Gas Laws Lesson 2 PPT For Student

1.
Intro to Boyle’s Law

 Imagine that you hold the tip of a
syringe on the tip of your finger so no
gas can escape. Now push down on
the plunger of the syringe.
What happens to the volume in the

syringe?
What happens to the pressure the gas is

exerting in the syringe?
1. Boyle’s Law
1. Boyle’s Law
 The pressure and volume of a gas are
inversely proportional (as one
increases, the other decreases, and
vice versa
• at constant mass & temp
V
1. Boyle’s Law
Boyle’s Law leads to the mathematical

expression: *Assuming temp is constant
P1V1=P2V2
Where P1 represents the initial pressure V1
represents the initial volume,
And P2 represents the final pressure V2
represents the final volume

Example Problem:
A weather balloon with a volume of 2000L at
a pressure of 96.3 kPa rises to an altitude of
1000m, where the atmospheric pressure is
measured to be 60.8kPa. Assuming there
is no change in the temperature or the
amount of gas, calculate the weather
balloon’s final volume.
Example Problem:
2. Charles’ Law
The volume and absolute

temperature (K) of a gas are
directly proportional (an
increase in temp leads to an
increase in volume)
• at constant mass &
pressure
V
T
2. Charles’ Law
2. Charles’ Law
 Charles’ Law leads to the

mathematical expression:
*Assuming pressure remains

constant
Example Problem:
A birthday balloon is filled to a volume of
1.5L of helium gas in an air-conditioned
room at 293K. The balloon is taken
outdoors on a warm day where the volume
expands to 1.55L. Assuming the pressure
and the amount of gas remain constant, what
is the air temperature outside in Celsius?
Example Problem:
3. Intro to Gay-Lussac’s Law
 Imagine you have a balloon inside
a container that ensures it has a
fixed volume. You heat the
balloon.
What is happening to the temp of

the gas inside the balloon?
What will happen to the pressure

the gas is exerting on the balloon?
3. Gay-Lussac’s Law
The pressure and absolute

temperature (K) of a gas are
directly proportional (as
temperature rises, so does
pressure)
• at constant mass &
volume
P
T
2. Gay-Lussac’s Law
 Gay-Lussac’s Law leads to the

mathematical expression:
*Assuming volume remains constant

Example Problem:
The pressure of the oxygen gas inside a

canister with a fixed volume is 5.0atm at
15oC. What is the pressure of the oxygen
gas inside the canister if the temperature
changes to 263K? Assume the amount of
gas remains constant.
Example Problem:
4. Combined Gas Law
By combining Boyle’s, Charles’ and Gay
Lussac’s Laws, the following equation is
derived:
P1V1 P2V2
=
T1 T2
Example Problem:
A gas occupies 7.84 cm3 at 71.8
kPa & 25°C.Find its volume at STP
or Standard Temperature and
Pressure (273.15 Kelvin and a
pressure of 1 atm)
So, while it's common to use liters for gas
volume in many gas law problems, it's not
strictly necessary. As long as you use
consistent units throughout the calculation,
the units will cancel out during the solution.
In the provided solution, the volume was

given in cubic centimeters (cm3), and we
used that directly in the calculation. We
didn't need to convert it to liters because
the units cancel out anyway, resulting in the
correct volume in the desired units (cubic
centimeters in this case).
Avogadro’s Law states that equal
volumes of gases at the same
temperature and pressure contain equal
number of molecules.
A mole (mol) is a unit of measurement

that represents the amount of a
substance that contains 6.022 x 10^23
entities, such as atoms, ions, particles, or
molecules. This number is also known as
Avogadro's number, named after the
Italian scientist Amedeo Avogadro.
• 1 mole is equal to 6.022 x particles of gas.
• 6.022 x 10^23 particles of gas occupy a
volume 22.4 L
Example Problem:
A 2.7 mole of gas has a volume of 2.9 L at certain
temperature and pressure. Find the new volume (in
mL) of this gas if 5 moles are added to the original
volume under the same conditions.
Example Problem:
R=0.0821
Latm/molK
or
R=8.315
dm3kPa/molK
Example Problem:
A sample of helium occupies 10 L of space
at STP. How many moles of helium are
present in the sample?
Standard Temperature and Pressure:

1atm and 273.15 K
Example Problem:
Example Problem:
A party balloon is filled with a mixture of
helium and oxygen at a total pressure of 1.0
atm. The mole fraction of helium (He) is 0.7.
If the balloon is accidentally popped, what
will be the partial pressure of each gas in
the surrounding air?
Example Problem:
Another Example Problem:
A gas cylinder contains a mixture of

hydrogen, helium, and neon gases with
partial pressures of 300 mmHg, 400 mmHg,
and 500 mmHg, respectively. Calculate the
total pressure exerted by the mixture at
constant temperature.
300 mmHg + 400 mmHg + 500 mmHg = 1200

mmHg
Molar mass is the mass of one mole of a
chemical compound, or the number of
grams per mole (g/mol) of that compound.
Heavier and slower gas molecules find the

