CP Chemistry
Mrs. Klingaman
Chapter 11: Gases
Name: _________________________
Mods: ____________
Chapter 11: Gases
Reading Guide
11.1 – Gases & Pressure (pgs. 341-348)
1. How do gas molecules generate pressure?
2.
Define pressure –
3. The pressure exerted by a gas depends on __________________, ______________________,
and the number of ____________________ present.
4. The atmosphere surrounding earth contains about _______% nitrogen, _______% oxygen, and
_______% other gases, including argon and carbon dioxide. These atmospheric gases all exert
a pressure – known as atmospheric pressure – on every surface they come in contact with.
5. A barometer is a type of device used to measure
atmospheric pressure. Using figure 1.3 (at right) describe
how a mercury barometer works.
6. Units of Pressure:
a. ____________________________________ (mm Hg) = torr
b. ___________________________________________ (atm)
c. _________________________ (Pa) and _____________________________ (kPa)
d. ____ atm = ________ mm Hg = ________ torr = _________________ Pa = _________kPa
7. Standard Temperature & Pressure (STP) – for purposes of comparison, scientists have
agreed upon standard conditions of ______ atm pressure and _______°C = ________K.
11.2 – The Gas Laws (pgs. 349-357)
11. Boyle’s Law:
a. Gas volume and pressure are ________________________ proportional.
b. This means that as the pressure of a gas increases (at constant temperature), the volume
of the gas ____________________.
c. Write the equation which expresses Boyle’s Law below:
(P1 and V1 represent initial conditions and P2 and V2 represent a different set of conditions)
d. Graphing Boyle’s Law:
Use figure 2.2 to replicate a volume vs.
pressure graph for a gas at constant
temperature. Be sure to label the x and y
axis appropriately.
12. Charles’s Law:
a. Gas volume and temperature are _________________________ related.
b. This means that, when the temperature increases the volume of a fixed number of gas
molecules must ________________________ if pressure is to stay the same.
c. Temperature values used in calculations throughout this chapter must be in Kelvins!!!
What is the relationship between the Celsius and Kelvin scale?
d. Write the equation which expresses Charles’s Law below:
(V1 and T1 represent initial conditions and V2 and T2 represent a different set of conditions)
e. Graphing Charles’s Law:
Use figure 2.4 to replicate a volume vs.
temperature graph for a gas at constant
pressure. Be sure to label the x and y
axis appropriately.
13. Gay-Lussac’s Law:
a. Gas pressure and temperature are _________________________ related.
b. This means that, when the temperature increases the pressure of a fixed number of gas
molecules must ________________________ if volume is to stay the same.
c. Again, temperature values used in calculations must be in Kelvins!!!
d. Write the equation which expresses Gay-Lussac’s Law below:
(P1 and T1 represent initial conditions and P2 and T2 represent a different set of conditions)
e. Graphing Gay-Lussac’s’s Law:
Use figure 2.6 to replicate a pressure vs.
temperature graph for a gas at constant
volume. Be sure to label the x and y
axis appropriately.
14. Combined Gas Law:
a. This gas law expresses the relationship between _______________________,
________________________, and _____________________________ when there is a
fixed amount of gas.
b. Again, temperature values used in calculations must be in Kelvins!!!
c. Write the equation which expresses the Combined Gas Law below:
(P1, T1 , V1 represent initial conditions and P2, T2 , V2 represent a different set of conditions)
11.3 – Gas Volumes & the Ideal Gas Law (pgs. 358-365)
15. Define Avogadro’s Law –
16. The volume occupied by one mole of a gas at STP is known as the standard molar volume
of a gas. It has been found to be _______________ L.
a. You can use this molar volume relationship to find the number of moles, and therefore the
mass, of a given volume of of any gas at STP conditions.
