oC, the volume of the balloon changes to
55.0L. What is the new pressure?
13
Practice Problems for Combined Gas Law
3. A 5.00 L air sample at 170 K has a pressure of 107 kPa. What is the new pressure if the
temperature is raised to 548 K and the volume expands to 7.00L?
4. A gas at 880mmHg and 298K occupies a container with an initial volume of 1.00 L. The
pressure increases to 1980mmHg as the temperature rises to 398K. What will be the
new volume?
5. The volume in a gas filled balloon is 30.0 L at 40.0°C and 3.6 atm of pressure. What
volume will the balloon occupy at STP?
14
Mixed Practice Problems
Be sure to show all work. For every problem, report your answer with the correct number of significant
figures and the correct units!
1. You have 17 L of F2(g) at a pressure of 2.3 atm and a temperature of 299K. If you raise
the temperature to 350K and lower the pressure to 1.5 atm, what is the new volume of
your F2(g)?
2. Hydrogen gas was cooled from 150°C to 50.°C. The new volume of the gas is 75 mL.
What was the original volume of the gas?
15
3. You breathe in 10.0mL of oxygen gas at 298K. When it enters your lungs, the
temperature is raised so that the oxygen gas has a new volume of 11.2mL. What is the
temperature inside your lungs in degrees Celsius?
4. The pressure of a 175mL sample of neon gas was raised causing the volume to change to
125mL. If the original pressure is 85.0kPa, what is the new pressure of the gas?
5. The pressure of air inside of your tire is 5.3atm at 0°C. What would the new pressure
inside of your tire be if you leave it on the counter and its temperature increases to
25°C?
16
Gas Properties Simulation
1. What happens to the particles as you increase the temperature?
2. What happens to the particles speed as you decrease the size of the particles?
3. Add at least ten gas particles, closely observe all the particles. Do they move at the same
speed?
4. How does pressure change with temperature? Explain why in terms of the frequency of
gas particles collisions with the container.
5. How does pressure change with the number of particles present? Explain why in terms of
the frequency of gas particles collisions with the container.
6. If you increase the volume of a container, what happens to pressure? Explain in terms of
the collision of gas particles with the walls of the container.
17
Dalton’s Law of Partial Pressures
Statement of Dalton’s Law
Picture of Dalton’s Law
Dalton’s Law of
Partial Pressures
Formula for Dalton’s Law
Important Reminder for Dalton’s Law
Formula for Dalton’s Law
A partial pressure is the pressure a gas would have or would exert if it
were
in the container.
Example Problems
1. Air contains oxygen, nitrogen, carbon dioxide, and trace amounts of other gases. What is
the partial pressure of oxygen (Poxygen) at 101.3kPa if the partial pressures of nitrogen,
carbon dioxide, and other gases are 79.1kPa, 0.0400kPa, and 0.940kPa, respectively.
2. A mixture of gases contains oxygen, nitrogen, and helium. The partial pressure of oxygen
is 2.1atm. The partial pressure of nitrogen in 0.21atm, and the partial pressure of helium
is 7.8atm. Determine the total pressure of this mixture.
18
Practice Problems for Dalton’s Law
1. At high altitudes, pilots have to supplement their supply of oxygen. In this
mixture, there are oxygen and nitrogen gases. If nitrogen’s partial pressure
is 250mmHg, calculate the partial pressure of oxygen if the total pressure is
710mmHg.
2. Saturn’s atmosphere is composed of hydrogen and helium. If the partial
pressures of the gases are 25.0atm and 1.20atm, respectively, what is the
total pressure?
Ideal Gas Law
Describing the Behavior of Ideal Gases
PV=nRT
P=
Values for R
0.08206
V=
8.314
n=
R=
62.4
T=
*Works best at
temperatures and
*MUST BE IN _____________!!
*List the diatomics:
L atm
mol K
L kPa
mol K
L mmHg
mol K
pressures!
19
Example Problems
1. A 5.60 L sample of an ideal gas contains 0.954 moles at 742 mmHg. Calculate
the temperature.
2. What volume is occupied by 19.6g of methane, CH4, at 27.0oC and 1.59atm?
3. What mass of 2250mL chlorine gas at 45.0oC and 120.kPa?
20
More Challenging Problems
4. Nitrogen and hydrogen gases react to produce ammonia. Determine the mass
of ammonia that would be produce if you reacted 4.00L at 298K and 1.50
atm.
5. Water decomposes to form oxygen and hydrogen. If 3.4g of water
decomposes, what volume of hydrogen gas would be formed at 56oC and 2.3
atm?
21
Practice Problems on the Ideal Gas Law
1. Determine the volume occupied by 0.582mol of oxygen gas at 285K and
98.2kPa.
2. What is the temperature of an 85.0g sample of carbon dioxide gas if its
volume is 2.00L and it has a pressure of 2.50atm?
3. What is the mass of 5.0L of oxygen gas at 55oC with a pressure of
850mmHg?
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4. The following reaction occurs at 250K and 0.80 atm.
H2 + Cl2  2 HCl
If 56g of HCl is formed, calculate the volume of hydrogen that is reacted.
5. A typical lighter requires the combustion of butane, C4H10. Determine the
mass of butane that would be combusted to form 450.mL of carbon dioxide
gas at 333K and 1.02 atm.
23