exit less often – this means that it has slower
effusion.
Lighter and faster gas molecules find the exit

more often – this means that it has faster
effusion.
Example Problem:
Which gas has a higher rate of
effusion? Oxygen gas (O2) or
Argon (Ar)
(Base the Molar mass in the previous
slide)
Example Problem:
1. Which gas law describes the relationship
between Volume and a Mole
2. What is the formula of Ideal
Gas?
3. What is the Dalton’s law of partial
pressure?
4. What does the Graham’s law tell
us?
Real life Examples/Situation of Gas Laws
Boyle’s Law:
Scuba Diving: Deeper dives mean higher pressure,
compressing air in the scuba tank per Boyle's Law.
Soda Can: Shaking a sealed soda can increases
pressure, reducing the volume of dissolved gas (CO2),
leading to the hiss when opened.
Car Tires: Inflating tires increases pressure,
compressing the air inside and reducing its volume,
ensuring tire firmness for driving.
Lungs: Inhalation expands lung volume, lowering lung
pressure and drawing air into the lungs to balance with
atmospheric pressure.
Balloons: Squeezing a balloon decreases its volume,
raising internal pressure, potentially causing bursting
due to Boyle's Law.
Charle’s Law:
Hot Air Balloons: Heating air in a hot air balloon
increases its volume per Charles's Law, making the
balloon less dense and allowing it to ascend.
Weather Balloons: Rising into lower pressure zones
causes weather balloons to expand due to Charles's
Law, aiding atmospheric data collection.
Tire Pressure: Driving heats car tires, expanding the air
inside according to Charles's Law, resulting in
increased tire pressure.
Balloons in the Sun: Sunlight warms balloons, causing
air inside to expand per Charles's Law, leading to
balloon inflation.
Cooking: Heat causes air in food to expand, making it
rise and become fluffy, as demonstrated by rising
baked goods, in line with Charles's Law.
Gay-Lussac’s Law:
Pressure Cooker: Heating a pressure cooker increases
internal pressure, accelerating cooking due to
heightened temperature and pressure, following Gay-
Lussac’s Law.
Aerosol Cans: Warming aerosol cans elevates internal
pressure, intensifying spray force upon nozzle
depression, in accordance with Gay-Lussac’s Law.
Internal Combustion Engines: Combustion heats
engine chambers, boosting pressure per Gay-Lussac’s
Law, propelling the piston for power generation.
Hot Air Balloon Burners: Heating balloon air raises its
pressure and temperature, enabling ascent in line with
Gay-Lussac’s Law.
Weather Systems: Temperature-induced pressure
changes shape weather phenomena, like high and low-
pressure systems, as dictated by Gay-Lussac’s Law.
Combined Gas Law:
Diving: As a scuba diver descends deeper underwater,
both pressure and temperature increase, affecting the
volume of the air in their scuba tank according to the
combined gas law.
Hot Air Balloons: The combined gas law governs the
behavior of the gas inside a hot air balloon as it
ascends to higher altitudes where both pressure and
temperature decrease.
Car Tires: Changes in temperature and pressure inside
car tires due to driving conditions are described by the
combined gas law.
Weather Balloons: The behavior of the gas inside
weather balloons as they rise through the atmosphere,
experiencing changes in both temperature and
pressure, can be analyzed using the combined gas
law.
Avogadro’s Law:
Baking: Adding more eggs to a baking recipe
increases the amount of gas (e.g., carbon dioxide)
produced during baking, leading to a rise in volume
and fluffiness of the baked goods.
Party Balloons: Inflating more balloons with the same
amount of helium gas leads to an increase in the total
volume of the balloons, illustrating Avogadro's law.
Chemical Reactions: When a fixed amount of gas is
produced in a chemical reaction (e.g., from the
decomposition of hydrogen peroxide), the volume of
the gas increases proportionally to the number of
moles of gas produced.
Gas Storage Tanks: Increasing the amount of gas
stored in a fixed-size tank leads to an increase in
pressure, demonstrating Avogadro's law.
Assignment:
Choose 4 out of 8 gas laws and relate each

in real-life situations. How important is the
gas law in daily life? (Essay: Minimum of 2
sentences each)

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1.

Intro to Boyle’s Law

What happens to the volume in the

What happens to the pressure the gas is

Boyle’s Law leads to the mathematical

represents the initial volume,

And P2 represents the final pressure V2

represents the final volume

The volume and absolute

 Charles’ Law leads to the

*Assuming pressure remains

What is happening to the temp of

What will happen to the pressure

The pressure and absolute

 Gay-Lussac’s Law leads to the

*Assuming volume remains constant

The pressure of the oxygen gas inside a

In the provided solution, the volume was

A mole (mol) is a unit of measurement

Standard Temperature and Pressure:

A gas cylinder contains a mixture of

300 mmHg + 400 mmHg + 500 mmHg = 1200

Heavier and slower gas molecules find the

Lighter and faster gas molecules find the exit

Choose 4 out of 8 gas laws and relate each

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