17. Ideal Gas Law:
a. Define the ideal gas law -
b. Write the equation which expresses the ideal gas law:
(P = pressure; V = volume; T = temperature; n = # of moles of gas; R = ideal gas constant)
c. On pg. 364 (last paragraph) give the numerical value of the ideal gas constant, R including
the units:
R=
d. When solving any ideal gas law problem you must first check the units of the variables
given in the problem. If necessary, you must convert volume to _________________,
pressure to _____________________, temperature to ________________ and masses to
____________________ before using the ideal gas law
11.4 – Diffusion & Effusion (pgs. 366-369)
Skip this section
Gases: Notes & Introduction
1. What are the four variables needed to define the physical condition, or state, of a gas?
2. Pressure: the amount of ____________________ applied to an area; gasses exert pressure on
any surface they come in contact with
3. _________________________ pressure is the weight (a force due to gravity) of air per unit of
area.
4. Units of Pressure & Unit Conversions:
Pascal (Pa) = SI base, kilopascal (kPa), millimeters of mercury (mm Hg or torr), & atmosphere
(atm)
Standard Atmospheric Pressure:
1 atm = 760 mm Hg = 760 torr = 1.01325 x 105 Pa = 101.325 kPa
a. 0.357 atm = ________________________ torr
b. 6.6 x 10-2 mmHg = ________________________ atm
c. 177.2 kPa = ________________________ torr
5. Standard Temperature and Pressure Conditions (STP) :
Temperature = ____________ or ____________
Pressure = _________________
Boyle’s Law WS #1
Formula:
Variables Defined in Equation:
Real-life application:
Relationship:
1. If I have 5.6 liters of gas in a piston at a pressure of 1.5 atm and compress the gas until its
volume is 4.8 L, what will the new pressure inside the piston be?
2. I have added 15 L of air to a balloon at sea level (1.0 atm). If I take the balloon with me to
Denver, where the air pressure is 0.85 atm, what will the new volume of the balloon be?
3. I’ve got a car with an internal volume of 12,000 L. If I drive my car into the river and it
implodes, what will be the volume of the gas when the pressure goes from 1.0 atm to 1.4 atm?
4. The highest pressure ever produced in a laboratory setting was about 2.0 x 106 atm. If we
have a 1.0 x 10-5 L sample of a gas at that pressure, and then release the pressure until it is
equal to 0.275 atm, what would the new volume of that gas be?
5. Part of the reason that conventional explosives cause so much damage is that their detonation
produces a strong shock wave that can knock things down. While using explosives to knock
down a building, the shock wave can be so strong that 12 L of gas will reach a pressure of
3.8 x 104 mmHg. When the shock wave passes and the gas returns to a pressure of 760
mmHg, what will the volume of that gas be?
Boyle’s Law WS #2
6. 1.00 L of a gas at standard pressure (1.00 atm) is compressed to 473 mL. What is the new
pressure of the gas?
7. Synthetic diamonds can be manufactured at incredibly high pressures. If we took 2.00 L of
gas at 1.00 atm and compressed it to a pressure of 6.00 x 104 atm (the pressure needed to
create a diamond), what would the volume of that gas be?
8. Atmospheric pressure on the peak of Mt. Everest is much lower than what our bodies are
normally accustomed to, which is why climbers need to bring oxygen tanks for the last part of
the climb. If the climbers carry 10.0 L tanks with an internal gas pressure of 3.04 x 104 mmHg,
what will be the volume of the gas when it is released from the tanks into an atmospheric
pressure of only 150 mmHg?
9. Submarines need to be incredibly strong to withstand the extremely high pressure of water
pushing down on them. An experimental research submarine with a volume of 15,000 L has
an internal pressure of 1.2 atm. If the pressure of the ocean breaks the submarine, forming a
bubble with a pressure of 250 atm pushing on it, what will the volume of that bubble be?
10. Divers get “the bends” if they come up too fast because gas in their blood expands, forming
bubbles in their blood. If a diver has 0.05 L of gas in his blood under a pressure of 250 atm,
then rises instantaneously to a depth where his blood has a pressure of 50.0 atm, what will the
volume of gas in his blood be? Do you think this will harm the diver?
Charles’s Law WS #1
Formula:
Variables Defined in Equation:
Real-life application:
Relationship:
1. If I have 45 liters of helium in a balloon at 250C and increase the temperature of the balloon to
550C, what will the new volume of the balloon be?
2. Calcium carbonate decomposes at 12000C to form carbon dioxide and calcium oxide. If 25
liters of carbon dioxide are collected at 12000C, what will the volume of this gas be after it
cools to 250C?
3. I have 130 liters of gas in a piston at a temperature of 2500C. If I cool the gas until the volume
decreases to 85 liters, what will temperature of the gas be?
4. On hot days, you may have noticed that potato chip bags seem to “inflate”, even though they
have not been opened. If I have a 250 mL bag at a temperature of 190C, and I leave it in my
car which has a temperature of 600C, what will the new volume of the bag be?
5. I have a thermometer which measures temperature by the compressing and expanding of gas
in a piston. I have measured that at 1000C, the volume of the piston is 20 L. What is the
temperature outside if the piston has a volume of 15 L?
Charles’s Law WS #2
6. I place a balloon inside of my refrigerator. If the balloon initially has a temperature of 220C
and a volume of 0.5 L, what will the new volume of the balloon be when it cools to a
temperature of 40C?
7. A man heats a balloon in the oven. If the balloon initially has a volume of 0.4 L and a
temperature of 200C, what will the volume of the balloon be after he heats it to a temperature
of 2500C?
8. A soda bottle is flexible enough that the volume of the bottle can change even without opening
it. If you have an empty soda bottle (volume of 2 L) at room temperature (250C), what will the
new volume be if you put it in your freezer (-40C)?
9. Some students believe that teachers are full of hot air. If I inhale 2.2 L of gas at a temperature
of 180C and it heats to a temperature of 380C in my lungs, what is the new volume of the gas?
10. How hot will a 2.3 L balloon have to get to expand to a volume of 400 L? Assume that the
initial temperature of the balloon is 250C.
Gay-Lussac’s Law WS #1
Formula:
Variables Defined in Equation:
Real-life application:
Relationship:
1. A gas with a pressure of 5.4 atm and at 250C is raised to a new temperature of 780C. What is
the new pressure?
2. A gas with a pressure of 550 torr and at 1100C is raised to atmospheric pressure (760 torr).
What is the new temperature?
3. A gas with a pressure of 7.5 atm and at 300C is raised to a new temperature of 1500C. What
is the new pressure?
4. A gas with a pressure of 780 torr and at 550C is lowered to a new pressure of 640 torr. What
is the new temperature?
5. A gas with a pressure of 5.6 atm and at 1500C is lowered to a new temperature of 200C. What
is the new pressure?
Formula:
Combined Gas Law WS #1
1. The pressure of a gas changes from 120 kPa to 50 kPa. The volume changes from 45 L to 40
L. If the initial temperature is 81oC, what is the final temperature?
2. A sample of nitrogen goes from 21 m3 to 14 m3 and its pressure increases from 100 kPa to
150 kPa. The final temperature is 300 K. What was the initial temperature?
3. A sample of argon goes from 500 K to 350 K and its pressure changes from 280 kPa to 380
kPa. If the initial volume is 18 dm3, what is the final volume?
4. A sample of neon experiences a pressure drop from 75 kPa to 53 kPa. The temperature
increases from 27oC to 93oC. If the initial volume is 12 L, what is the final volume?
5. The temperature of a gas increases from 212oC to 380oC. The volume goes from 30 dm3 to
18 dm3. If the final pressure is 1.85 atm, what was the initial pressure?
Combined Gas Law WS #2
6. A child has a toy balloon with a volume 1.80 L. At the time the balloon was filled, the
temperature was 20oC and the pressure was 1.0 atm. If the child were to let go of the balloon
and it rose 3 km into the sky where the pressure is 0.667 atm and the temperature is 10oC,
what would the new volume of the balloon be?
7. If I initially have a gas at a pressure of 12 atm, a volume of 23 L, and a temperature of 200K,
and then I raise the pressure to 14 atm and increase the temperature to 300K, what is the new
volume of the gas?
8. A gas that has a volume of 28 L, a temperature of 45oC, and an unknown pressure has its
volume increased to 34 L and its temperature decreased to 35oC. If I measure the pressure
after the change to be 2.0 atm, what was the original pressure of the gas?
9. I have an unknown volume of gas at a pressure of 0.5 atm and a temperature of 325K. If I
raise the pressure to 1.2 atm, decrease the temperature to 320K, and measure the final
volume to be 48 L, what was the initial volume of the gas?
10. If I have 2.9 L of gas at a pressure of 5 atm and a temperature of 50oC, what will be the
temperature of the gas if I decrease the volume of the gas to 2.4 L and decrease the pressure
to 3 atm?
Formula:
Ideal Gas Law Practice WS #1
R=
1.
How many moles of gas does it take to occupy 120 L at a pressure of 2.3 atmospheres and a
temperature of 340 K?
2.
If I have a 50 L container that holds 45 moles of gas at a temperature of 2000C. What is the
pressure inside the container in atmospheres?
3.
It is not safe to put aerosol canisters in a campfire, because the pressure inside the canisters
gets very high, and they can explode. If I accidentally throw a 1.0 L canister that holds 2
moles of gas into fire that is 14000C, what is the pressure inside the canister in atmospheres?
4.
How many moles of gas are in a 30 L scuba canister if the temperature of the canister is 300 K
and the pressure is 200 atmospheres?
5.
I have a balloon that can hold 100 L of air. If I blow up this balloon with 3 moles of oxygen gas
at a pressure of 1 atmosphere, what is the temperature of the balloon in degrees Celsius?
Ideal Gas Law WS #2
6.
If 3.7 moles of propane are at a temperature of 28oC and are under 1.52 atm of pressure, what
volume does the sample occupy?
7.
A sample of carbon monoxide at 57oC and under 0.67 atm of pressure takes up 85.3 L of
space. What mass of carbon monoxide is present in the sample?
(Hint- solve for mol, convert to g)
8.
At –45oC, 71 g of fluorine (F2) gas take up 6843 mL of space. What is the pressure of the
gas? (Hint- convert g mol, then use ideal gas law)
9.
At 1.28 atm, 145 g of carbon dioxide (CO2) have a volume of 34.13 L. What is the temperature
of the sample? (Hint- convert g  mole, then use ideal gas law)
10.
CHALLENGE!! At 137oC and under a pressure of 3.11 atm, a 276 g sample of an unknown
noble gas occupies 13.46 L of space. What is the gas? (Hint: remember the units for molar
mass are g/mol)
Combined Gas Law:
Ideal gas Law:
Mixed Gas Law WS
R=
1. A gas takes up 16 L of space, has a pressure of 2.5 atm, and a temperature of 300 K. If I
raise the temperature to 350 K and lower the pressure to 1.2 atm, what is the new volume of
the gas?
2. A gas exerts 1.2 atm of pressure. If the temperature is raised from 25oC to 100oC, find the
new pressure.
3. The pressure of some N2 drops from 315 kPa to 220 kPa. If the initial volume is 1.4 L, find the
new volume.
4. If I have an unknown quantity of gas at a pressure of 0.7 atm, a volume of 24 L, and a
temperature of 205 K, how many moles of gas do I have?
5. When the temperature of a gas changes, its volume decreases from 12 cm3 to 7 cm3. If the
final temperature is measured to be 18oC, what was the initial temperature?